If I have a 120V and a 240V single circuit (each) to an outbuilding, do they need disconnects?

Question

NEC 2017 question.

There are lots of detached garages out there that have single 120V circuits run from the house. This powers receptacles and lighting. It does not have a disconnect switch inside the building at the entry point. These exist despite NEC 225.32 seemingly requiring a disconnect. Question 1: How was it done in the past, and is this still legal?

NEC 225.30 allows multiple circuits to an outbuilding when they are different voltages.

Question 2. If a 240V circuit were added to a garage that had a legacy 120V circuit, would that oblige the new circuit to have a disconnect? Or would it require both circuits to now have a disconnect?

Question 1 is easy. Not everyone who wires a building, reads the NEC. Question two, if legacy circuit was not in code before, it can't be grandfather in. — crip659, Sep 15 '22 at 23:08
Question 1: "Chatty, open-ended questions diminish the usefulness of our site and push other questions off the front page." What's up with that??? ;) — FreeMan, Sep 16 '22 at 12:33
When was NEC 225.30 instituted? I've owned two urban homes with circuits like you describe, presumably installed during construction in the 50s. It was apparently legal at one time. — isherwood, Sep 16 '22 at 18:51

KMJ · Answer 1 · 2022-10-14T15:09:56.687

NEC 225.30 was new in the 1999 code. Earlier codes predate my expertise; my suspicion is that since it was missing from the code before then, it would have still been covered by NEC 225.8 which referenced NEC 240.40 as a simple requirement for a disconnect with no specification of location. Thus if the disconnect was provided in the structure providing the feeder, it would have been acceptable. The older codes are available on the NFPA site for free. I used the 1987 code for reference when looking at older 225.8 but didn't hunt for exactly when it started to reference NEC 240.40, which is quite permissive as written at that point.

So far as I know, if you don't touch the existing wiring you won't actually have to change it. If you're running a new 240V line it will need an accessible disconnect, and you can leave the existing 120V line be. If you're going to add a subpanel on that 240V line though, might as well move the 120V line over to it unless that invokes a bunch of other changes that you don't want to do.

Tl;dr: it looks to have been code-compliant to run a line with the disconnect in the main structure prior to 1999, and it's not compliant now.

If I have a 120V and a 240V single circuit (each) to an outbuilding, do they need disconnects?

1 Answers1