Electrical – Do Conduit Nipples Have to Be Straight?

electricalelectrical-panelnec

Reading the 2018 NEC, near as I can tell, a conduit nipple from an electrical panel to a junction box doesn't need to be straight, only 24" or less in length. Is that right?

My house is old and the panel is in a challenging location where only the bottom knockouts are readily accessible. Because it's a split panel with meter, there aren't many knockouts in the bottom. I could run a couple more circuits through some 1 or 1.25" flex to a junction box in the crawlspace less than 24" away, and then run properly-filled conduit from that box. I think this meets code, but can anyone weigh in?

Best Answer

"nipple" is just a buzzword used to describe a pipe or conduit run that is short. Nothing says conduit runs can only be 24".

The only 24" related rule I can think of is that If the conduit run is <=24", then "thermal derate" owing to numbers of circuits in the conduit does not apply. i.e. 310.15(B)(3)(a).

However, that rule already allows:

  • up to 4 circuits in a conduit if all are 15-20A.
  • up to 3 circuits in a conduit if all are <=40A

It doesn't say that explicitly, this must be derived from 334.80, 310.15(B)(16) and 240.4(D).

So the issue doesn't come up much, except with heavy feeder (or dual EV circuits which you should not be doing anyway, ask us why).

But if your intention is to install a large number of circuits, then yes, keep that conduit <2' long between junction boxes.

As far as curves, that doesn't matter. That's not mentioned in the rule.

However, remember the rule with conduit: All access covers must be accessible forever without tools or damaging the building finish, and all conduit pipe must be built out complete before ANY wires are added in. Thus, conduit must be built to be pullable. Corners must either be sweeps, certain listed elbows right at the end, or conduit bodies whose lids must remain accessible forever.

Related Topic