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Sub-Panel: Pass or Fail?

Do the steel conduits comply as a equipment grounding conductor all the way to the end of the circuits and the source?
Is this a subpanel for a separate building that needs a grounding electrode conductor to a grounding electrode system?
 
Is this residential? Can we see the panel label? Panel schedule? Is this panel listed as "Service only"? Isolated neutral? How are the individual circuits provided an equipment ground? How far into the building does the bundling condition exist?
 
Yankee Chronicler said:
If it's "within" the same building, why is it mounted outdoors? It appears to be mounted on a clapboard exterior wall.
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Does it matter if it is inside or outside of the same structure?
wwhitney said:
What size is the neutral conductor on the supply to the panel?

Cheers, Wayne
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I don't remember. This was in 2016. I think they are either 1AWG AL or 1/0AL
 
ICE said:
Is this residential? Can we see the panel label? Panel schedule? Is this panel listed as "Service only"? Isolated neutral? How are the individual circuits provided an equipment ground? How far into the building does the bundling condition exist?
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I don't remember. This was 2016.
 
It looks like there are at least 12 circuits (24 conductors) bunched together in one conduit. NEC Table B.2(11) limits ampacity to 70% of the value in Table B.2(1).
 
Paul Sweet said:
It looks like there are at least 12 circuits (24 conductors) bunched together in one conduit. NEC Table B.2(11) limits ampacity to 70% of the value in Table B.2(1).
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I count 12 ungrounded conductors and 11 grounded conductors. So presumably that's 10 2-wire circuits and 1 3-wire MWBC. That would make 22 CCCs, so if the conduit is long enough, the adjustment factor would be 45% per NEC Table 310.15(C)(1).

But if the conduit is under 24", no derating applies. Or if the conduit is long enough, but still less than 10% of the circuit length of any of the circuits, and no more than 10 ft, derating can be ignored. So most likely the conduit is just a short run to get inside the building to a box where the circuits separate out into multiple conduits.

steveray said:
Shared neutrals? Do the breakers need handle ties?
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Presumably the only MWBC is the 15A double pole breaker, so the common disconnect requirement would be complied with. A little hard to tell from the picture if the blue and red from that breaker are in fact grouped with a white conductor.

Cheers, Wayne
 
jar546 said:
Within the same building. Fed by RMC.
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The raceway entering the hub at the top of the box is RMC? I would expect that to just be threaded directly into the hub. The picture looks more like EMT going into a raintight connector going into the hub, although my familiarity with those fittings is limited.

If that is what the picture shows, there is some controversy about the use of a (straight threaded) connector going into a (taper threaded) hub and whether that is a violation of the NEC. I haven't made up my mind about that controversy.

Cheers, Wayne
 
wwhitney said:
Presumably the only MWBC is the 15A double pole breaker, so the common disconnect requirement would be complied with. A little hard to tell from the picture if the blue and red from that breaker are in fact grouped with a white conductor.
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If there are half the grounded conductors that there are ungrounded....How can they not be MWBC or am I just missing on that definition?
 
steveray said:
If there are half the grounded conductors that there are ungrounded....How can they not be MWBC or am I just missing on that definition?
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There are not half, you can count them in the photo. There's 11 grounded conductors (white) and 12 ungrounded (all other colors).

Cheers, Wayne
 
wwhitney said:
So most likely the conduit is just a short run to get inside the building to a box where the circuits separate out into multiple conduits.
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Oh I'm thinking that the junction box is in the attic which places it far enough away from this enclosure to bring a bundling code into play.

What about the equipment ground for the circuits?
 
ICE said:
What about the equipment ground for the circuits?
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I believe Jeff said it was raceway all the way and then that solid jumper? But maybe he was being vague to stimulate the discussion..I should probably keep my mouth shut after "Neutralgate" but whatevs....
 
This is supposed to be a subpanel. I see a bunch of neutrals connected to the neutral bus bar, but I don;t see any of the branch circuits with a grounding conductor to the grounding bus bar.
 
Yankee Chronicler said:
This is supposed to be a subpanel. I see a bunch of neutrals connected to the neutral bus bar, but I don;t see any of the branch circuits with a grounding conductor to the grounding bus bar.
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All the circuits exit via a metallic conduit with a grounding bushing on it. That metallic conduit is the single EGC for all the circuits. [At least until the circuits separate, then the EGC would similarly split up.]

Likewise, on the supply side of the panelboard, we have metallic conduit coming into a hub on the top of the enclosure. That metallic conduit is the EGC for the supply.

Cheers, Wayne
 
wwhitney said:
If that is what the picture shows, there is some controversy about the use of a (straight threaded) connector going into a (taper threaded) hub and whether that is a violation of the NEC. I haven't made up my mind about that controversy.
Click to expand...
wwhitney said:
Likewise, on the supply side of the panelboard, we have metallic conduit coming into a hub on the top of the enclosure. That metallic conduit is the EGC for the supply.
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That tapered hub with straight threads forced into it is two things. 1. Not water tight. 2. A code violation that negates it as a EGC.

Under what circumstances would the circuit grounds mate up with the metallic conduit?
 
ICE said:
That tapered hub with straight threads forced into it is two things. 1. Not water tight. 2. A code violation that negates it as a EGC.
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I certainly agree that if you use a straight-threaded raintight connector into female tapered threads, and the connector jams before the sealing gasket is properly compressed, it won't be water tight.

On the EGC question I'm a bit less decided--seems like wrench tight threads would provide a good connection whether straight and tapered are mixed or not. But I guess primarily it's a UL 514B "Conduit, Tubing, and Cable Fittings" question, straight thread connectors appear to only be fault tested with an enclosure or steel plate simulating an enclosure. So if it would work fine, it may not have been tested to work, and so should not be allowed.

But looking at the photo it appears to me that the yellow gasket may be properly compressed, in which case we may have something different here. There are other types of connectors, like threadless rigid connectors (post #3 says the supply is in rigid conduit) or tapered thread EMT connectors (if post #3 is wrong).

The upshot is that it is worth checking what the connector used is and whether it can properly be used with a hub.

Cheers, Wayne
 
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