Minimum requirement for detached garage.

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frizbeedog

Senior Member
Location
Oregon
bth0mas20 said:
Thanks for all of your responses.

The install that ive decided on:

Single 30a circuit out of the house panel. Then 60ft of 10-2 uf underground to the detached garage. Up the side of the garage sleeved in pvc thru the wall to a 4 space panel (only 120v no 240v). No grounding electrode. One circuit fed by a 15a arc fault bkr for 4 medium base lights total. Then a 20a breaker to a GFCI protected outlet circuit with 4 outlets.

I probally put more info than was needed to explain this. I feel that this will be sufficient to pass code.

Why an arc fault?
 

iwire

Moderator
Staff member
Location
Massachusetts
bth0mas20 said:
I only plan to install 2 bkrs in the panel. Less than 6 throws. Why would I need a ground rod or two.

You need a grounding electrode system because you are running a feeder there.

250.32(A)

And as far as the 'less then 3 throws of the hand' bit, it is really tough to accomplish legally in a detached structure, better off using a main breaker panel.
 

frizbeedog

Senior Member
Location
Oregon
iwire said:
You need a grounding electrode system because you are running a feeder there.

250.32(A)

And as far as the 'less then 3 throws of the hand' bit, it is really tough to accomplish legally in a detached structure, better off using a main breaker panel.

And Bob will get you back on track. Hang in there. :smile:
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
If you are only running 2 circuits then run a 10/3 uf w/ground and use a wp pullout at the garage. No electrode no breakers.
 

bth0mas20

Senior Member
Location
Maryland
Thanks.
I just looked at the book and it just says arc faults for dwelling units.
Also It dosent look like I need to use tamper proof outlets either.
 

frizbeedog

Senior Member
Location
Oregon
bth0mas20 said:
I only plan to install 2 bkrs in the panel. Less than 6 throws. Why would I need a ground rod or two.

Dive into Article 225 and spend some time there. It will be worth it.

After that, separate structures like garages will be a snap. :smile:
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
roger3829 said:
Not sure about 3/4" being good for 100a.

How did you calculate that?

I get about 50a:-?
My bad, you're right. 100a would require a 1" PVC run; the 3/4" would be good for up to 60a.
 

tryinghard

Senior Member
Location
California
frizbeedog said:
Just to be clear. A Grounding electrode is not required for a single circuit. See the exception to 250.32. This inculudes a MWBC.

Also see Art 225 Outside branch circuits and feeders

Edit....Had I continued to read the thread I would have known they already said that.

Yep and so did I (ahead of "they") in Post #15, but thanks for your attention to this topic :)
 

tryinghard

Senior Member
Location
California
bth0mas20 said:
I can run a 12/3 uf to a wp 30a disc outside then to the two seperate circuits. One for lighting and one for outlets right.

Yes you can without an electrode at the 2nd building.

Sounds like the customer really wants "bare bones"; in this light I suggest giving them one circuit, exclude trench, backfill, and include NM only in structure also exclude metallic conduit and armored cable thay will need to cover the NM with something not you.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
bth0mas20 said:
I only plan to install 2 bkrs in the panel. Less than 6 throws. Why would I need a ground rod or two.
Because you now have a feeder serving the building and not a branch circuit. The grounding electrode exception only applies when the second building is served by a branch circuit.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
don_resqcapt19 said:
Because you now have a feeder serving the building and not a branch circuit. The grounding electrode exception only applies when the second building is served by a branch circuit.
The way I look at it is pretty much if you put a panel board in the separate structure or run more than one circuit to it, it needs a GES.
 

bth0mas20

Senior Member
Location
Maryland
tryinghard said:
Yep and so did I (ahead of "they") in Post #15, but thanks for your attention to this topic :)


Thanks for your comment. You really set me straight on that one.
I was just making sure because I just wasnt 100% sure of what was right. Sorry If it bothered you.
 

tryinghard

Senior Member
Location
California
bth0mas20 said:
Thanks for your comment. You really set me straight on that one.
I was just making sure because I just wasnt 100% sure of what was right. Sorry If it bothered you.

No apology necessary, my reply was to frisbeedog's post #18. I like this stuff :grin:
 
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