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#200839 - 04/21/11 08:30 PM detached structure disconnect and 3 way switching
Niko Offline
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Registered: 08/17/06
Posts: 356
Loc: Campbell, CA
A detached structure (garage) with a feeder must have a disconnect.
having said that, the detached structure can not have a 3 way switching that has one 3 way switch in the separate structure and one 3 way switch in the house. Unless the circuit originates from the panel at the structure.
Am i correct?


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#200841 - 04/21/11 08:51 PM Re: detached structure disconnect and 3 way switching [Re: Niko]
George Little Offline
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Registered: 01/18/04
Posts: 1488
Loc: Michigan USA
Short answer: No

Your not being clear on the term structure. It's not possible to have a circuit originate at a detached structure. I'm assuming the detached structure is the garage and the house is the other structure. One could argue that the house is detached from the garage and vice versa. Assuming the house is the main structure and it has the panel in it, than the other structure could be a detached structure maybe a shed or garage and it could have a 3-way switch in it that could qualify as it's disconnect.


NEC 225.36


Edited by George Little (04/21/11 08:53 PM)
Edit Reason: Spelling correction
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#200842 - 04/21/11 10:07 PM Re: detached structure disconnect and 3 way switching [Re: Niko]
Niko Offline
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Registered: 08/17/06
Posts: 356
Loc: Campbell, CA
The detached structure (garage) has a feeder from the main house and a panel with a main disconnect. One of the lights on the detached structure has a (2) 3way switch that one of them is installed in the main house.
My question or code violation is if the main disconnect is turned off at the garage then potentially the garage still has power because of the 3 way switch that is installed in the house.
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#200843 - 04/21/11 11:08 PM Re: detached structure disconnect and 3 way switching [Re: Niko]
gfretwell Offline


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Registered: 07/20/04
Posts: 9038
Loc: Estero,Fl,usa
I understand Niko's point. If the 3 way is not fed from the out building the 3 way switch will not disconnect all ungrounded conductors so it is not a disconnect. I suppose you could put a 2 pole switch on the travelers grouped with the other disconnect.

I know it is "legal" but unless the switch is grouped with the disconnects, I am not sure how.


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#200845 - 04/22/11 07:17 AM Re: detached structure disconnect and 3 way switching [Re: Niko]
George Little Offline
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Registered: 01/18/04
Posts: 1488
Loc: Michigan USA
Okay Niko, I understand now. Sorry I couldn't picture it at first. Then my follow up answer would be that possibly you have a violation of 225.30 and that's exactly what you said in your opening post. I agree with your statement that the circuit should originate from the sub-panel in the detached building, in this case the garage.



225.30
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#200846 - 04/22/11 07:36 AM Re: detached structure disconnect and 3 way switching [Re: Niko]
Niko Offline
Member
Registered: 08/17/06
Posts: 356
Loc: Campbell, CA
Thanks guys.
I guess theoretically speaking the installation will not be a violation if the switch in the house can be locked and the the other 3 way switch on the garage will be a disconnect.

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#200848 - 04/22/11 07:50 AM Re: detached structure disconnect and 3 way switching [Re: Niko]
harold endean Offline
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Registered: 02/16/02
Posts: 2233
Loc: Boonton, NJ
Maybe you can isolate the 3 way switch in the house and put a tiny label on it. That might say, "Garage light". This way it wouldn't be ganged together with switches whose power originates from the house.

Inside the box, or behind the switch plate, you could write that power comes from the garage.
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#200849 - 04/22/11 08:40 AM Re: detached structure disconnect and 3 way switching [Re: Niko]
George Little Offline
Member
Registered: 01/18/04
Posts: 1488
Loc: Michigan USA
Nope- I don't see any way out of this one. You definitely have a situation where you are feeding the garage with two sources of power. You have the feeder and also a branch circuit. Clear violation of 225.30. The only out of it is to re-wire the three way circuit so that the power originates out of the panel in the garage.

Harold I understood that the panel in the garage is fed from the house and has a main disconnect in the panel, and that additionally there is a branch circuit originating from the house for lighting on/in the detached garage, with a three way switch located in the garage. The hazard could be that a person could turn off the main in the sub panel and then go work on the three way switch. Clear possibility. 225.30 is the code reference. Red Sticker under my inspection.
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#200851 - 04/22/11 08:46 AM Re: detached structure disconnect and 3 way switching [Re: Niko]
HotLine1 Offline


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Registered: 04/03/02
Posts: 6776
Loc: Brick, NJ USA
I have to agree with George!
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#200855 - 04/22/11 10:41 AM Re: detached structure disconnect and 3 way switching [Re: Niko]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9038
Loc: Estero,Fl,usa
I am not sure it is really 2 sources of power, both come from the main house. You are allowed up to 6 disconnects. The only issue I see is they have to be grouped. The exception George pointed out in his first answer clearly says "3 and 4 way switch loop". The trick is getting the 3 way close enough to the sub panel to be grouped and still be useful as the light switch. That is why I suggested a 2 pole in the travelers at the point on entrance marked disconnect and the 3 way where you need it. That is still pretty ugly because most people would assume it was a 4 way.

If you go the other way, I agree with Harold, I would label the switch. I do have a situation in my house I know is not legal but it is well labeled and "come and get me copper". I have a separate receptacle circuit, fed from the main panel in the garage next to the sub panel in my house. It is just so I will have light if I am working on the house power with the feeder turned off in the garage. It was actually the original circuit that fed the garage before I flipped everything on a service upgrade.
It has a red cover and a label saying it is "fed from the garage".
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