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Old 12-15-2011, 09:29 PM   #16
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New Sub Panel for Garage...


Most of the time THHN is dual rated as THWN also, but it must be marked on the wire to be used as such


Using #6 wire your neutral must be white, and your ground green. You're not allowed to remark black wire.

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Old 12-15-2011, 11:40 PM   #17
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The cable will be dual rated Thhn,Thwn and you must put it in pvc electrical conduit. The trench must be 18" to the top of the conduit,might want to rent a trencher .. walk behind or ride along. You will need 1 "conduit for 3 #6 awg and 1 #10 awg. If any of the conduit is exposed outside it will need to be sch. 80 the rest can be sch.40. When you come up out of the trench use a pvc sweep.

You need to have a means for a service rated disconnect at the garage panel. I don't see where your Murray panel has the capability for a backfed main breaker. Some jurisdictions will allow a rule called the 6 disconnect rule which simply means the buildings disconnect can be six throws on the hand and no more. So six single pole or double pole breakers or combination of them not exceeding six single throws to shut off all power. Any more than that and you must have a main breaker. The disconnect must be very near either inside or outside where you enter your garage with the underground feeder.


A Main breaker panel meets this requirement for a 'service rated' disconnect with a single throw of the hand.

You must separate neutral from ground in the garage panel. So your going to have to purchase a grounding bar for the murray panel. The one that came in the panel will be your neutral bar. The bonding means that is in that plastic bag will not be used.

It all will look like this (below) in the end ... the diagram shows a main breaker panel and your panel is main lug. See if the instructions mention a main breaker option but I don't think they will with that panel.
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Old 12-16-2011, 09:02 AM   #18
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The cable will be dual rated Thhn,Thwn and you must put it in pvc electrical conduit. The trench must be 18" to the top of the conduit,might want to rent a trencher .. walk behind or ride along. You will need 1 "conduit for 3 #6 awg and 1 #10 awg. If any of the conduit is exposed outside it will need to be sch. 80 the rest can be sch.40. When you come up out of the trench use a pvc sweep.

You need to have a means for a service rated disconnect at the garage panel. I don't see where your Murray panel has the capability for a backfed main breaker. Some jurisdictions will allow a rule called the 6 disconnect rule which simply means the buildings disconnect can be six throws on the hand and no more. So six single pole or double pole breakers or combination of them not exceeding six single throws to shut off all power. Any more than that and you must have a main breaker. The disconnect must be very near either inside or outside where you enter your garage with the underground feeder.


A Main breaker panel meets this requirement for a 'service rated' disconnect with a single throw of the hand.

You must separate neutral from ground in the garage panel. So your going to have to purchase a grounding bar for the murray panel. The one that came in the panel will be your neutral bar. The bonding means that is in that plastic bag will not be used.

It all will look like this (below) in the end ... the diagram shows a main breaker panel and your panel is main lug. See if the instructions mention a main breaker option but I don't think they will with that panel.

Stubbie, thanks for the help... Now Question... What exactly do you mean by this? "service rated disconnect at the garage panel. I don't see where your Murray panel has the capability for a backfed main breaker."

My garage has a full bath which came included when I purchased the house. The 1" conduit/grey pvc is a bit over 18" deep and runs from the house to the garage. I printed out the diagram that you posted, extremely useful, thanks a lot buddy.


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Old 12-16-2011, 11:40 AM   #19
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The NEC and most local codes require the detached garage have a disconnect to remove power from the garage. It is required to be service rated. This simply means that it must have a main bonding jumper capability (your murray panel has that) and be rated to serve as a service panel where the first means of disconnect is located. Yours won't be used as the service panel nor will you use the main bonding jumper that comes in that plastic bag. However the rating is required to serve as a building disconnect and yours will be and should say on the panel labeling that it can be used as service equipment.

The back fed main breaker is an option on some panels that allows you to install a main double pole breaker in two of the slots and backfeed it as a main disconnect for the panel. If yours will then I would suggest using that option so you have a one throw of the hand disconnect for the garage. A hold down kit will be required for that breaker to be code compliant. Again the panel labeling should make mention of this option.

You also need to look at the labeling to see where your gounding bars are to be located ... should be predrilled and swaged holes in the back of the panel where these are installed. You will install one, listed for your panel, and land all your bare or insulated grounds from your branch circuits along with the ground from the feeder from the house to the grounding bar. Your grounding electrode conductors that go out to your ground rod(s) will also land there.

Do not install the bonding strap that came in that plastic bag you do not need it.

It would be very wise to get the installation looked at by a qualified person or get a permit and have it inspected as this type work requires an inspection from the codes department in your county or city. Use good workmanship don't cut corners or be sloppy ..do it right...

Ask all the questions you want here on the forum and good luck with your project.
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Old 12-16-2011, 11:44 AM   #20
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*note to Stubbie* Thanks for that diagram.
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Old 12-16-2011, 11:56 AM   #21
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Yeah, first thing I was going to say - the panel the OP shows does not have a main breaker, and he needs that. If you get a panel that's a main lug, it doesn't have a main breaker on it and you can't use it for a sub-panel that is remotely located from the panel to which it is connected.

A main lug can be used if you need to ad a sub panel next to your main panel because you are running out of space in the main panel. (as an example) but if you had to shut off the whole panel and you were in the garage, you'd have to go into the house.

That's my understanding of it basicly as a lay person, and I went through this project myself as well so if you want to look through my post history from this past summer you might learn a lot about the project as well.
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Old 12-16-2011, 01:35 PM   #22
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*note to Stubbie* Thanks for that diagram.
Your welcome
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Old 12-16-2011, 01:52 PM   #23
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Yeah, first thing I was going to say - the panel the OP shows does not have a main breaker, and he needs that. If you get a panel that's a main lug, it doesn't have a main breaker on it and you can't use it for a sub-panel that is remotely located from the panel to which it is connected.

A main lug can be used if you need to ad a sub panel next to your main panel because you are running out of space in the main panel. (as an example) but if you had to shut off the whole panel and you were in the garage, you'd have to go into the house.

That's my understanding of it basicly as a lay person, and I went through this project myself as well so if you want to look through my post history from this past summer you might learn a lot about the project as well.
The key for residential garages being served by one electrical system, usually 3 wire single phase 120/240, is whether they are 'attached' or 'detached' to the dwelling with the service equipment. The building or dwelling or structure that contains the 'service equipment' must have a single disconnect whether 6 handle rule or main breaker that removes power from all areas in the building. So if the added panel is in the same structure as the service equipment it is not required to have a main disconnect and an mlo panel is fine. The service equipment is your disconnect in this case.

If the garage is detached and receives its power source from the service equipment in the dwelling and even though turning off the main in the service equipment panel will also kill the power to the detached garage the NEC requires that a disconnect be established for the garage.

4 wire feeders are now required for detached buildings so any 3 wire feeders must be existing.

As I mentioned many jurisdictions do not require a main breaker disconnect or single throw disconnect in a separate enclosure from a panel. They will allow the 6 disconnect rule though IMO they are not applying current code correctly none the less I don't lose any sleep over it but I do prefer a single throw disconnect.
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Old 07-05-2012, 09:54 PM   #24
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hey guys, just wanted to let you know that everything turned out GREAT!!! I will post pics by tomorrow.
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Old 07-06-2012, 09:12 PM   #25
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Post deleted wrong thread.


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