Indoor wire in conduit to detached garage

smithl3 · Mar 3, 2012

Hey all,

I am getting my garage structure up this week and planned on pulling my wire feeds through conduit I already buried. I have 2" conduit between the house and garage, about 100', with #2 Al wire feed for a 100 amp sub panel. I setup a few switches in the house to control the exterior lights on the detached garage and had some questions.

I am planning on running two 14-3 feeds along with the #2 main panel feed to control the two exterior lights. This way I can have a three way switch at both the house and garage to control them. Can I use interior 14-3 to pull through the PVC conduit or should I use burial cable for moisture concerns?

Also do you see any issue with using the same conduit for both the main feed as well as these two added power feeds?

The power feed is coming from the house panel and is a 15 amp breaker for 4 single bulb exterior lights and one halogen spotlight. Should I use 12 gauge for so few lights?

Thanks for all the feedback in advance,
smithl3

Alchymist · Mar 3, 2012

smithl3 said:
Hey all,

I am getting my garage structure up this week and planned on pulling my wire feeds through conduit I already buried. I have 2" conduit between the house and garage, about 100', with #2 Al wire feed for a 100 amp sub panel. I setup a few switches in the house to control the exterior lights on the detached garage and had some questions.

#2 @100 amps is a little light.

I am planning on running two 14-3 feeds along with the #2 main panel feed to control the two exterior lights. This way I can have a three way switch at both the house and garage to control them. Can I use interior 14-3 to pull through the PVC conduit or should I use burial cable for moisture concerns?

Only one circuit is allowed between house and detached building. No, you cannot pull 14-3 in buriedconduit.

Also do you see any issue with using the same conduit for both the main feed as well as these two added power feeds?

Yes.

The power feed is coming from the house panel and is a 15 amp breaker for 4 single bulb exterior lights and one halogen spotlight. Should I use 12 gauge for so few lights?

Thanks for all the feedback in advance,
smithl3

Best bet is remote control like a garage door opener to control lights, or perhaps a Smarthome system or similar.

Aceman · Mar 3, 2012

Alchymist said:
Only one circuit is allowed between house and detached building.

225.30(D) mentions allowing an extra circuit if it's for controlling outside lights.

Alchymist said:
No, you cannot pull 14-3 Romex in buried conduit.

UF would be okay. I'd rather run it in a seperate smaller conduit though....

Alchymist · Mar 3, 2012

Aceman said:
225.30(D) mentions allowing an extra circuit if it's for controlling outside lights.

UF would be okay. I'd rather run it in a seperate smaller conduit though....

IF the power for these lights is taken from the garage sub panel, it's "legal"; frowned on in many areas and against local code in some. IF the power is from the house panel, then no, it's not. OP said 14-2 FEEDERS ........

Norcal · Mar 3, 2012

Aceman said:
225.30(D) mentions allowing an extra circuit if it's for controlling outside lights.

Here is a copy & paste from the 2008 NEC:

(D) Different Characteristics. Additional feeders or
branch circuits shall be permitted for different voltages,
frequencies, or phases or for different uses, such as control
of outside lighting from multiple locations.

UF would be okay. I'd rather run it in a seperate smaller conduit though....

Agreed, but I hate UF.

(Pipe & wire is IMHO the only way to go).

pattenp · Mar 3, 2012

If the #2 is USE then it's only rated for 75A if it's XHHW or THWN then you can get away at 90A. To get the full 100A you need #1/0 AL USE or #1 AL XHHW or THWN

smithl3 said:
Hey all,

I am getting my garage structure up this week and planned on pulling my wire feeds through conduit I already buried. I have 2" conduit between the house and garage, about 100', with #2 Al wire feed for a 100 amp sub panel. I setup a few switches in the house to control the exterior lights on the detached garage and had some questions.

I am planning on running two 14-3 feeds along with the #2 main panel feed to control the two exterior lights. This way I can have a three way switch at both the house and garage to control them. Can I use interior 14-3 to pull through the PVC conduit or should I use burial cable for moisture concerns?

Also do you see any issue with using the same conduit for both the main feed as well as these two added power feeds?

The power feed is coming from the house panel and is a 15 amp breaker for 4 single bulb exterior lights and one halogen spotlight. Should I use 12 gauge for so few lights?

Thanks for all the feedback in advance,
smithl3

Aceman · Mar 3, 2012

Norcal said:
I hate UF

Me too!

pattenp said:
If the #2 is USE then it's only rated for 75A if it's XHHW or THWN then you can get away at 90A. To get the full 100A you need #1/0 AL USE or #1 AL XHHW or THWN

I've debated this with you before, so all I'll say is if it's multi-rated as RHH RHW and installed in conduit, it's 90 amp wire.

pattenp · Mar 3, 2012

I don't disagree with you on the multi-rated USE/RHH/RHW. I'm just citing the code for USE when installed as an underground feeder it has to be sized from the 60C column which #2 AL would be 75A. Article 338 that covers service entrance cables types SE and USE don't even reference the insulation types such as THWN RHH RHW. The article just states the requirements for SE and USE.

I should have listed RHH and RHW along with the THWN and XHHW @ 90A.

Aceman said:
Me too!

I've debated this with you before, so all I'll say is if it's multi-rated as RHH RHW and installed in conduit, it's 90 amp wire.

Charles (in GA) · Mar 3, 2012

Its rare nowdays to find single rated wire. It almost always carries multiple ratings, one just needs to be sure of what.

One very popular brand, whose home office is right here in west Georgia, is Southwire. The pic below shows their 2-2-2-4 AL. It is rated USE-2, RHH, RHW, so lots of choices to go on here.

Charles

gnxtc2 · Mar 3, 2012

UF=job security

Billy T.
[email protected]

smithl3 · Mar 4, 2012

The exact wire I have is XLPE USE-2 UL aluminum three wire. Black insulated with one neutral wire with yellow stripe. A local electrician said I can ground locally to the garage with a ground rod and barn wire at the sub panel. As far as the breaker size, I had a 100 amp and planned on using it, if the wire I have isn't sufficient I can certainly downsize to a 75 amp, that would still be plenty for my needs in the garage.

As far as running the 14-3 wire in with this main power feed, am I correct in sayings can do it only if it is fed from the garage? If that is the case I don't see the logic, but code is code.

I have a separate conduit for data cables but I didn't want to put any power cables in there for the concern of messing with the data signals.

Not sure how to control my lights.... I definitely want then hard wired.

Thanks for all the info guys,
smithl3

pattenp · Mar 4, 2012

I know for a fact it's against code to run more than one power source/feed to an outbuilding. You can run within the same conduit as the power feed a switch loop that comes back from the outbuilding to the main building for controlling light(s) at the outbuilding. Do not run the switch loop in the data conduit.

smithl3 · Mar 4, 2012

Thanks guys for the info.

Charles (in GA) · Mar 4, 2012

smithl3 said:
The exact wire I have is XLPE USE-2 UL aluminum three wire. Black insulated with one neutral wire with yellow stripe. A local electrician said I can ground locally to the garage with a ground rod and barn wire at the sub panel. As far as the breaker size, I had a 100 amp and planned on using it, if the wire I have isn't sufficient I can certainly downsize to a 75 amp, that would still be plenty for my needs in the garage.

As far as running the 14-3 wire in with this main power feed, am I correct in sayings can do it only if it is fed from the garage? If that is the case I don't see the logic, but code is code.

I have a separate conduit for data cables but I didn't want to put any power cables in there for the concern of messing with the data signals.

Not sure how to control my lights.... I definitely want then hard wired.

Thanks for all the info guys,
smithl3

Either you are on a much older code cycle than nearly everyone else, or your electrician is full of it. Four wire as a subfeed from a main panel to a subpanel has been the requirement for several code cycles now. I think you have to get back earlier than the 2005 code to find three wire with no ground OK for this installation.

The reason for not having current to a building from two or more sources is fairly simple and for safety purposes. You are planning to replace the light fixture or do some other work on the wires, fixture, etc. You have never seen this installation before (new owner, electrician called in to do work, etc) You pull the disconnect for the entire detached garage/shop, cannot be any safer than this? right? You unscrew some wire nuts and suddenly get hit with current!!!!!!!! You know you tripped the main, even tripped the subfeed breaker in the house panel that supplies the garage...... but its still HOT.... Its simply to keep people from getting electrocuted.

If I read the code correctly, if your USE wire is not rated any other way (unusual) then 338.12(B) forbids it from even entering the building, it must be spliced to an acceptable wire in a junction box before entering the building.

Charles

smithl3 · Mar 5, 2012

I see your point on tripping the sub panel breaker and still having one power line still hot. I will definitely change that around. The main #2 for a feed not being able to enter the house that is the first time I have heard of that. Is it the type of cable, or the aluminum or what that makes it not able to be run into the structure? It would pretty much come out of the ground, go into the house through an LB elbow and into the sub panel. Would that still not be allowed?

Thanks

pattenp · Mar 5, 2012

If the cable is rated just "USE" it has to stop outside of the building. The reason is the insulation on just straight "USE" is not fire rated. The wire would need the additional rating of "RHW" or "RHH" or "XHHW". The "USE" will need to stop in a junction box outside and be spliced to "SER" to continue into the house to the panel. You can use "SER" inside without conduit.

smithl3 said:
I see your point on tripping the sub panel breaker and still having one power line still hot. I will definitely change that around. The main #2 for a feed not being able to enter the house that is the first time I have heard of that. Is it the type of cable, or the aluminum or what that makes it not able to be run into the structure? It would pretty much come out of the ground, go into the house through an LB elbow and into the sub panel. Would that still not be allowed?

Thanks

Charles (in GA) · Mar 5, 2012

Examine the wire closely, with a light at different angles if the markings are difficult to read. It may very well have the RHH/RHW or other type markings on it. Difficult to believe that manufacturers would waste the time/money to make a single rated wire. For manufacturing and inventory purposes its cheaper and easier to make a multi-rated wire.

Code article 310 lists RHH and RHW as "conductors for general wiring" and RHW is suitable for wet locations. (underground, whether in a conduit or not, is considered wet location).

Charles

Charles (in GA) · Mar 5, 2012

338.12 Uses Not Permitted.
(A) Service-Entrance Cable. Service-entrance cable (SE) shall not be used under the following conditions or in the following locations:
(1) Where subject to physical damage unless protected in accordance with 230.50(B)
(2) Underground with or without a raceway
(3) For exterior branch circuits and feeder wiring unless the installation complies with the provisions of Part I of Article 225 and is supported in accordance with 334.30 or is used as messenger-supported wiring as permitted in Part II of Article 396

(B) Underground Service-Entrance Cable. Underground service-entrance cable (USE) shall not be used under the following conditions or in the following locations:
(1) For interior wiring
(2) For above ground installations except where USE cable emerges from the ground and is terminated in an enclosure at an outdoor location and the cable is protected in accordance with 300.5(D)
(3) As aerial cable unless it is a multi-conductor cable identified for use above ground and installed as messenger supported wiring in accordance with 225.10 and Part II of Article 396

Charles

smithl3 · Mar 6, 2012

Another thing I noticed was the conduit riser for the main power feed ended up between jack studs and a window once the framing went up yesterday. Window sizes changed to framed just changed.

Is it acceptable to jog the main power feed over one bay inside to get a full 16" opening for the sub panel, or should I dig up the conduit and re route it that way?

pattenp · Mar 6, 2012

The conduit needs to run all the way to the sub-panel, you can't just jog the wire from where the conduit enters the building. So the conduit needs to be jogged also. I wasn't sure if you were just asking about jogging the wire only.

smithl3 · Mar 7, 2012

I figured the power line had to be in the conduit the whole way, I just wasn't sure if it was only suppose to travel vertically directly to the panel or not. It may have to take a 90 degree turn horizontally for a bay to get to the panel.

I talked to my inspector today and he found a few kinks in my wiring plan.

I originally had 2-2-4 with a 6 copper ground with a 100 amp breaker to the sub panel. He said I need the neutral to be the same size as the conductors so I returned it to get 2-2-2-4 bundled together to feed the sub panel. He said the 100 amp breaker is fine for #2 Aluminum. I also asked about bringing the mobile home feed into the "interior" of the garage a few feet to the sub panel and he said it was no issue at all.

As far as the detached garage exterior lights goes he said I am perfectly fine powering it from the house.

Aceman · Mar 7, 2012

smithl3 said:
He said I need the neutral to be the same size as the conductors so I returned it to get 2-2-2-4 bundled together to feed the sub panel.

If you have any decent 240volt load in your garage, dropping a neutral size or two is usually not an issue. I do it all the time, and have never been questioned on it, not even once.

smithl3 said:
He said the 100 amp breaker is fine for #2 Aluminum.

The NEC says no, I wonder if you have a local amendment allowing it?

smithl3 said:
I also asked about bringing the mobile home feed into the "interior" of the garage a few feet to the sub panel and he said it was no issue at all.

It shouldn't be an issue if you're using mobile home feeder, it's multi rated RHH RHW, etc, the same stuff Charles posted about.

pattenp · Mar 7, 2012

Odd on having to up size the neutral. The mobile home feed also comes as 2-2-4-6. And as said #2 is only rated for branch circuit and feeders at 90A.

Indoor wire in conduit to detached garage

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