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Old 07-03-2008, 10:58 AM   #1
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Enhancing existing wiring to detached garage


I have a detached garage that receives power off our main house breaker panel via a single dedicated breaker. Our panel is not grounded. The single hot wire runs under the house, into the ground and then into the garage.

In the garage I have 2 outlets and one switched light. I've set up a few overhead fluorescent lights in there, which just plugin, but I'd like to hook them up properly with a switch. I also want to add a few more overhead fluorescents.

That would bring the total number of fluorescent housings (2 40 watt bulbs per housing) to 5, not to mention the two outlets (which rarely have anything plugged in, save for a battery charger or a 40W shop light).

I thought I could install a subpanel in the shop with a couple breakers, is this a good idea or is it pointless?

I'm not sure what the breaker that feeds the shop is rated it, I guess that's probably priority number one.

It's an old house and I'm trying to make do with what I have for the time being until we have enough money to have the house rewired and a new panel installed.

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Old 07-03-2008, 12:23 PM   #2
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Enhancing existing wiring to detached garage


A sub panel is an excellent idea. How big is your garage?
Counting the breaker that feeds the garage do you have another spare? You will need 2 empty slots for a two pole breaker. This breaker will feed a four wire circuit to the garage. You will need 2 hots, 1 neutral and 1 ground. You can use conduit or direct burial cable (UF).
You will need to dig a trench for this feeder as the cable you now have has only 3 wires in it. So it must be replaced.
Then you will need a sub panel with a main breaker. You will choose the size you need. I would recommend no less than 30 amp. But you can go higher.
Run the 4 wire cable from your main service panel to the sub panel in the garage. Then let us know and we will tell you how to connect the wires and go over anything you may not be sure about. In the meantime let us know how you are doing with the first part of this project.

Someone here will give you the burial depth for UF cable or conduit.

PS.....This subject has been discussed here at length more times than I can count. Just as recently as this week. I think the thread is still somewhat active so scroll through the last couple of days and you may find all your answers in the previous thread.

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Last edited by J. V.; 07-03-2008 at 12:35 PM.
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Old 07-03-2008, 02:45 PM   #3
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Enhancing existing wiring to detached garage


for a detatched garage, by code you can only put in a minimum 60 amp panel. You would have to establish a new ground by driving ground rods. You would need to trench out there, install some pvc, and pull in the wire.

If you want to ignore code and pretend its an atatched garage. you can either match the breaker in your current panel to your new main breaker, or dig a trench, put in some pvc, and put in whatever size wire you want
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Old 07-03-2008, 03:00 PM   #4
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Enhancing existing wiring to detached garage


My existing wire is already run underground through PVC, but it sounds like the recommendation is to run new wire out there, hopefully I can use my existing PVC.
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Old 07-03-2008, 03:15 PM   #5
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Enhancing existing wiring to detached garage


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Originally Posted by jimmy21 View Post
for a detatched garage, by code you can only put in a minimum 60 amp panel.
Can you tell me where you got that info from? Never heard of that but, I suppose anything is possible.
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Old 07-03-2008, 03:21 PM   #6
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Enhancing existing wiring to detached garage


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Originally Posted by jimmy21 View Post
for a detatched garage, by code you can only put in a minimum 60 amp panel. You would have to establish a new ground by driving ground rods. You would need to trench out there, install some pvc, and pull in the wire.
THis is not true, the DISCONNECT needs to be rated at 60 amps, not the panel.

Section 225.39 (D)

In other words, you can easily run #12 feeder to the garage, but your disconnect would have to be rated at 60 amps.

Last edited by chris75; 07-03-2008 at 03:33 PM.
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Old 07-03-2008, 03:42 PM   #7
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Enhancing existing wiring to detached garage


oops, double post

Last edited by jimmy21; 07-03-2008 at 03:44 PM.
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Old 07-03-2008, 03:43 PM   #8
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Enhancing existing wiring to detached garage


Quote:
Originally Posted by chris75 View Post
THis is not true, the DISCONNECT needs to be rated at 60 amps, not the panel.

Section 225.39 (D)
Quote:
Originally Posted by wirenut1110 View Post
Can you tell me where you got that info from? Never heard of that but, I suppose anything is possible.
services: size and rating
230.79(D): For all other installations, [not including: single family dwellings(100A)or 1 or 2 circuit installations] the service disconnecting means shall have a rating of not less than 60 amperes

And i can't remember where youd find the other atricle. But there is another article that says you can only take 2 (or 3, i can't remember) circuits to a seperate building. Like a pump house you can take a circuit for the pump, and one for the lights and a receptacle

So, therefor, if its a detatched garage (a seperate building), you must establish a new service (minimum 60A). if its part of the house on the other hand, you dont need to establish a new service, and you can just run whatever you want
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Old 07-03-2008, 03:44 PM   #9
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Enhancing existing wiring to detached garage


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Originally Posted by jimmy21 View Post


services: size and rating
230.79(D): For all other installations, [not including: single family dwellings(100A)or 1 or 2 circuit installations] the service disconnecting means shall have a rating of not less than 60 amperes
Your in the wrong section, a detached structure would fall under 225, not 230.
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Old 07-03-2008, 03:49 PM   #10
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Enhancing existing wiring to detached garage


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Originally Posted by jimmy21 View Post

And i can't remember where youd find the other atricle. But there is another article that says you can only take 2 (or 3, i can't remember) circuits to a seperate building.
You need to read 225.30, your only allowed one feeder or branch circuit, unless it falls under 225.30 (A) - (E)


Quote:
Originally Posted by jimmy21 View Post
So, therefor, if its a detatched garage (a seperate building), you must establish a new service (minimum 60A). if its part of the house on the other hand, you dont need to establish a new service, and you can just run whatever you want
Its not a service, not sure why you keep calling it that. And it does not need to be 60A, only the required disconnect rating.

Last edited by chris75; 07-03-2008 at 03:53 PM.
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Old 07-03-2008, 03:50 PM   #11
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Enhancing existing wiring to detached garage


no, it would be a new service, not a branch circuit. If you ran circuits out there you can run whatever your load is. But if you put a panel in, it has to be a new service if its a seperate building

i posted that one before your second post came up. I see what your saying. I looked up the definition of a service, and it agrees with you. I'll see if anyone at work can clear this one up

but...... the way im describing it is the way its enforced here. That is, if you want more than 2 circuits, you must install a sub panel, drive ground rods, and it has to be a minimum 60A

Last edited by jimmy21; 07-03-2008 at 03:56 PM.
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Old 07-03-2008, 03:55 PM   #12
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Enhancing existing wiring to detached garage


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Originally Posted by jimmy21 View Post
no, it would be a new service, not a branch circuit. If you ran circuits out there you can run whatever your load is. But if you put a panel in, it has to be a new service if its a seperate building

You cant run circuits out to a garage, only one branch circuit, or one feeder.

and its not a new service. its a panel being supplied from the load side of the service disconnecting means...


Not poking fun, but you really need to refresh your memory about section 225.

Last edited by chris75; 07-03-2008 at 03:58 PM.
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Old 07-03-2008, 04:08 PM   #13
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Enhancing existing wiring to detached garage


it is 225.39. And i think your in temperating it wrong. The disconnect feeding the garage would need to be 60A. Not the main in the sub panel
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Old 07-03-2008, 04:13 PM   #14
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Enhancing existing wiring to detached garage


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Originally Posted by chris75 View Post
You cant run circuits out to a garage, only one branch circuit, or one feeder.

and its not a new service. its a panel being supplied from the load side of the service disconnecting means...


Not poking fun, but you really need to refresh your memory about section 225.

maybe our terminology differs here (in Oregon) from wherever you are. But what i'm referring to as a new service is at the point where you establish a new ground. Maybe that doesn't agree with the code books definition of a service

and again, thats the way its enforced here
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Old 07-03-2008, 04:15 PM   #15
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Enhancing existing wiring to detached garage


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Originally Posted by jimmy21 View Post
it is 225.39. And i think your in temperating it wrong. The disconnect feeding the garage would need to be 60A. Not the main in the sub panel

[edited]

No where are you required to run a 60 amp feeder to a seperate structure.


Hope that clears it up for you. We've already run this thread a muck, PM me if you have any doubts on this install and we can start from scratch.

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Last edited by chris75; 07-03-2008 at 04:20 PM.
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