Thread: Square D panel

Could someone comment on this SQ D panel? There are 6 breakers to disconnect the panel. Not sure how to calculate the amperage. One breaker is 50 amps and the others are less. Main entrance would support 100 amp.

That appears to be a split buss. Look for the rating on the label visible on the left inside the panel. Then go with the smallest of the rating, first disconnect (if there is one ahead of this) or the capacity of the entrance conductors. My guess would be 150 amp rating but downgrade that to the conductors so I would go with the 100 you mentioned.

It appears to be a split bus panel with the 50 amp breaker protecting the lower half. But this reply will bump your thread ahead of that other one which has bored most of us for 3 weeks, so hopefully you will get your answer today.

Thanks for the quick response.

That is a (many decades old) Split Bus Load Center.This panel was issued with a HOST of limitations included in its labeling (left side of panel) and includes a diagram, stab ratings limitations, limitations when used as service equipment, etc.The panel has been filled and used subsequent to its original installation, in CONFLICT with those originally listed and labeled limitations (including references to long-ago and differently configured NEC references which won't match up with 2002 & forward references AT ALL.That upper left 2P common trip 50A breaker is feeding the sub bus structure below (conductors up and over and down behind where it taps in to the sub bus behind the installed breakers.Next "set" below left and right are each a pair of single pole breakers which are not tied of unknown amperage but are most certainly equal to OR LESS THAN 30 amps each and are not allowed to be in those spaces as single pole untied breakers equal to or less than 30 amps.I suspect (panel diagram & label would confirm) that this particular panel upper bus was confined to the top four 2-P breaker positions; however some (and the majority of those less-old than this panel) would be the top six 2-pole positions, for the upper bus, and the lower bus would be fed off of a single 2-pole from above - but not always...sometimes there might be two sub-busses, each fed from a separate 2-P above (however I do not recall a single square-D branded load center which incorporated two sets of sub-busses for a res load center).You need to share the photo you of course remembered to snap of the panel labeling limitations, identification & diagram which was all contained on the inside left wall of the panel to VERIFY the beginning of the sub buss, and review the limitations when employed as service equipment and when the sub-bus is utilized - AND the (and it will be) STAB RATING limitations regarding the use of tandems and where (limited as to location) they MAY be installed.The rest of the spaces below are "fed" by the 50 amp circuit breaker at the upper left.The tandem breakers (four) which have all been installed all at the lower right are likely limited to just the last (bottom) two spaces left and right, IF they were permitted at all .As this has not been your first post about older split bus panels, you should know by know to take pictures and notes of the labeling restrictions, panel identification and the diagram. That label contqains ALL the information required along with the pictures you did share.The old rules regarding number of terminals on the neutral/grounds bus and a better shot of same would also help to narrow down the limits when/if a portion of the panel label is defaced, unreadable, or missing.You will need to ADD up the 2P values of the two, four, or six maximum 2P or tied single pole breakers on the upper buss leaves (fed directly by the mains) to determine the service's rated protection. However, single pole breakers (untied) and with values equal to or less than 30 Amps have been installed in the upper bus and it as you noted is not protected by a single main breaker or a maximum of two mains breakers, and therefore would violate the original listing as it (the upper buss structure) would be functioning as a Lighting and Appliance panel board which must be protected by a maximum of two circuit breakers or two (one for each pole) fuses. (rules which were in older editions of the NEC and therefore incorporated into the limitations of the UL listing and classification esp. when calculated protections for AIC and SSCR were employed (prior to required testing mid 80s which led to the elimination of split panel load centers being offered a few years later - that's the K.I.S.S. version).

Charles Buell is a Washington home inspector and author. He created this picture of a similar Square D split bus panel, although the breaker feeding the lower section in his pic is on the right side rather than the left.

HG is correct in that the upper section was intended for the 240 volt circuits and all the 120 volt lighting circuits were expected to be supplied by the lower section only. The lower section is fed by one breaker in the upper section. So your shorter panel probably has 50 amps available for lighting and general, and space available for 3 double breakers in the upper section.

We don't have enough info to say for sure what the size of the service would be. 100 amps is a reasonable estimate.

Originally Posted by John Kogel

Charles Buell is a Washington home inspector and author. He created this picture of a similar Square D split bus panel, although the breaker feeding the lower section in his pic is on the right side rather than the left.

HG is correct in that the upper section was intended for the 240 volt circuits and all the 120 volt lighting circuits were expected to be supplied by the lower section only. The lower section is fed by one breaker in the upper section. So your panel has 50 amps available for lighting and general, and space available for 5 double breakers in the upper section.

We don't have enough info to say for sure what the size of the service would be. 100 amps is a reasonable estimate.

NOT ALL split bus panels have SIX double-pole positions in the Mains Bus!

I am quite certain that the OP's panel does NOT have a six-position 2-pole circult breaker length mains bus configuration. It likely has only two (Main & 'range' config) or more likely FOUR 2-pole positions on the mains bus (I believe this one is four, but the panel diagram would confirm where the "Main Lighting" bus begins (tap fed from the 50 amp breaker).

Please note the OP's panel is shorter overall, and has fewer neutral/g terminals. Square D made 2 & 4 split bus load centers in addition to the later more popular (late 70s & early 80s) six-position mains (max) split bus load centers.

You add up the installed mains bus 2-pole breaker positions that is the protected capacity - compare with the rated capacity of the panel labeling for employment as service equipment with sub main employed as L&ABP and compare with capacity of the service conductors.

I have to be honest with you, I knew it was a split bus, and thought to be ok from my past experience, though limited, but posted the picture to make sure, ,,,did not take a picture of the label, but will be going back to pickup the radon and get the pic. Please stand by.

Originally Posted by Russell Melville

Could someone comment on this SQ D panel? There are 6 breakers to disconnect the panel. Not sure how to calculate the amperage. One breaker is 50 amps and the others are less. Main entrance would support 100 amp.

Assuming the installer labeled the panel correctly and from a blurry enlargement of the first photo, I'm guessing it is a split buss with four two-pole main disconnects. A better photo of the label would be interesting. Also, if you get the serial number from the label you can tell the age (probably 50s-60's).

Picture as promised

Originally Posted by Robert Meier

Label says "Suitable for use as service equipment when not more than six main disconnecting means are provided".

Meaningless selective, and NOT RELEVANT to the OP's SUBJECT PANEL'S EMPLOYMENT, ARRANGEMENT, AND USE! Only 1,2 and 3,4 are service disconnects as configured with split bus for 3-wire 120/240 single phase. 1,2 and 3,4 MUST be 240V 2-pole breakers or 120/240 2-pole breakers with common trip or TIED if 120/240 2-pole breakers with individual trip, to be used as service disconnects.

Your selective, OUT-OF-CONTEXT partial quote IS NOT ALL IT SAYS, and does NOT MEAN what you IMPLY within this discussion! If you kept reading AND if you bothered to review the part of the FIRST wiring diagram which can be seen in the picture - or bothered to AGE this QO and were familar with the "white book" of the vintage, the standards of the vintage, the NEC of the vintage, and the wiring diagrams and labeling of the vintage for this obsolete legacy QO, you'd realize that 1,2 and 3,4 MAY NOT ever be used as service disconnects when filled with either single pole breakers OR 120/240 2-pole breakers with independant pole trips that are untied AND that 5,6 can not be wired to be service disconnects UNLESS 7,8 and 9,10 remain empty.

You would see WHAT I TOLD the OP and John K, early on in this discussion.

You can use 5 & 6 as service disconnects ONLY if 7-10 are empty, and either: the sub bus is tapped to the mains bus and filled with 240 breaker no neutral (for single phase 2-wire 240) or 2-pole 120/240 common trip or individual trip breakers that are TIED for 120/240 single phase 3-wire (and 7-10 remain empty); OR the sub bus (which starts at 5/6) is not tied but is jump fed as the top with 3-phase 4-wire delta - with specific requirements for the "B" phase.

non-CTL QO of this style convertible load center LONG AGO old (and obsolete) Series.

ONLY 1,2 AND 3,4 ARE THE SERVICE DISCONNECTS when using as a split bus 120/240V ac single phase 3 wire load center employed as service equipment AND THEY MUST BE EITHER 240 2-POLE OR 120/240 2-POLE WITH COMMON TRIP OR TIED if 120/240 2-pole circuit breakers with individual trip

Just can't make out if the fourth position on the serial number is an "F" as in Frank (1955) a "P" as in Pedro (1963) or an "R" as in Robert ('64) or an A as in Apple (1950).

H August zero-eight for 8th day, Letter in 4th position is year.

Because it doesn't have a ecg bus and only 10-12 N terminals and has few terminals on the grounding bus that (and the non-ctl and vintage) clues one to the surmised (mine) limitation that tandems (old style) if employed are limited to the last (9,10) area of the panel which is why I'm going with "P" 1963 or "R" 1964 for approx age of the convertible QO load center but it could be "F". Grounding conductors for convenience outlets and lighting circuits weren't required but were employed prior to the 62 requirement in the NEC.

I'm also betting this pre-dates either RM's exisitance, or at least his education and experience 'in the field'.

Turn the picture counter clockwise to read the serial number (actually the manifest number for the lot) its stamped across the restrictions for the diagrams just above diagram 1.


Yes obsolete. Wasn't rated for present AIC - and ratings were calculated (long ago determined to be incorrect theory and were based on 10A calculations per stab and never were correct for series under load simultaneous with arc or event switching nor inducitive impedeance ) panels nor CBs were NOT TESTED under the conditions now required for listing approvals today.

One of the reasons not a single mfg of the period and prior is held by the same entity today without having been "purged" and divested and re-organized held by another entity before being sold-off/ re-acquired

Originally Posted by H.G. Watson, Sr.

Meaningless selective, and NOT RELEVANT to the OP's SUBJECT PANEL'S EMPLOYMENT, ARRANGEMENT, AND USE! Only 1,2 and 3,4 are service disconnects as configured with split bus for 3-wire 120/240 single phase. 1,2 and 3,4 MUST be 240V 2-pole breakers or 120/240 2-pole breakers with common trip or TIED if 120/240 2-pole breakers with individual trip, to be used as service disconnects.

Your selective, OUT-OF-CONTEXT partial quote IS NOT ALL IT SAYS, and does NOT MEAN what you IMPLY within this discussion! If you kept reading AND if you bothered to review the part of the FIRST wiring diagram which can be seen in the picture - or bothered to AGE this QO and were familar with the "white book" of the vintage, the standards of the vintage, the NEC of the vintage, and the wiring diagrams and labeling of the vintage for this obsolete legacy QO, you'd realize that 1,2 and 3,4 MAY NOT ever be used as service disconnects when filled with either single pole breakers OR 120/240 2-pole breakers with independant pole trips that are untied AND that 5,6 can not be wired to be service disconnects UNLESS 7,8 and 9,10 remain empty.

You would see WHAT I TOLD the OP and John K, early on in this discussion.

You can use 5 & 6 as service disconnects ONLY if 7-10 are empty, and either: the sub bus is tapped to the mains bus and filled with 240 breaker no neutral (for single phase 2-wire 240) or 2-pole 120/240 common trip or individual trip breakers that are TIED for 120/240 single phase 3-wire (and 7-10 remain empty); OR the sub bus (which starts at 5/6) is not tied but is jump fed as the top with 3-phase 4-wire delta - with specific requirements for the "B" phase.

non-CTL QO of this style convertible load center LONG AGO old (and obsolete) Series.

ONLY 1,2 AND 3,4 ARE THE SERVICE DISCONNECTS when using as a split bus 120/240V ac single phase 3 wire load center employed as service equipment AND THEY MUST BE EITHER 240 2-POLE OR 120/240 2-POLE WITH COMMON TRIP OR TIED if 120/240 2-pole circuit breakers with individual trip

Just can't make out if the fourth position on the serial number is an "F" as in Frank (1955) a "P" as in Pedro (1963) or an "R" as in Robert ('64) or an A as in Apple (1950).

H August zero-eight for 8th day, Letter in 4th position is year.

Because it doesn't have a ecg bus and only 10-12 N/G circuit terminals I'm going with "F" 1955 for age of the convertible QO load center.

I'm also betting this pre-dates either RM's exisitance, or at least his education and experience 'in the field'.

Turn the picture counter clockwise to read the serial number (actually the manifest number for the lot) its stamped across the restrictions for the diagrams just above diagram 1.


Yes obsolete. Wasn't rated for present AIC - and ratings were calculated (long ago determined to be incorrect) NOT TESTED.

One of the reasons not a single mfg of the period and prior is held by the same entity today without having been "purged" and divested and re-organized held by another entity before being re-acquired.

H.G., No disrespect intended, but I think you need a hobby.

Originally Posted by Mark Reinmiller

H.G., No disrespect intended, but I think you need a hobby.

Because I object of R.M.'s "hobby" which is to lead HIs astray?

Only 1,2 and 3,4 are the disconnects, NOT 5,6.

I'm beyond retired. I have several "hobbies".

Robert made a direct quote of the wording from the panel manufacturers lable and get paragraph after paragragh telling he was wrong. Amazing.

HG, if you would stop trying to prove that everyone is wrong, except yourself, you would have noticed that Robert did not say that the panel was being used properly with the single pole and tandems in the top 3 positions on each side. He was simply answering the question about whether the panel could have 4 mains or 6 mains.

As far as attempting to lead HI's astray, do you really think that is Robert's purpose? What a sorry cynical person you must be. His answers are always knowledgeable and also polite. Even when he disagrees you will not see anywhere near the viterol that you spew forth.

Originally Posted by Jim Port

Robert made a direct quote of the wording from the panel manufacturers lable and get paragraph after paragragh telling he was wrong. Amazing.

HG, if you would stop trying to prove that everyone is wrong, except yourself, you would have noticed that Robert did not say that the panel was being used properly with the single pole and tandems in the top 3 positions on each side. He was simply answering the question about whether the panel could have 4 mains or 6 mains.

As far as attempting to lead HI's astray, do you really think that is Robert's purpose? What a sorry cynical person you must be. His answers are always knowledgeable and also polite. Even when he disagrees you will not see anywhere near the viterol that you spew forth.

Again, and K.I.S.S.ing it for you since you require it.

The panel may NOT be employed as service equipment with six disconnects WHEN 120/240 Volts single-phase 3-wire AND ANY use of spaces 7,8,9,10 are filled, wired or not. Single pole breakers and 2-wire 120V single-phase circuits are not allowed on the mains.

Sure you missed that J.K. completely changed his post a full day after I quoted and responded.

I see Jim and Robert are continuing with their insults and bullying tactics with those that disagree with them.

Originally Posted by Robert Meier

First off HG when you use big capital letters in a post (#13) that constitutes yelling at someone. Even if you disagree with a post there is no need to yell. And as for your condescending attitude most of us around here know that your nothing more than on old douche so we're immune to it. As Jim stated I simply posted what was written on the label and made no further comment, if you weren't hyperventilating because you had the chance to slam someone you would have noticed.

(1) (blue): The capital letters weren't "Big" they were the same font! They were simply capital letters. As far as your perceptions as to yelling vs. emphasis, that again is your opinion...Bold and underlining are a relatively "New" aspect. Formatting issues abound for many, constantly and intermittantly for "many" users esp. since the last forum "upgrade". Capital letters are for EMPHASIS, readability and clarity. If you constitute that personally as "YELLING" so be it. Frankly you should be "yelled at". The Mfg (following standards and NEC of the time and in precautionary mode as to readability and emphasis/importance) solely employed the use of CAPITAL LETTERS throughout the labeling portion photographed, even diagrams (drawings); the OP posted numerous photos, yet you either still failed to 'get it' or are intentionally obtuse & malicious to OP (HI in realtime engaged in his livelyhood) and those who participate and/or simply review the discussion.

(2) (red): Ah, dismissive and name calling. Then envoking the royal "we" or assumption of a title so as to have been self-appointed to speak for others, let alone the "majority"...

(3) (black): Ignorant and completely out-of-context, and entirely misleading - be it ignorance or intentionally obtuse and malicious.

Very old style (NEC) vs. transitory style vs. present style. Since has opined on the subject manytimes past (long history M.H.'s NEC forum) - obviously not completely ignorant nor clueless, pattern and activity the instant and other HI forum, therefore MY OPINION regarding implied motivation of 'hobby'. That out-of context and conditional snippet (with scores, literally, of negative limiting exceptions in the applicable references NEC and UL standards) of the time; and the evidenced flow of the instant discussion: was IMO nothing but intentionally and maliciously misleading to the OP and readers of the OT discussion.

Originally Posted by Jim Port

Robert made a direct quote of the wording from the panel manufacturers lable and get paragraph after paragragh telling he was wrong. Amazing.

HG, if you would stop trying to prove that everyone is wrong, except yourself, you would have noticed that Robert did not say that the panel was being used properly with the single pole and tandems in the top 3 positions on each side. He was simply answering the question about whether the panel could have 4 mains or 6 mains.

As far as attempting to lead HI's astray, do you really think that is Robert's purpose? What a sorry cynical person you must be. His answers are always knowledgeable and also polite. Even when he disagrees you will not see anywhere near the viterol that you spew forth.

(1) (black): it was an out-of-context conditional snippet of the label's conditional statements which were conditional on the limitations presented above and were further conditional upon the wiring diagrams below. The panel MAY have one, two, three, four, five, or six main disconnects. The OP's filled panel pictured MAY NOT have six main disconnects, the OP's filled panel pictured "may" only have a maximum of four main disconnects, and none may be individual trip untied 120V poles.

(2) (blue): As usual, you fail to keep track of even a short thread. There are no tandems on the left side nor are there any tandems in the top six breaker positions on the SUBJECT (OP's) vintage convertable QO load center. You seem mightily confused between a borrowed photo off-topic and longer bus panel posted by John Kogel. As usual you are (you're not your) disingenuous in your participation and contributions herein.

(3) (red): Yes, as is your own. Your summarization is untrue; your application of the words "always" and "polite" are as laughable of application and supositions regarding "could" etherial hypothetical (wrong both ways) and your failure at math and comprehension of amperage and voltage vs. power.

Originally Posted by Roland Miller

I see Jim and Robert are continuing with their insults and bullying tactics with those that disagree with them.

Originally Posted by Robert Meier

Thanks Jim, at least we all know that you can read.

Back to the topic, these types of installation are date sensitive given that the code rules have changed over the years. For example in 1981 the NEC added the wording "For existing installations" to Exception #2 of 384.16 which eliminated the new use of split-bus panelboards. Prior to that, the exception provided relief from the not more than two main circuit breakers requirement to protect a lighting and appliance branch circuit panelboard when used in a dwelling as service equipment. I have yet to find where the NEC says that you cannot use 15 or 20 amp CB's as one of the six service disconnects. In fact the 1981 NEC Handbook commentary goes on to say this:



So under 1981 NEC and forward you could use 15 or 20 amp CB's under the exception for existing service equipment in dwellings. Prior to 1981 you could also use them for new installations.

The one caveat would be if the panelboard listing did not allow their use.

Now if anyone would like to discuss this in a gentlemanly fashion I'm extending the olive branch, even you HG.

Wrong.

I'll make this as K.I.S.S. as possible: Not a single pole independant trip on "Service Equipment" that was provided with anything other than STRAIGHT(emphasis) 120V only service (2-wire) (they still exist).

The MULTITUDE (emphasis) of caveats are the multitude of negative exceptions which existed under permissive statements in the old style NEC of the vintage UNDER WHICH the panelboard was originally listed; AND (emphasis) the multitude of limitations expressed in the STANDARD(s) under which the panelboard AND (emphasis) the circuit breakers and or fuses (including series protection within) were Listed; AND the entirety of the limitations issued by the manufacturer(s) of the panelboard and/or the cir breakers which WHEN manufactured (which even classified or legacy breakers mfg or remanufactured today are referenced the original limitations of the panelboard at the time of manufacture).

Therefore, since the listing circa the actual manufactured date of same is always conditional upon the languge of the standard number AND edition listed thereunder, which always references the entirety of the NEC (in this example) edition in effect including the perscribed dates of future (at the timeof the edition) requirements to be later effective ...

Neither the labeling nor the additional (I know trademen today don't think they "gotta read no directions" inserts, data, restrictions OF THE VINTAGE (emphasis),

...nor the entirety of the subsequent restrictions, limitations, etc. which were in place at the time of any subsequent ALTERATION (emphasis) - ADDITION (emphasis), re-work, (that includs replacement of a breaker, especially when not exactly like for like and that includes frame size, total number of stabs, swapping out or moving circuits (one bus br to another - i.e. bus stab ratings restrictions, etc.

...and one of the biggies you always overlook - the AIC limitations (SEE YOUR GREEN (not WHITE) book (emphasis, et. al.).

Your now quite frequently quoted section does not permit today what was NEVER PERMITTED THEN.

120V lighting and 'convenience' branch circuits 10A (not a typo used to be 10 A circuits were allowed - now its 15A minimum)-30A required series protection from the utility (frankly all 10-25 A circuits did - even fused ones).

Hence the old range and a main fused service - and and old uninsulaqted knife switches - the main was the series protection for those 10A to less than 30A circuits - the range (all electric combined cooktop and electric resistance oven) was always greater than 25A. Everything downstream had additional fused protection line side of the branch and a means to safely disconnect even if it were a mere cut-out and/or a switch or cord-cap.


The NEC of the vintage eras I named were NOT configured as it is now, and the "style" (or voice of the writing) was COMPLETEly (emphasis again) DIFFERENT.

wasn't allowed at the time of mfg. wasn't allowed when some putz (or putzes) altered (however many times) the panel post original-installation and employment, and therefore STILL ISN"T ALLOWED NOW.

What you're quoting is conditional on it having been permitted AT THE TIME it was done AND is conditional on Art. 110 You know the section - about using in accordance with its listing (which always includes the standard at the time of mfg, which always incorporates the NEC at the time of the standard's edition issue, and which ALWAYS INCLUDES the Manufacturer's LISTED (not just what's on the label, btw, but always includes what's on the label) INSTRUCTIONS (which of course includes the LIMITATIONS and caveats therein).

IF at the time the service equipment was installed, the AIC/Shrt Circ ratiing was 5000, and was all required, those ratings were untested and untrue (based on calcultions later learned to be faulty), meantime local POCO upgrades system requires minimum vintage equipment to be protected upstream (why so many WEST of you and even on the cost adopted exterior disconnects with meter upgrades decades ago LONG before your experience) and why you still find so many (and was allowed by NEC) 3-wire feeders no ground and N & G not separated (isolated) on the "SUB" panel - and why it was ALLOWED. Its not because the 'old timers' didn't 'understand' grounding, bonding and objectional current, etc. its because it was the lesser of evils and the cost factor in addition to the two sides (distribution vs. NEC jurisdiction) The distribution side phase-in upgrades expansion vs. the little homeowner. The wheels of progress rotate faster than the wheels of safety when MONEY is involved.

The subject panelboard is over a decade older than your 'theory' of permissive alterations IN CONFLICT with the original manufacturer or its original installation. You were not permitted to install into an existing panelboard what ws not permited by the listing/labelingand vintage panelboard at the time the panelboard was manfactured. I know you're looking to justify "upgrades' moving circuits around, making room, adding taandems or twins, stuffing in a central AC circuit, additions lighting circuits, brnch circuits, electrifying a garage, finishing a basement, but it was then and remains a NO GO and is and was still WRONG.

And most importantly the NEC did not and does not "STAND ALONE" the STANDARDS contained the RESTRICTIONS and the labeling requirements and DEFINED what the "language of the label" meant. Not only the style of the NEC and the order of the NEC has changed over the years, the same has occured with the STANDARDS. The White Book was always a companion of the working electrician 'in the day'. Neither you nor J. Port ever read it (nor refer to a vintage edition). The Master should know better and the Engineer (only one qualifed to DESIGN) refer to the Standards as well as the complete data for all parts of the system.

As far as I'm willing to go with someone who doesn't understand when amperage is current limited via fusing, it doesn't magically increase load side, and that the higher the voltage the lower the amps to deliver the same power.

Wasn't permitted to use a single pole (120V) independant trip untied on the OP's panel or on the MAINS for any one's panel for a 10A, 15 A, 20A foranything OTHER than a 120 V service. (Yep, back "then" you could have a 120Vac ONLY service, commonly 30A - 60A, some (rarely) higher. They still exist, even today.

Where you can fall into the why and such is also the old standards regrding to the breakers themselves. The obsolete vintage QOs even were NOT 10,000 SSR/aic unless specificlly indicated (directly imprinted/labeled individually) most not even 7,000, questionable at even 5,000.

Schneider used to have some good info in the Q & A snippets on the old (obsolete long before they acquired ownership of Square D) XO line, don't know if they're still on the present site - but if there and in the other obsolete/old data yoou'd find qite a bit about the old NEC chpters, old stndrds, and old limitations, and the "why" so you can understand what you've previously been referred to in the old NEC editionsetc.

Hittin the hy now, the wireless is slower thn old dial-up and I'm having to type blind with the dang auto save feture kicking in constantly, Ugh.

Originally Posted by H.G. Watson, Sr.

Wrong.


...and one of the biggies you always overlook - the AIC limitations (SEE YOUR GREEN (not WHITE) book (emphasis, et. al.).

IF at the time the service equipment was installed, the AIC/Shrt Circ ratiing was 5000, and was all required, those ratings were untested and untrue (based on calcultions later learned to be faulty), meantime local POCO upgrades system requires minimum vintage equipment to be protected upstream (why so many WEST of you and even on the cost adopted exterior disconnects with meter upgrades decades ago LONG before your experience) and why you still find so many (and was allowed by NEC) 3-wire feeders no ground and N & G not separated (isolated) on the "SUB" panel - and why it was ALLOWED.


Where you can fall into the why and such is also the old standards regrding to the breakers themselves. The obsolete vintage QOs even were NOT 10,000 SSR/aic unless specificlly indicated (directly imprinted/labeled individually) most not even 7,000, questionable at even 5,000.

At the risk of throwing gasoline on the fire, H.G. I have been in business almost 30 years and consider myself rather well informed on electrical and code issues. However, I don't know what the green and white books are. I have seen the 10,000 number referenced in the past, but SSR (short circuit rating) and AIC?, 7000, 5000?

I think you loose just about everybody reading these threads with these references, which does not K.I.S.S. I find it difficult to even take the time to make it through some of these long posts and try to make sense of of it. It is apparent that you have an excellent background in the NEC and electrical theory. But, you need to find a way to really K.I.S.S. for most of us (even myself, a P.E. with two engineering degrees).

I would just have to add--Saying you don't know what the green and white book refers to as well as the numerous other NFPA standards and various building codes and how they impact the NEC is well---you might as well say you don't know that much about the NEC and certainly shouldn't be saying you are well informed on electrical and code issues. You simply cannot have a stand alone NEC since all the other standards are deeply embedded in the writing and application of the NEC. Hopefully, Mark you don't have much to do with design or installation..

NEMA standards as well as UL testing, listing and labeling are instrumental within the NEC also..

However this "deep" application of all of these is well above what an HI would need to know..

Originally Posted by Roland Miller

I would just have to add--Saying you don't know what the green and white book refers to as well as the numerous other NFPA standards and various building codes and how they impact the NEC is well---you might as well say you don't know that much about the NEC and certainly shouldn't be saying you are well informed on electrical and code issues. You simply cannot have a stand alone NEC since all the other standards are deeply embedded in the writing and application of the NEC. Hopefully, Mark you don't have much to do with design or installation..

NEMA standards as well as UL testing, listing and labeling are instrumental within the NEC also..

However this "deep" application of all of these is well above what an HI would need to know..

Roland, I have nothing to do with design and installation. My degrees are in Mechanical and Structural Engineering. I am familiar enough with the NEC to inspect and flag most issues found during a home inspection. I have never found it necessary to refer to the Green or White Books, whatever they are.

The particular panel in question seems to be an odd one. Its hard for me to really see the wiring schematic. I usually have not trouble identifying split buss panels and determining how many disconnects they permitted. going much beyond that is a bit past requirements. Also, regarding that panel, based upon its age and the small number of circuits it can contain, it would be justified to call for replacement.

Originally Posted by Mark Reinmiller

Roland, I have nothing to do with design and installation. My degrees are in Mechanical and Structural Engineering. I am familiar enough with the NEC to inspect and flag most issues found during a home inspection. I have never found it necessary to refer to the Green or White Books, whatever they are.

The particular panel in question seems to be an odd one. Its hard for me to really see the wiring schematic. I usually have not trouble identifying split buss panels and determining how many disconnects they permitted. going much beyond that is a bit past requirements. Also, regarding that panel, based upon its age and the small number of circuits it can contain, it would be justified to call for replacement.

Thanks for clarifying this. I am sure you are aware that lots of other standards and references are involve with your disciplines. It is the same for electrical.

I will have to admit HG's posts are very difficult to follow. My involvement with numerous Phd's in my lifetime has shown me this is very common for them to write in this manner. It would seem that HG has been a Phd for a good number of years. But don't ever think just because we may not follow what he is writing that it is not loaded with facts.

Originally Posted by Mark Reinmiller

Roland, I have nothing to do with design and installation. My degrees are in Mechanical and Structural Engineering. I am familiar enough with the NEC to inspect and flag most issues found during a home inspection. I have never found it necessary to refer to the Green or White Books, whatever they are.

The particular panel in question seems to be an odd one. Its hard for me to really see the wiring schematic. I usually have not trouble identifying split buss panels and determining how many disconnects they permitted. going much beyond that is a bit past requirements. Also, regarding that panel, based upon its age and the small number of circuits it can contain, it would be justified to call for replacement.

FYI,

The "White Book" is a UL reference publication. It has been used as a concordance to the handbook by those in the field for many, many decades.

A "Green Book" is trade-speak for POCO (Power Company) requirements to receive and maintain connection to the distribution system (i.e. service)/network connections co-goverened by NESC, NEC and the propiertary particulars of the distribution system.

The "Handbook" is a non-consensus publication which is produced by staff at NFPA. It is based on the instant edition of NFPA-70 as the STAFF understands it to be, an attempt edition to edition to intrepret the transitioning changes in the consensus standard. The use of terminology and phrasing is based on the limitations of the era.

Multiple dwelling reference being relied on by "those two" is in error. More currently to what was being refered to is now refered to as a "main power feeder" and NOT a (present) service equipment nor a service point as is now clearly defined.

The significance of the period (1981-1999) being grasped at, esp. the code cycles 1981 - 1990, is monumental.

Back-in-the-day text books, training courses, etc. were on average 20 years outdated regarding rudimentary "dumbed down" physics and electrical theory. Consensus building requires education and in most cases re-education as those paricipating on narrowly focused committees strugle and didn't and in many cases still don't have the ability to "keep up" with the "other" committees. Many times, in many areas, interim cycles, committees, chapters, sections even the committes drafting has gotten it wrong. The editors of the various editions of "the handbook" have on many occasions likewise "gotten it wrong".


The "handbook" is and always has been "JUST" the "handbook". It has NEVER been "authoritative".

It is somewhat akin to a vintage "first aid" manual is to a family practice physician is to an advanced practice cardiologist or cardio/thorasic surgeon.

UL has a "Green Book".

UL ELectrical Construction Materials
This book has several purposes, some of which are: (a) to obtain the names of companies which are able to provide products bearing a Listing mark or Classification marking. (b) to obtain information pertaining to the form and nature of the Listing mark or Classification mark to be used for a specific class or category of product. (c) to obtain information or special conditions applying to the product or (d) to obtain the titles and designations of Standards that have been used for investigation of products in a specific category.

The Was referring to the IEEE "Color Books" (Green, Buff, etc.) and the POCO version of Parts 1 & 3 of the NESC service requirements

Originally Posted by H.G. Watson, Sr.

The Was referring to the IEEE "Color Books" (Green, Buff, etc.) and the POCO version of Parts 1 & 3 of the NESC service requirements

IEEE barely gets an honorable mention in the NEC and certainly is not remotely related to the application of it. NESC and the NEC are essentially identical in the common areas..

That being said it would be best not to drag any references to the IEEE into a discussion about the application of the NEC.

Originally Posted by Robert Meier

Back to the topic, these types of installation are date sensitive given that the code rules have changed over the years. For example in 1981 the NEC added the wording "For existing installations" to Exception #2 of 384.16 which eliminated the new use of split-bus panelboards. Prior to that, the exception provided relief from the not more than two main circuit breakers requirement to protect a lighting and appliance branch circuit panelboard when used in a dwelling as service equipment.

Robert, I find the NEC very confusing. The 1981 NEC references not more than 2 main circuit breakers for lighting and appliance panelboards. However, that wording does back further than 1981. I see the same wording in the 1975 and 78 NEC. In the 1978 NEC handbook Figure 384-4 shows a split buss panel and indicates it is suitable as service equipment.

What am I missing? Maybe I am too impatient to read through all of the exceptions after each statement and then try to understand what they mean (I am a mechanical/structural guy).

Originally Posted by Mark Reinmiller

Robert, I find the NEC very confusing. The 1981 NEC references not more than 2 main circuit breakers for lighting and appliance panelboards. However, that wording does back further than 1981. I see the same wording in the 1975 and 78 NEC. In the 1978 NEC handbook Figure 384-4 shows a split buss panel and indicates it is suitable as service equipment.

What am I missing? Maybe I am too impatient to read through all of the exceptions after each statement and then try to understand what they mean (I am a mechanical/structural guy).

What you are missing is that in MFD or even SFD applications of the vintage of this equipment and that which is alluded to by particular applications are FED (following a a "service disconnect" by a current limiting and overload-protecting device, not necessarily limited to protect the feeder itself but limiting as to overload overall for event conditions) ahead of a dedicated or shared main power feeder, such as a riser group, which was not yet segregated/isolated N (groundED conductor) and groundING conductor, or IF isolated for the "rise" was rebonded at the "occupancy" panelboard being used as a "service equipment" - again the last point for the occupancy where N & G were bonded. (many multi-dwelling unit buldings oftentimes via a utility owned TSF in or on-site -- Not the "building" service - the occupancy service (main power feeder) and not necessarily an INDIVIDUAL one at that (again distinction with a difference: individual vs. dedicated - which is dedicated as to type not necessarily just ONE).

Four wire feeders for same were neither required nor common until decadeS later. Even risers using bonded raceway. Rebonding of multi-occupancy systems was commonplace.

Its employment as "service equipment" is NOT the service point, it is merely the last point where N & G were common (bonded). Delta breakers were legal to use on split bus single phase panels.

10-30A CBs and their circuits required series protection from actual poco service and/or limitation - overload protection to 5,000 or less unless specifically marked/labeled otherwise. 10,000 was not a standard for more than 25 years fwd.

Blue, Green, "the color books" were and remain to the engineer and planner, essential reference materials.

No excuse to not know the UL White Book. You should D/L it from UL, its free. See the Appendices for both the UL Marking Guide for Panelboards (contains numerous pre 2008 NEC references) and the Marking Guide for MCCBs. The Appendix Marking Guide for Panelboards as well as the MCCBs will discuss the concept of Type CTL (CircuiT Limiting) panelboards, a requirement which was brought into the STANDARDs in the mid-60s. Again - understanding the concept of pre-CTL or NON-CTL panelboards (enclosed or otherwise) and especially as pertaining to LoadCenters and convertable panelboards will re-emphasize the importance of being able to read and follow the vintage (and required by the circa Standard) markings, restrictions, etc. and what they actually mean. The Meanings are devined from the VINTAGE marking requirements of the UL Standard - and in that day-and-age there was only ONE listing entity - UL -- there was NO NEED for the NEC to repeat language of the standards, only to keep up with the changes for new technology, improved safety - etc. as the standards themselves advanced. That includes actual testing under load/exposure not just calculating applied theory - which was proven wrong after decades of misapplication in the mid 80s.


Understanding the NEC did NOT at the time repeat the essential elements of the UL Standards. Only recently has it taken standard lang. and extracted it into same, which UL has in kind removed such language from the individual standards.

Further, the old NEC has the information beyond Ch. 4. Definitions and terms usage distinctively different and based on IEEE dictionary/use by UL Standards - not defined by NEC.

Originally Posted by Russell Melville

Could someone comment on this SQ D panel? There are 6 breakers to disconnect the panel. Not sure how to calculate the amperage. One breaker is 50 amps and the others are less. Main entrance would support 100 amp.

Russell,

The panel is rated at 125 AMPS as listed on the manufacture tag. I am not sure what your asking when you say "how to calculate amperage". You don't calculate the amperage of any panel by adding up the breakers.