Thread: Distribution panel rating

This is a disconnect panel for a steam shower generator. The distribution panel is rated for 70amps and the breaker is a 70amp. However, the feeders for the box are supplied from the service panel, whichi is a 200 amp disconnect. Also the ground in the distribution panel is not bond. Does the ground need to be bonded to the panel and the panel rating match that of the service. Single family home built in 09

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Originally Posted by mathew stouffer

This is a disconnect panel for a steam shower generator. The distribution panel is rated for 70amps and the breaker is a 70amp. However, the feeders for the box are supplied from the service panel, whichi is a 200 amp disconnect. Also the ground in the distribution panel is not bond. Does the ground need to be bonded to the panel and the panel rating match that of the service. Single family home built in 09

Here is what is used in NC so in NC you would be ok. Also the 70 amp panel needs to be bonded.


(1) Taps Not over 3 m (10 ft) Long.

Where the length of
the tap conductors does not exceed 3 m (10 ft) and the tap
conductors comply with all of the following:
(1) The ampacity of the tap conductors is
a. Not less than the combined calculated loads on the
circuits supplied by the tap conductors, and
b. Not less than the rating of the device supplied by
the tap conductors or not less than the rating of the
overcurrent protective device at the termination of
the tap conductors.
(2) The tap conductors do not extend beyond the switchboard,
panelboard, disconnecting means, or control devices
they supply.
(3) Except at the point of connection to the feeder, the tap
conductors are enclosed in a raceway, which shall extend
from the tap to the enclosure of an enclosed
switchboard, panelboard, or control devices, or to the
back of an open switchboard.
(4) For field installations where the tap conductors leave
the enclosure or vault in which the tap is made, the
rating of the overcurrent device on the line side of the

tap conductors shall no

Based on the 2nd pic I thought the OP was showing the breaker that feeds the small panel. If that is the case this is not a tap. Matt can you clarify?

Matt, why would you think all the panels need the same rating as the service?

I get the impression that the small panel was being fed from the lugs on the bottom of the bus bars. Not sure now...

The panel is being fed by the lugs at the bottom of the service dissconnect. Those lugs are on the bus bar which is controlled by a 200 amp breaker. So if the feeder cables supplying the distribution panel are connected to a 200 amp disconnect doesnt the panel need to have a rating of 200 amp, not a 70 amp rating.

First problem: Please tell me that the panel is not being used with a retasked White as a feeder! Failure #1, You cannot re task a white wire to be used as a feeder!

what if you wrap black tape around it

Originally Posted by mathew stouffer

The panel is being fed by the lugs at the bottom of the service dissconnect. Those lugs are on the bus bar which is controlled by a 200 amp breaker. So if the feeder cables supplying the distribution panel are connected to a 200 amp disconnect doesnt the panel need to have a rating of 200 amp, not a 70 amp rating.

The 10' tap rules applies so you should be okay. Read (1)(1) a&b in my first post carefully...

As far as the white conductor goes, it is marked black. I would let the electrician decide if that's a problem.

I can't see how this is correct if the distrubiton panel has a max rating of 70 amp and the feeders are tapped into a 200 amp bus bar. What am I missing ?

(1) The ampacity of the tap conductors is

a. Not less than the combined calculated loads on the circuits supplied by the tap conductors, and
(in this case 70 amps)

b. Not less than the rating of the device supplied by
the tap conductors or not less than the rating of the
overcurrent protective device at the termination of
the tap conductors.
(in this case #6...rated at 75 amps being protected by a 70 amp breaker)

Originally Posted by mathew stouffer

I can't see how this is correct if the distrubiton panel has a max rating of 70 amp and the feeders are tapped into a 200 amp bus bar. What am I missing ?

Being as this is a tap, the OCP is supplied at the load end in the small panel.

The ground should be on a ground bar, not the neutral buss. The neutral buss would be unused on the 240 volt circuit.

Oh that is what is was missing

Additionally, the equipment grounding conductor looks like it's a #10, which is only good on a 60 Amp circuit or less. 70 Amp requires the use of a #8.

The equipment ground also doesn't look like it's bonded to the enclosure for the the 70 Amp breaker.

Originally Posted by mathew stouffer

The panel is being fed by the lugs at the bottom of the service dissconnect. Those lugs are on the bus bar which is controlled by a 200 amp breaker. So if the feeder cables supplying the distribution panel are connected to a 200 amp disconnect doesnt the panel need to have a rating of 200 amp, not a 70 amp rating.

Matt

Lets see if I can explain when you need a panel rated the same as the service equipment.

The service equipment panel in your situation has feed thru lugs on the bottom. If I decide to feed another panel from those lugs and the feeders terminated to the feed thru lugs supply a MLO panel and do not terminate to any overcurrent device in that panel then you would need a panel rated equal to the rating of the service equipment. Simply because the 200 amp 'main breaker' in the service equipment is also the ocpd for the feeders to the mlo panel. So those conductors need to be sized to the 200 amp service equipment as well as the panel itself..

In your situation those conductors land on a 70 amp breaker serving as the disconnect and protection to branch circuit conductors for the steam generator. That breaker limits the current that will be fed thru the service equipment to supply the steam generator and therefore the conductors terminated to the feed thru lugs serving the 70 amp panel will never see more current than the trip out specifications of the 70 amp breaker. So you would be allowed to size them according to the tap rules that apply.

Hope that makes sense.

Most such of this type and size have ratings which would limit to a 60A Max application. You were there and read the label, reviewed the diagram, I can't make it out in your photos. Although that 70 amp 2P breaker is likely rated to withstand SCRs, etc. sufficient to have been located in the Service Equipment, it is not likely that the distribution panel's buss is equivalently rated, therefore, and especially if not, should not be tapped directly off the buss from the service equipment using that cable at that size - due to temp ratings, short circuit ratings, etc.

Sandwiched & surface mounted between two other panel cabinets, both of which are deeper, that is protrude beyond the face of this center one.

As shown in the photo below there appear to be serious encroachments to the the working space clearance zone and the dedicated equipment space zone. Minimums for the zones extend to the minimum height from ground or grade and/OR to the height of the equipment itself, whichever is higher. Appears to also be a width working space /clearance "issue" - This three-foot deep, 30 inch wide minimal zone "box" of working space may begin on either side of the equipment but this middle "panel" doesn't appear to have the minimum regardless of which side you begin the "zone" as the projection of the neighboring equipment exceeds that of the center cabinet and panel equipment pictured, and projections exceeding the face on either side do not meet metering equipment exceptions.



May also be a general proximity (side) clearance enroachment issue (mfg & utility) with the presumed lateral supplied combination equipment on the Left. The size appears to be under the minimum allowable for those lugs.

This does not appear to have been orignal to the installation (note ghosts in re: stain on siding above/behind this center panel). To have gone through the extra effort to be unsafe re clearances, etc. JUST TO AVOID GETTING A GE BRANDED CIRCUIT BREAKER to install in the panel at the left in the first place(guess the "steam shower guy" only had a Square D)! when could easily hav installed a 70A 2-P breaker on service equipment panel and entered the same structural wall a mere 8 or so inches to the left. Does not the Steam Shower generator require a 120/240V GFCI supply?

No you may not "UN"identify or "repurpose" white, gray or "nautral" with tape, paint or otherwise as a hot tap.

I am curious regarding the (zip cord? exterior low voltage cable for burial?)presence of the cord/cable on the wiring Left trough service panel first photo.


I am also concerned regarding the two 100A circuits (Red/Black 240V bare ground shared with RWG on L and Blk/Blk-Bare N w/insulated ground on Right) if I'm piecing the two photos correctly, which are leaving the panel and entering the structure from the back wall of the "service" panel, and the wiring methods/wiring/cable type, clamps (lack), etc.; mounting hardware - type, undersize, rusting screws, kckots, etc.) as shown at the lower half of this photo - esp. as you indicate built 2009, it seems there must have been many modifications post AHJ inspection, if there was one.

Conductors #6 and smaller may not be re-identified,except for switch loops. Larger conductors may be taped or painted at their terminations. You will not find the larger conductors with green or white insulation in many cities or electrical suppliers, so reidentifying them is allowed by the code. It makes no difference if they are feeders or not.
These conductors fall under the 10' tap rule and are compilant if the conductors are rated for 70 amps at the temperature rating of the breaker. If the breaker is marked at 75*C. it requires a #4 CU conductor, if it is not marked, then it is only rated at 60*C. and requires a #3 CU conductor. Breakers over 100 amps are rated 75*C. I am not aware of any breakers sized 100 amps or less, that are rated 90*C. Do not confuse the termination ratings on the breaker with the 40*C rating that is also shown on the body.

Even though the wire may be rated for 90*C, it has to be limited by the temperature rating of it's termination points.

All metal parts of an electrical system must be bonded and grounded.

NEC 200.7C2, 215.12C, 240.21B, 110.14C, Table B.310.1, 250.4A

I believe that panel is 200-amp feed-thru 8/16 space that will hold a either 8 full size or up to 16 wafer size breakers or a combination of both. With a little reconfiguring the added 70-amp breaker and enclosure may not even be needed.

I don't believe this qualifies as a "tap" so the tap rules wouldn't apply! How do justify this as a "tap"? Somebody please enlighten me!

Originally Posted by Lou Romano

I believe that panel is 200-amp feed-thru 8/16 space that will hold a either 8 full size or up to 16 wafer size breakers or a combination of both. With a little reconfiguring the added 70-amp breaker and enclosure may not even be needed.

I don't believe this qualifies as a "tap" so the tap rules wouldn't apply! How do justify this as a "tap"? Somebody please enlighten me!

See NEC 240.2 for a definition of tap conductors.
The code requires the use of a properly sized overcurrent device where a conductor receives it's supply. There are exceptions to this rule to allow connection of a smaller ampacity conductor to a larger ampacity conductor. These are regulated by the tap rules. For subpanels, you would use Feeder Taps found in NEC 240.21.

Although the panel may be rated for 16 half size breakers, all the loads are 240 volt two pole. You will not find half-size two-pole breakers, since it would require the breaker to clip onto two separate bus bars. Tandem breakers only use one phase. You could install four half size breakers and use handle ties, It will cost more to add the breakers, for materials and labor, and you would have not made any significant improvement to quality of the installation.

Even a feed through panel is required to follow the tap rules if the sub feeds are smaller than the feeders.

relocate a few breakers and use the 1" breakers as shown below and everthing else can be removed.



"+v25+"

Originally Posted by Scott Cook

Conductors #6 and smaller may not be re-identified,except for switch loops.

NEC 200.7C2,

You need to go back and re-read the code you think yo are quoting.

Read ALL of 200.7(C).

Originally Posted by Jerry Peck

You need to go back and re-read the code you think yo are quoting.

Read ALL of 200.7(C).

You're right Jerry. I know what I meant, but I got off the track talking about romex somehow.
200.7(C) Exception (1) allows for remarking neutrals inside of cable assemblies (NM romex, etc).
I did not state it completely, in that "remarking neutrals" is allowable for more situations than just switch loops when using cable assemblies such as NM.
I orginally thought those were individual conductors, but now I think it may be romex in the photo.
200.6A does not have any provision for remarking at the terminations of 6 awg and smaller conductors of the THHN type, since it requires a continuous color it's entire length. Remarking individual conductors is not given as an option in this section.
If we are looking at NM cable in a raceway it is wrong. If it is individual THHN conductors it is wrong to remark them. Either way, the wire is too small.

Originally Posted by Scott Cook

For subpanels, you would use Feeder Taps found in NEC 240.21.

Your not tapping a feeder in this scenario you are tapping off the busbar. I am not questioning the feeder size I'm questioning where the feeder is tapped from. It has always been my understanding that you don't tap the switch you tap the conductor. So if you came off of those feed thru lugs with 2/0 copper and then tapped those conductors I wouldn't question it. But that is not what is depicted here.

Truly I can see the arguments both ways so suffice it to say, I wouldn't do it this way!

Originally Posted by Lou Romano

Your not tapping a feeder in this scenario you are tapping off the busbar. I am not questioning the feeder size I'm questioning where the feeder is tapped from. It has always been my understanding that you don't tap the switch you tap the conductor. So if you came off of those feed thru lugs with 2/0 copper and then tapped those conductors I wouldn't question it. But that is not what is depicted here.

Truly I can see the arguments both ways so suffice it to say, I wouldn't do it this way!

Lou

Tap conductors are defined in 240.2 of the 2002 NEC as: Tap Conductors “As used in this article, a tap conductor is defined as a conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4.”

Nothing in that definition says you must tap a wire conductor. It simply says a point of supply which would be the bus bar. You could have feeders connected to those lugs or tap conductors ... do you see the point I'm making or would you like further explanation?