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Thread: HW Tank and AC wiring
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02-16-2012, 10:07 PM #1
HW Tank and AC wiring
the 2 happened on 2 different houses. I asked BX for both & exterior shut-off for compressor. Then both sellers argued to me. I can only say those are unusual and shock hazards but code might not regulate them. What should I talk to them? Thanks
Similar Threads:
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02-17-2012, 12:14 AM #2
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02-17-2012, 05:31 AM #3
Re: HW Tank and AC wiring
Where cable is suspended, as in, connections to furnaces or water heaters, the wire should be protected. Canadian practice is usually to install a junction or outlet box on the wall, and use a short length of AC cable or NM cable in flexible conduit to "jump" to the appliance. Stapling NM to a piece of lumber is also sometimes used.
The air conditioner is new requires an exterior wall mounted disconnect and the cable needs protection
most often met by using.
Carlon | Liquidtight Whip 1/2 Inch | Home Depot Canada
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02-17-2012, 08:48 AM #4
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02-17-2012, 10:48 PM #5
Re: HW Tank and AC wiring
If that is a exterior A/C condensing unit,(poor placement if not) the NM cable is NOT permitted in a wet or damp location,only allowed in dry location.
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02-18-2012, 07:05 AM #6
Re: HW Tank and AC wiring
Try here.
BX Cable
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02-21-2012, 12:18 PM #7
Re: HW Tank and AC wiring
For what it's worth NMC cable is not to be run in flex-----Has to do with heat---Maybe this a little to nit-picking
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02-21-2012, 02:12 PM #8
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02-21-2012, 03:00 PM #9
Re: HW Tank and AC wiring
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02-22-2012, 01:06 PM #10
Re: HW Tank and AC wiring
I don't have the code in front of me but...... This is like you need to de-rate knob and tube wiring by 2% when you cover the wire with insulation----Does anyone do that? No---OK no one I know does this-Think of this like the wire coming to your house from the utility pole is Aluminum. The utility company can use a smaller wire then you can going down the mast pipe because the wire to the pole is air cooled. The wire in the light fixture is 18 gage and you have to run a min. 14 gage to the fixture-----It's all about heat------As a Inspector would I write any of these things down? No----These things may come up on a inspector trivia contest and ................
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02-22-2012, 01:20 PM #11
Re: HW Tank and AC wiring
All answers based on unamended National Electrical codes.
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02-22-2012, 02:13 PM #12
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02-22-2012, 04:22 PM #13
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02-22-2012, 04:23 PM #14
Re: HW Tank and AC wiring
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02-22-2012, 05:03 PM #15
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02-23-2012, 01:05 PM #16
Re: HW Tank and AC wiring
It has already been stated that NM cable, FMC, BX (or AC) is not rated for outdoor use. Other considerations are whether the wiring method is UV rated, usually marked as 'sunlight resistant'.
It is the AHJ's call as to a wiring method being subject to physical damage, but some specifics are mentioned in most codes.
NM cable shall follow closely the framing or structure.
IMO, when NM leaves the framing or structure, it then needs mechanical protection. NM can be run in any conduit up to 3ft without derating.
Let us not forget protection on open ends of metallic conduit used in this manner. Also, derating does not come into play until more than 3 current carrying conductors. Most inspectors, myself included, do not consider a sheathed cable assm. as needing derating if just one stick of conduit is used for mech. prot. in applications such as feeding a furnace.
If your looking for code references for my above statements..... I don't have the time. I will check back tomorrow.
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02-23-2012, 02:32 PM #17
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02-23-2012, 05:13 PM #18
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02-26-2012, 05:05 PM #19
Re: HW Tank and AC wiring
Sorry it took me so long to get back.
I stated 3ft as the limit of length where no derating of conductors is required.
In my haste... You fellas should have jumped on me with both boots while you had the chance NEC. 310.15(2)
You can run any number of conductors in a conduit or nipple not exceeding 2ft without derating. Otherwise, more than 3 current carrying conductors require derating per NEC. table 310.15 (b)(2)(a)
My remark about '1 stick of conduit' was qualified with a IMO. In most cases there are only 2 current carrying conductors. In a few cases there maybe 2 cables sleeved in a stick of conduit down to a device box for mechanical protection. Myself as well as other inspectors I've talked with do not consider this as requiring derating unless these conductors are fully loaded.
Remember that it is heat generation we are concerned with.
Three conductors fully loaded as allowed will generate more heat than a couple of cables carrying a few amps.
I squared R loss is the heat generated by current flow (amperage). Tis why utility companies generate and send electrical energy at high voltages (less amperage). Incase requiring minds want to know: The Square of the current, times the resistance is loss in thermal energy. Notice that volts (E) is not in the equation.
Note NEC. 334.15 allowing conduits for mechanical protection in unfinished basements and crawls with the required bushings.
Note NEC. 300.4(d) requiring cables to be 1 1/4 in from the face of framing members without mechanical protection.
Note NEC. 334.30, and (b), cables shall be supported and secured except;
where fished, and no more than 4 1/2ft unsupported when feeding equipment or luminaries in accessible ceilings.
No other location is mentioned in the NEC. allowing NM cables to be unsupported that I know of.
Most AHJ's that I know do allow some applications where the cable is managed and routed in a protected manner. If done properly in our judgment, a dishwasher may fit this description although this is clearly not in an accessible ceiling.
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02-26-2012, 06:38 PM #20
Re: HW Tank and AC wiring
"Fully loaded" has nothing to do with being a reason to derate the conductors, the number of conductors in a cable/conduit/without maintaining spacing does.
Remember that it is heat generation we are concerned with.
Derating is not there for a circuit operating at full load, it is there to protect the conductors under any number of conditions.
Your position, and that of those other inspectors, is an example of inspectors making up their own code 'because they said so'.
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03-06-2012, 08:12 AM #21
Re: HW Tank and AC wiring
NM cable not a problem for water heater.
Is a problem for compressor, considered to be damp location which is prohibited use for NM cable.
Disconnect required within sight for servicing.
Hot water tank could be "within sight" of circuit breaker panel but such should be denoted at tank.
External compressor also requires a 120V receptacle for servicing.
BX?
No longer applicable.
MC, AC, etc.
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03-06-2012, 03:40 PM #22
Re: HW Tank and AC wiring
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03-07-2012, 07:26 AM #23
Re: HW Tank and AC wiring
I'm not sure what you are requesting that I explain. A hot water tank, located indoors, is an acceptable application for utilization of NM cable. I can't determine from the picture if said NM cable is properly sized, routed to tank or attached to the proper circuit breaker but I see no reason why NM cable would not be suitable for this application.
"but such should be denoted at tank"
If the means of disconnect, which is required for servicing such an appliance, is located within sight and is indeed the OCPD utilized for the branch circuit,then it is perfectly acceptable to use such as the disconnect provided that it is properly labeled at the appliance.
The following is not intended to be directed at Mr. Peck.
It is a general observation of the numerous requests made by participants of this and many other conversations regarding electrical installations.
Everyone wants a code reference for everything, mostly for the sake of arguing.
Well, guess what?
The Code is not intended to instruct individuals on a step by step basis on how to procedurally conduct the business of electrical contracting.
If you loosen a screw, does the code say it shall be re-tightened?
Many actions associated with the business of electrical installation are not specifically demonstrated within the code.
It is not entitled "Electrical Work For Dummies."
If an inspector instructs an individual to perform a reasonable task......do it.
Stop asking inspectors to prove that they are correct.
Prove to them they are not utilizing the document that governs the trade.
Again, not intended for Mr. Peck.
As a matter of personal experience, I have contractors continually argue against that which is perfectly reasonable and I simply do not have the time to research every field observation made.
Where in the Code does it say that NM cable shall not make an immediate 90 degree turn on a staple?
Where in the Code does it say that NM cable should not be stapled immediately following a framing nail plate thereby "pinching" the cable between the staple and the plate?
Maybe I just had a bad day.
Also, while on this rant, we as inspectors are not required to design your installation nor sell such a concept to your customer.
I continue to encounter licensed individuals that are completely cognizant of the fact that something is wrong with a particular circumstance or situation but feel that arguing the point in the field, in front of their customer, is demonstrative of a professional tradesperson.
I continue to encounter licensed individuals that are completely cognizant that I am compelled to enforce certain regulations such as may be set forth by the utility serving a particular area. (Yes the code has language indicating that installations shall comply with utility requirements, however; those requirements are not in the Code.)
The fact that something is not specified directly in the Code does not make it my personal opinion.
Sometimes, as a previous contractor myself with 30+ years of experience, I instruct electricians to do things a certain way because it's the right way to do it.
That's not always something that can be disseminated by a codebook.
And don't do something you know is wrong, expecting to fail and then be able to perform that which you should have done in the first place but couldn't sell your customer on it.
Not intending to offend anyone.
Just venting.
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03-07-2012, 08:12 AM #24
Re: HW Tank and AC wiring
2008 NEC, Article 334, chock-full of useful infomration regarding the use of Types NM, NMC, and NMS cable. For example:
334.24 Bending Radius. Bends in Types NM, NMC, and NMS cable shall be so made that the cable will not be damaged.
The radius of the curve of the inner edge of any bend
during or after installation
shall not be less than five times the diameter of the cable.
The draped NM to the Water Heater is not supported, it is exposed, it is not protected, and the outer surface of an electric storage type water heater is NOT a building finish.
Last edited by H.G. Watson, Sr.; 03-07-2012 at 08:20 AM. Reason: quote formatting correction
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03-07-2012, 08:36 AM #25
Re: HW Tank and AC wiring
In this situation it don't matter the wire has to be rated for the location it's being used. If it's outside it has to be wet rated. Simple fix add disconnect box on the side of the building and switch over to THWN wire in liquid tight conduit. Add GFCI outlet if an outlet is required.
And for the water heater some AHJ allow the NM cable and some require armored cable.
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03-07-2012, 03:57 PM #26
Re: HW Tank and AC wiring
Originally Posted by Richard D. FornataroOriginally Posted by Jerry Peck
Originally Posted by Richard D. Fornataro
Your statement was "denoted at the tank" and nothing is required to be denoted at the tank. Your answer was that the disconnect had to be within sight (it does not have to be "within sight", but that is one of the options for the disconnect).
Again, you stated "properly labeled at the appliance"
What needs to be labeled *at the appliance*? Nothing needs to be labeled *at the appliance* other than the appliance nameplate label.
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03-07-2012, 04:10 PM #27
Re: HW Tank and AC wiring
I was asking you to prove that you were *not* *incorrect*, but you did not prove that, you proved the opposite.
As a matter of personal experience, I have contractors continually argue against that which is perfectly reasonable and I simply do not have the time to research every field observation made.
What planet are you from, if I may ask? You are stating, not just implying, that you are a code inspector, and if you really are a code inspector you SHOULD KNOW that you DO NOT enforce *your opinion*, you are there ONLY to enforce *THE CODE*. Nothing more.
There are many code inspectors I know who say - in response the question of 'where does the code say that' - *I* want it done that way.
Whether you realize it or not, *YOU* just bought that entire job by enforcing *YOUR* *OPINION* (your way) on the contractor, and you ARE NOT performing your job as a code inspector as you should (yes, I did mean "should", as in "shall").
Your comments are so far off base that one can only conclude that you are *one of those* inspectors who tell contractor how to do things *YOUR WAY* and to heck with the code.
Just venting.
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03-08-2012, 07:42 AM #28
Re: HW Tank and AC wiring
Mr. Watson,
Thank you for the Code reference.
Which dimension is the "diameter" of the NM cable?
Seems like a silly question but it is not defined by Code.
If the definition of cable diameter is the width across the face which would include the encased wiring, then I could point out the Code section and summarily conclude that such a dimension would be called into question.
Since there is no Code definition, it becomes up to interpetation.
Diameter, as defined by Webster's is: "a line segment passing through the center of a circle, sphere, etc. from one side to the other."
Again, not attempting to be humerous here but which dimension am I to measure the line segment of?
Common sense would dictate the larger of the two dimensions but common sense is not referenced by the Code either.
I would concur with the Code reference cited, "so made so that the cable will not be damaged."
What if it's not damaged at the time of my inspection?
Can I see into the future to determine that it "might" become damaged?
As can be evidenced by this and similar forums, people like to argue minutiae.
Since you only addressed the one question I provided as an example, could we agree that not every circumstance, situation is written in the code?
The book would be difficult to carry if every bit of minutiae were indeed defined.
As to the support of the NM cable at the water heater.
It appears to be capable of being supported by the framing member adjacent to the water tank and not "draped as per your description.
One could then surmise that it does "follow the building finish."
BTW, "building finish"....not defined.
Can't really tell from the picture, however; support within 12" of exiting or entering such an appliance should be code compliant. 334.30
This inspector would not cite such.
Is it really exposed to "physical damage" if installed in such a manner in a single family home?
I can't categorically state that it is.
Physical damage is addressed in 334.15, however a scenario equivalent to the circumstance as depicted is not specifically addressed.
If we take too literal of an interpretation of the code, practically no installations would pass scrutiny.
I do however appreciate your response.
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03-08-2012, 10:26 AM #29
Re: HW Tank and AC wiring
I think we have to respect the common practice in many scenarios. this is the first time I saw NW installed on electric WH without conduit. That is why I point out for client to correct.
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03-08-2012, 01:35 PM #30
Re: HW Tank and AC wiring
Jerry Peck once again being Jerry Peck,
Did you forget to take your medication today Jerry?
I peruse this forum on an infrequent basis and have witnessed you present cogent commentary in the past, so I know that you are capable of such.
However, sporadically, you appear to have days when your commentary is merely a corruption of what others have posted with your not nots and such.
I guess that's litigious speak for I really have nothing to contribute so let me attempt to confound patrons of this forum with my over-officious opinions that have no place in reality.
I can only surmise that you are envious of my position so having nothing to offer, you choose to cast aspursions on my character and speak of my contributions in a nefarious manner.
Let me direct you to article 90.4 of the NEC.
I will paraphrase so that you can comprehend such.
The AHJ is responsibile for making interpretations of the rules.....
I'm sure that you can get someone to read the rest to you.
That means dear Jerry , that an AHJ's opinion is requisite.
And, I am the AHJ despite your disreputable accusations to the contrary.
Let me also direct you to articles 334.10 and 334.12.
Try to find where it indicates that NM cable is not suitable for use in that application.
You can't because it's BS.
Every home wired with NM cable, with an electric hot water tank is therefore non-compliant according to Uncle Jerry's rules.
Your commentary preceding this is nebulous and rambling.
Maybe that was your intent.
I, unlike your accusation, have never uttered the phrase "*I* want it done that way."
I may occasionally offer suggestions to protect contractors from "litigation consultants" who might twist the facts on a witness stand to indicate that "the plaintiff was unable to determine where the disconnect was for the hot water tank and therefore was electrocuted while attempting to work on such while it was energized."
As a contractor for 25 years, *I* would label the tank to preclude the possibility for such an occurrence.
Is it required?
Did *I* require such?
No.
I merely pointed out that I would do such.
Unfortunately, people like you do indeed exist facilitating spurious, illegitimate lawsuits that raise the costs of doing business for everyone including the customer.
What Planet am I from?
Unfortunately the same one as you.
Your rationale is skewed.
You don't exist in the real world.
You would never last in the endeavor of electrical inspector because your opinions are so far from reality that the light from reality doesn't reach you.
Have a nice life.
For the sake of patrons of this forum, I can only hope you are close to retirement.
When people show you who they are......believe them!
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03-08-2012, 03:41 PM #31
Re: HW Tank and AC wiring
Depends on how you are bending the NM cable. Bend the NM cable flatwise and the radius is based on the thickness of the NM cable, bend it widthwise and the radius of the bend is based on the width of the NM cable.
Since you only addressed the one question I provided as an example, could we agree that not every circumstance, situation is written in the code?
As to the support of the NM cable at the water heater.
It appears to be capable of being supported by the framing member adjacent to the water tank and not "draped as per your description.
One could then surmise that it does "follow the building finish."
BTW, "building finish"....not defined.
Is it really exposed to "physical damage" if installed in such a manner in a single family home?
I can't categorically state that it is.
If we take too literal of an interpretation of the code, practically no installations would pass scrutiny.
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03-08-2012, 04:22 PM #32
Re: HW Tank and AC wiring
Envious of your position? If I were in, or took your position, THEN is when I would need to start taking meds ... do you have any left over I can try out? Sheesh.
Let me direct you to article 90.4 of the NEC.
I will paraphrase so that you can comprehend such.
The AHJ is responsibile for making interpretations of the rules.....
Let me also direct you to articles 334.10 and 334.12.
Try to find where it indicates that NM cable is not suitable for use in that application.
One of your problems seems to be selective reading, or reading selectively ...
- 334.15 Exposed Work. (Oh, wait, you didn't read this far, you stopped at 334.10 and 334.12, no wonder you are having such problems reading the code.)
- - In exposed work, except as provided in 300.11(A), cable shall be installed as specified in 334.15(A) through (C).
- - (A) To Follow Surface. Cable shall closely follow the surface of the building finish or of running boards.
- - (B) Protection from Physical Damage. Cable shall be protected from physical damage where necessary by rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, or other approved means. Where passing through a floor, the cable shall be enclosed in rigid metal conduit, intermediate metal conduit, electrical metallic tubing, Schedule 80 PVC conduit, or other approved means extending at least 150 mm (6 in.) above the floor.
- - - Type NMC cable installed in shallow chases or grooves in masonry, concrete, or adobe, shall be protected in accordance with the requirements in 300.4(F) and covered with plaster, adobe, or similar finish.
I, unlike your accusation, have never uttered the phrase "*I* want it done that way."
Originally Posted by Richard D. Fornataro
YOU need to go back and read 90.4
- 90.4 Enforcement.
- - This Code is intended to be suitable for mandatory application ...
- - By special permission, the authority having jurisdiction may waive specific requirements in this Code or permit alternative methods where it is assured that equivalent objectives can be achieved by establishing and maintaining effective safety.
Special Permission. The written consent of the authority having jurisdiction.
You can't just walk up and say you want this and this, you can give SPECIAL PERMISSION ... IN WRITING ... after you have done the following:
- 110.3 Examination, Identification, Installation, and Use of Equipment.
- - (A) Examination. In judging equipment, considerations such as the following shall be evaluated:
- - - (1) Suitability for installation and use in conformity with the provisions of this Code
- - - - FPN: Suitability of equipment use may be identified by a description marked on or provided with a product to identify the suitability of the product for a specific purpose, environment, or application. Suitability of equipment may be evidenced by listing or labeling.
- - - (2) Mechanical strength and durability, including, for parts designed to enclose and protect other equipment, the adequacy of the protection thus provided
- - - (3) Wire-bending and connection space
- - - (4) Electrical insulation
- - - (5) Heating effects under normal conditions of use and also under abnormal conditions likely to arise in service
- - - (6) Arcing effects
- - - (7) Classification by type, size, voltage, current capacity, and specific use
- - - (8) Other factors that contribute to the practical safeguarding of persons using or likely to come in contact with the equipment
As a contractor for 25 years, *I* would label the tank to preclude the possibility for such an occurrence.
Is it required?
Did *I* require such?
No.
I merely pointed out that I would do such.
No matter how much you try to twist and squirm, you are stuck with what you wrote, not what you meant to write, not unless you acknowledge that what you wrote was not what you meant - but you refuse to do that. Sigh.
What Planet am I from?
Unfortunately the same one as you.
You would never last in the endeavor of electrical inspector because your opinions are so far from reality that the light from reality doesn't reach you.
And instead of spouting that this and this is what I want them to do, like you seem to do, I go by what the code says.
I am curious, are you one of those who feel that derating for "lack of maintaining spacing" is not required?
If you are (and for the others here who are of that persuasion), read this, if you don't understand why this addresses the critcalness of derating, and why derating is applicable to dwelling units and why derating is necessary, consider what this is telling you ... and then think about the distance this is addressing versus the 24" other derating starts at:
- 334.80 Ampacity.
- - The ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The ampacity shall be in accordance with the 60°C (140°F) conductor temperature rating. The 90°C (194°F) rating shall be permitted to be used for ampacity derating purposes, provided the final derated ampacity does not exceed that for a 60°C (140°F) rated conductor. The ampacity of Types NM, NMC, and NMS cable installed in cable tray shall be determined in accordance with 392.11.
- - Where more than two NM cables containing two or more current-carrying conductors are installed, without maintaining spacing between the cables, through the same opening in wood framing that is to be fire- or draft-stopped using thermal insulation, caulk, or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a) and the provisions of 310.15(A)(2), Exception, shall not apply.
- - Where more than two NM cables containing two or more current-carrying conductors are installed in contact with thermal insulation without maintaining spacing between cables, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a).
The NEC really does take derating seriously, not sure why some of you think it is not necessary when the NEC even addresses going through a 1-1/2" 2x4, and if that is foamed, sealed, etc., and there are "more than two" two conductor NM cables ... even that 1-1/2" is cause for derating.
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03-08-2012, 08:00 PM #33
Re: HW Tank and AC wiring
WOW!!
Some people have nothing better to do with their time!
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03-08-2012, 09:28 PM #34
Re: HW Tank and AC wiring
Peter Louis,
You can ignore most of Jerry Peck's and Richard Fortunato's posts, they don't apply to CANADA in the least.
When from the USA we'll refer to "Type NM", "Romex", etc. we're referring to what you call "NMD90" that is non-metallic Dry service 90 degrees C.
What we call "BX" or "AC" or Armored Cable made today, would be like your AC 90, that's a cable assembly, not a flexible conduit.
We Don't have, and never did have anything like YOUR NMWU90.
We have something similar, but ours is only allowed for burial which is UF, and our NMC isn't made despite its being discussed in our electrical code; we have nothing similar to your NMWU 90, (which is unique from both our theoretical NMC and our UF), never did.
Jumping to the water heater or to the air conditioner unit outdoors, has to be supported and protected in the CEC. NMWU 90 and NMD 90 not allowed to be exposed to direct sunlight UNLESS it is marked that it is resistant to UV and may be exposed. You are correct that you require a disconnect before the air conditoner unit.
We don't have your TECK either.
You can basically ignore all the NEC references - they don't apply to you, as you know, you're under the CEC. AS you also likely know neither NMD 90 nor NMWU 90 should be twisted up. When you have potential water in the area (outdoors, or under say a water valve, a relief or recharge port on an expansion tank, below a port to be maintained such as replacing sacrifical anode rod in storage type water heater, etc.) you also have to be mindful of water surface tension and gravity, i.e. water running along the exterior of your wiring method (e.g. a DRIP LOOP) and into your electrical installation.
HTH.
Cheers.
Last edited by H.G. Watson, Sr.; 03-08-2012 at 09:40 PM.
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03-09-2012, 07:48 AM #35
Re: HW Tank and AC wiring
Jerry Peck.
Do the authorities know you are on the loose again?
Once again your suppositions are all wrong.
Taken too far.
Subject to your self egrandized overly officious opinions.
I don't have the time or the inclination to rebuke your rambling diatribe.
Let the readers decide whom they'd prefer to inspect their homes.
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03-09-2012, 04:54 PM #36
Re: HW Tank and AC wiring
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03-13-2012, 02:32 PM #37
Re: HW Tank and AC wiring
Jerry P. So sorry we disagree
I squared R loss has everything to do with derating in a raceway just as the requirement for derating for ambient air temp has to do with, well, I squared R loss (heat).
Your comment; "Your position, and that of those other inspectors, is an example of inspectors making up their own code 'because they said so' ",
is not an example of inspectors making up their own code, but is an example of interpreting the intent as required by code.
So then, If I judge an installation as meeting the intent required by code...
I am allowed to accept the installation by code.
The 'equal or better' clause allows me to do just that.
I do not have the authority to require more or over and above the code as your statement infers.
For example: I cannot reject an installation of 3 current carrying conductors because 'I said so'. I can accept more than 3 current carrying conductors w/o derating if I calculate the heat rise will not exceed that of 3 of the same conductors fully loaded and, the fill for that raceway is not exceeded.
This is the difference between an inspector who 'knows what the code states' and one who has the respect of his Contractors.
As for HI's, they don't have this option. This is understood.
My position is covered in NEC 90-4
By special permission, the authority having jurisdiction may waive specific requirements in this code or permit alternative methods where it is assured that equivalent objectives (intent) can be achieved by establishing and maintaining effective safety.
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03-13-2012, 03:21 PM #38
Re: HW Tank and AC wiring
And you provide that special permission in writing stating that you are waiving the specific requirements and that you are allowing an alternative method, and that you have been assured that the equivalent objectives (intent) can be achieved by the alternate method, right?
Or do you just sign it off?
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05-16-2012, 03:30 PM #39
Re: HW Tank and AC wiring
Somehow I guess I missed this directed question. Sorry for the delay, I did not mean to ignore it, the oversight (not meant to be a slight) was brought to my attention today.
You were asking about the citation I quoted:
334.24 Bending Radius. Bends in Types NM, NMC, and NMS cable shall be so made that the cable will not be damaged.
The radius of the curve of the inner edge of any bend
during or after installation
shall not be less than five times the diameter of the cable.
NM Cable is not round, it is elliptical. We always use the major diameter of an ellipse, this includes when applying radius/curve/bends. We also have to use the major diameter and (do some math) apply that major diameter of the ellipse as a circular diameter when computing cross sectional volume fill in raceways, nipples, etc.
For example, as pertaining to fill/volume calculations spelled out in the Notes for Tables (inclusive) in Chapter 9, Note (9), specifically "For cables that have elliptical cross-sections, the cross-sectional area calculation shall be based on using the major diameter of the ellipse as a circle diameter."
However, I do not find that (chapt 9) applies to the application of what you are asking as pertains to the application of the code section I quoted. I believe that 334.24 is self-explanitory in the application of bending radius and direction, not being dependant on the axis bent of the elliptical cable assembly, but based always upon the major diameter of the ellipse as per stapling and securing -- going back many generations of Type NM cable assemblies and standards thereof, as I seem to recall at the moment. General bending, use, modern NM-B depends on the axis direction being bent and the opposing radius/diameter of travel through the bend.
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06-10-2012, 06:43 PM #40
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06-10-2012, 06:47 PM #41
Re: HW Tank and AC wiring
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06-10-2012, 06:59 PM #42
Re: HW Tank and AC wiring
[quote=Jerry Peck;200303]By what code?
Just looked at the code and can not find anything against. My practice is to use thhn in flex. if you run in inside flex on emt, make sure to be under 40% fill
If you strip it you no longer have a listed cable, you now have unlisted conductors.
If you strip it you have thhn wire.
Where is Manchester?
NH
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06-10-2012, 07:12 PM #43
Re: HW Tank and AC wiring
Not if you strip the outer sheath all the way off, you have unlisted cable and unlisted conductors.
Thank you - I didn't know if you were posting from Manchester England or from where, being as you are from 'this side of the pond' then the codes you are likely referring to are the NEC and the ICC codes?
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06-10-2012, 11:03 PM #44
Re: HW Tank and AC wiring
The conductors in modern NM cable are unmarked, if one strips them out to make a whip all you have is scrap copper as they are not marked as THHN, & if they were marked THHN is for dry locations only, there were some older NM cables that had the conductors marked but they were TW type & doubt anyone is using TW anymore.
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