Question regarding branch circuits wire sizing

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infinity said:
With the information provided you cannot determine what you're asking. The engineering note is quite clear, is there a specific reason why you need to know this?
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Well i want to know if homerun and circuit run are sized proper to have 3 percent voltage drop.

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codequestion said:
Well i want to know if homerun and circuit run are sized proper to have 3 percent voltage drop.
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And a default load for each receptacle has been provided because it is not being given.

Load at each receptacle, length from panel to that receptacle (X 2), V=IR, relative to the gauge/length of wire. Add them up.

What am I missing?

After receptacle 1, you have the 100' of #10, plus the amount of #12 between the first one and the one currently being calculated.
 
codequestion said:
Well i want to know if homerun and circuit run are sized proper to have 3 percent voltage drop.

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Oh for petes sake.:slaphead:

What is/are your LOAD(s)?

If you really need to know VD, but yet don't know or can't at least guess a ballpark figure of might be plugged in, you're back to square one.

Reread the posts.:)

Why the need for the info in the first place? As said above if this is for a specific piece of equipment (dedicated/IBC situation) fed by a long run, then yes it could be important to know this. But if this is just to consider VD between a few moderate length runs between a couple or three gen use recs, its a waste of time.
 
augie47 said:
There are only a few specific where the NEC requires voltage drop to be considered (Art 695 & 647 come to mind). Voltage drop on "standard" light & receptacle circuits is a design issue although an un-enforceable FPN at 210.19 does provide some guidance.
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I agree that the NEC only requires voltage drop to be taken into consideration in a few places. However, if your jurisdiction adopts or enforces ASHRAE 90.1, voltage drop is limited per 8.4.1 (2009 version)
 
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packersparky said:
I agree that the NEC only requires voltage drop to be taken into consideration in a few places. However, if your jurisdiction adopts or enforces ASHRAE 90.1, voltage drop is limited per 8.4.1 (2009 version)
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Drawings use iecc 2015 not asharae and AHJ has nec requirement for VD not other codes.

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codequestion said:
Drawings use iecc 2015 not asharae and AHJ has nec requirement for VD not other codes.

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The AHJ may adopt the informational notes pertaining to voltage drop into local amendments. If not, the voltage drop requirements in the informational notes may not be enforceable.
 
codequestion said:
Huh? Informational notes are not part of codes in NEC 2014?

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ActionDave said:
They are considered explanatory material and are not enforceable language. 90.5(C)
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^^^^^^^^
This

Codequestion, as ActionDave said, those notes aren't considered enforceable.

There have been threads here where folks have butted heads over this- somebody will think that they have a viable passage b/c of an IN, only to be shot down w/ 90.5
 
From the first page of the NECH.

The commentary and supplementary materials in this handbook are not a part of the NFPA Document and do not
constitute Formal Interpretations of the NFPA (which can be
obtained only through requests processed by the responsible
technical committees in accordance with the published
procedures of the NFPA). The commentary and supplementary
materials, therefore, solely reflect the personal opinions of the
editor or other contributors and do not necessarily represent the
official position of the NFPA or its technical committees.
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Roger
 
steve66 said:
Yes, you can reduce the wire size going to the second or 3rd or any of the other receptacles.

There isn't anything in the NEC that specifically says you can do this, but its not prohibited anywhere.

Generally, the NEC requires you to size the wires for the branch circuit breaker (lets assume its a 20A breaker for this case.) So you have to use a minimum of #12 wire.

If you increase part of the circuit to a larger wire size for voltage drop, that's fine. It doesn't have any effect on the required wire sizes for the rest of the circuit.

Note however that there is a code section that requires the ground wire to be increased in size when the hot wires are increased in size. So in this case, the ground wire would also be a #10 for the portion of the circuit where the wires are #10.
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So what about if I use #12 awg in recptacle 2 and recptacle 3 then I would have to use #12 Awg equipment ground and not #10 awg equipment ground?

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codequestion said:
So what about if I use #12 awg in recptacle 2 and recptacle 3 then I would have to use #12 Awg equipment ground and not #10 awg equipment ground?
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You wouldn't have to use #12 for these but you could, you could stay with the #10, read 250.122(B)

Roger
 
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