Adding a breaker panel to a detached building 80 feet from main panel

[honda1998civic]

Adding a breaker panel to a detached building/mancave 80 feet from main panel. I’m wanting to add a stove, ac window unit, small plug in heater, and lighting.

So my recommendations were to add 100 amp panel at the detached building and run #2 wire and ground to panel. I’ll be using two 20 amp circuits. And one 50 amp circuit to stove. Is any of this over kill? Do I need #2 wire or is it over kill since I’ll be running it atleast 80 feet. If I can reduce size it would be more cost effective.

Please add comments.

 

[sberry]

Number 2 alum Wire is super effecient for this. The distance is not an issue.

 

[pattenp]

The #2 Al can give you up to 90A, not 100A if that's what you think. Unless you're thinking #2 copper which is good for up to 115A.

 

[wyliesdiesels]

use #2 al MHF. you will need 2 ground rods at the detached building and an isolated neutral bar in the subpanel.

2" conduit would be ideal but 1 1/4" is the smallest you can use

 

[honda1998civic]

Ok. Another question. If I have room in my main panel and going to run three circuits. Can I just add to main panel? Would the only reason to add a subpanel be if you are out of room in main panel? So fill up main panel slots first then worry about a subpanel?

 

[pattenp]

Are you asking about running three circuits to the detached building vs. one feed to a subpanel in the detached building? If so, NEC only allows for one power feed to a detached structure, so three circuits to the detached building is not allowed. I assume you're still talking about the detached building?

 

[honda1998civic]

Yes I was. Thanks for clarification.

Also is there certain brand breaker panels preferred whether it’s expense, or reliability in breakers?

 

[pattenp]

Better panels are Eaton CH and Square-D QO. Cheaper are Eaton BR and Square-D Homeline. You may want to match the panel to the same brand in your home unless you have a crappy brand panel in the house. Of the two cheaper I mentioned I'd go with the Square-D Homeline.

 

[honda1998civic]

Ok. Cool. I’m showing I have square-d QO on both panels. Would aluminum or copper buss bar make your decision up? Of course the copper is a little more costs. But has this ever been an inssue?

 

[75gmck25]

This is a common question, so there is a relatively standard solution that many have used. I may have missed a couple items, but I'm sure there will be other comments.
- Square D QO 100 amp, 24 space panel (very easy to find, matches your QO)
- 60 to 90 amp (max) breaker for main panel; 60 amp available at home store, 90 from electrical supplier
- Isolated ground bar for sub panel
- Two 8 foot ground rods for sub panel
- Roll of #6 (IIRC) gauge bare copper ground wire, and clamps for rods
- 2-2-2-4 dual rated AL MHF to go from panel to panel
- Conduit (2" preferred) to protect wire when above ground
- Conduit for wiring when running inside a structure (required with MHF inside)
- Conduit for underground protection at 18"; if you bury at 24" MHF can be direct bury

You can buy all of these items at nearly any big box home store, or get them from an electrical supply house. You are also going to need to rent or borrow a trencher, and will need various junctions, LBs, bushings, and other parts to properly install the conduit.

Bruce

 

[mike93lx]

Ok. Cool. I’m showing I have square-d QO on both panels. Would aluminum or copper buss bar make your decision up? Of course the copper is a little more costs. But has this ever been an inssue?

Both work just fine.

 

[alfredeneuman]

- Isolated ground bar for sub panel

A little correction:
An un-isolated ground bar. The ground bar should be directly connected to the panel's inside metal.

(EDIT) A standard roll of #6bare ground wire is 315' which is way too much. It's available by the foot.

 

[wyliesdiesels]

This is a common question, so there is a relatively standard solution that many have used. I may have missed a couple items, but I'm sure there will be other comments.
- Square D QO 100 amp, 24 space panel (very easy to find, matches your QO)
- 60 to 90 amp (max) breaker for main panel; 60 amp available at home store, 90 from electrical supplier
- Isolated NEUTRAL bar for sub panel
- Two 8 foot ground rods for sub panel
- Roll of #6 (IIRC) gauge bare copper ground wire, and clamps for rods
- 2-2-2-4 dual rated AL MHF to go from panel to panel
- Conduit (2" preferred) to protect wire when above ground
- Conduit for wiring when running inside a structure (required with MHF inside)
- Conduit for underground protection at 18"; if you bury at 24" MHF can be direct bury

You can buy all of these items at nearly any big box home store, or get them from an electrical supply house. You are also going to need to rent or borrow a trencher, and will need various junctions, LBs, bushings, and other parts to properly install the conduit.

Bruce

Fixed it for ya