I'm wiring a detached garage/ apartment that needs a 100 amp sub panel and a 3 way switch run to the existing house. Can I run the wires for the switch leg in the same conduit as the feeder assuming the conduit is sized and derated properly. I've never run any other wire with the feeder before, so I'm curious if it's allowed. I searched the NEC, but couldn't find any reference. Thanks for the help.
Eagle, I would say 10-4 to Roger. The only limitations that would even come close to what you are "driving at" would be the rule that does not allow other circuits to be pulled in the service entrance raceway. In the '99 code it was 230-7, but I'm not sure about the '02 code. I would go get my '02 code book and look it up for you, but my backside is surgically implanted in this chair in front of my computer. There are very few exceptions to 230-7.
Somebody get me a doctor, Doc
The Watt Doctor Altura Cogen Channelview, TX
Re: Branch circuit with the feeder???#11439 07/11/0209:36 PM07/11/0209:36 PM
I don't see a problem with what you want to do. I assume the main service is at the house and your are running a feeder from the house to the detached garage. If this is the case make sure you feed the 3-way switch from the garage panel. If you were to feed it from the house this circuit would still be energized when the main breaker in the garage is off.
Re: Branch circuit with the feeder???#11440 07/12/0207:08 AM07/12/0207:08 AM
I realized the other day, a rule that I haven't considered in quite some time. I'm not sure that it would apply to your situation, and I can't recall where it would be found in the code. I'm sure others here can help. It used to be a violation of the code to use a panel as a raceway, and unless I'm mistaken, you may run into that situation here. In order to avoid that circumstance, I would set a j-box before you get to the panel, and "drop your branch circuit off" in it. Sorry I didn't get back with this information sooner, but I just didn't think about it until the other day. I would check with George Corron, Joe Tedesco, or Scott35 those guys know the code better than I know my wife.
Sorry honey, but it's the truth, Doc
The Watt Doctor Altura Cogen Channelview, TX
Re: Branch circuit with the feeder???#11442 07/15/0209:48 AM07/15/0209:48 AM
Your are right and I should have brought that up in my reply. He should not run the switch legs through the panels and should install J-boxes at each end of this feeder. Also make sure these boxes are sixes properly. They need to be sized based on the feeder raceway size not the switch leg raceway or cables.
Re: Branch circuit with the feeder???#11443 07/15/0210:06 AM07/15/0210:06 AM
The code does not prohibit using the panel as a raceway. Look at 404.3(B) which sends you to 312.8.
312.8 Enclosures for Switches or Overcurrent Devices. Enclosures for switches or overcurrent devices shall not be used as junction boxes, auxiliary gutters, or raceways for conductors feeding through or tapping off to other switches or overcurrent devices, unless adequate space for this purpose is provided. The conductors shall not fill the wiring space at any cross section to more than 40 percent of the cross-sectional area of the space, and the conductors, splices, and taps shall not fill the wiring space at any cross section to more than 75 percent of the cross-sectional area of that space.
Re: Branch circuit with the feeder???#11444 07/15/0210:25 AM07/15/0210:25 AM
I realize the code does not technically prohibit this installation but many inspectors will give you a hard time when they see splices or wires passing through the panel. Commercial panel boards typically have very large gutters so a few extra wires would not be a problem but some of the load centers used for residential projects are pretty small. I don't think it would be worth an argument with an inspector or trying to figure out the gutter area of the panel. Since we don't know the size of his panels or the number of conductors passing through I felt it was better to recommend using j-boxes for this installation but he would most likely be code compliant without them.
Re: Branch circuit with the feeder???#11445 07/15/0210:50 AM07/15/0210:50 AM
See, I told you somebody would step up to the plate. Thanks Don, and Curt for helping me out. Its a matter of choice for you Eagle. Legally, you can use the panel as a raceway as Don noted, but as Curt pointed out, is it worth dealing with an inspector who may decide to turn you installation down because you violated the 40% rule?