Rock knocker
Well-known member
- Joined
- Aug 14, 2014
- Messages
- 704
We don't even know if the 100A sub in garage 1 will accept a 100A breaker
Need help with wiring
- Thread starter Jacks Garage
- Start date
OP
Jacks Garage
Member
I will be running 5.5 HP air compressor, and small table saw, drill press, miter saw, etc. Just average homeowners tools, nothing big. Heater is a small propane portable unit. I will have about 6 or 8 four foot strip lights. Thanks for the help.
Alchymist
Well-known member
Doesn't matter - he's going to more than 6 circuits so the panel has to change anyway.
ez-duzit
Well-known member
From the OP's original post.
I take this to mean that each garage is to be capable of 100-amp service. My recommendations are based on this.
If a bunch of you are arguing that he can get away with a cheaper installation, where he has to turn everything off in one garage so he can run equipment in another garage, well, that is another story.
In my own garage, if my 7-1/2 hp air compressor comes on while I'm tig welding, my 100-amp panel is mostly maxed out, what with lights, etc. And I encourage the OP to not cheap out on the wiring. What will he save, 15' of wire?
I take this to mean that each garage is to be capable of 100-amp service. My recommendations are based on this.
If a bunch of you are arguing that he can get away with a cheaper installation, where he has to turn everything off in one garage so he can run equipment in another garage, well, that is another story.
In my own garage, if my 7-1/2 hp air compressor comes on while I'm tig welding, my 100-amp panel is mostly maxed out, what with lights, etc. And I encourage the OP to not cheap out on the wiring. What will he save, 15' of wire?
OP
Jacks Garage
Member
Well maybe I should feed off of the 200 amp house to run the 100 amp to the second garage. That way I wont have to replace anything in the first 100 amp garage. Would that be easier?
Coyote556
Well-known member
Is the meter at the pole or the residence? Where I am it is common to have the meter at the pole and use a triple tap meter base to feed up to three structures. It is done all over our county. Cuts out the whole issue of subpanels run from the house main panel. Then each structure is fed off one leg of the triple tap meter base.
pattenp
Well-known member
If now you're thinking the panel in the first garage would need to be changed, then yes it may be better to come off the main. Only you know how the feeder will need to be run from the main to get to the second garage.
ez-duzit
Well-known member
That is precisely the correct way to do this.
OP
Jacks Garage
Member
The meter is at the house. Reason I wanted to run off the 1st garage is because there is a lot of landscaping and sidewalk that I will have to dig around and under.
JohnX14
Well-known member
310.15 (B)(7)(2) allows for #4 Cu and #2 Al for the 100 amp installation described in the OP. There are a number of deviations allowed from Table 310.15(B)16. The 85 and 90 amps you cited are the general ratings of these conductors if no notes or correction factors apply.
wyliesdiesels
Well-known member
No that only applies when feeding the entire load of a dwelling. The OP is feeding a garage!
canbug
Well-known member
ez-duzit, your going to scare Jack to the point of not wiring his second garage. I have been an Electrician for 30 years and sub feeding from garage 1 to 2 will work fine. He isn't working in both garages at the same time and if the compressor in garage one starts up while he is in garage 2, the 100A isn't going to trip. Lets not overcomplicate this to death.
Tim.
Tim.
ez-duzit
Well-known member
To save 15' of wire?
wyliesdiesels
Well-known member
Dont woryy. Code enforcement officer C96 wil be along shortly to read ez-duzit his miranda rights and cuff him!
It does, the 100A breaker will trip if overloaded which I suspect will not be very likely.
You need to read the criteria that goes along with that table, then you will know that your giving really bad advice, BTW that table has been removed from the 2014 NEC.
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Dont woryy. Code enforcement officer C96 wil be along shortly to read ez-duzit his miranda rights and cuff him!
Yes, my bad, should have stepped in sooner.
ez-duzit needs a time out…
ez-duzit
Well-known member
If it can't be fixed with that hammer, it's an electrical problem. 
Lots of ways one can compromise the addition of 2 sub-panels to a main panel. 1 of them is to make one sub-panel a sub-panel of a sub-panel. If you all contend that code allows you to get away with such an installation, very well. But no one can rationalize it just to save 15' of wire. And thus creating a power management problem. And unnecessarily limiting future expansion.
Lots of ways one can compromise the addition of 2 sub-panels to a main panel. 1 of them is to make one sub-panel a sub-panel of a sub-panel. If you all contend that code allows you to get away with such an installation, very well. But no one can rationalize it just to save 15' of wire. And thus creating a power management problem. And unnecessarily limiting future expansion.
wyliesdiesels
Well-known member
If it can't be fixed with that hammer, it's an electrical problem.
Lots of ways one can compromise the addition of 2 sub-panels to a main panel. 1 of them is to make one sub-panel a sub-panel of a sub-panel. If you all contend that code allows you to get away with such an installation, very well. But no one can rationalize it just to save 15' of wire. And thus creating a power management problem. And unnecessarily limiting future expansion.
I take it that youve never been in a plant where sub panels are fed from subpanels all over the place because the MDP is too far to run homeruns for each subpanel!
ez-duzit
Well-known member
The main panel is nearby, in this case.