Upgrading panel to detached garage

[tec508]

2-2-2-4 AL is rated at 90 amps, and readily available at a good price in either MHF or SER. Do you really need that additional 10 amps? You can use a 100 amp sub-panel and a 90 amp breaker in the main panel.

I ran 2-2-2-4 AL SER inside the house and then transitioned to 2-2-2-4 AL MHF and buried conduit for the run to the garage. I had to use a large junction box and some relatively expensive wire connectors (Polaris?) to make the connections, but other than that it was relatively simple.

Bruce

I thought you had 2" pipe? You could pull 4/0 through pipe that size if you needed to, 2/0 or less will fit easily. Need #1 Al for 100a. That will fly into 2 inch pipe.

I've just been steering away from AL due to the extra work it's going to take. My conduit doesn't go all the way from box to box just building to building so I'll have to do a j-box and transition to a different cable at both ends.

I don't necessarily "need" the extra 10 amps, but I can see my shop getting close to 90A easily even exceeding it under rare circumstances.

It's all hobbies and fun stuff but I will have some occasional high current demands:

- 35-50A Welders
- 40A CNC Plasma cutter
- 40A lift
- 30A A/C
- 20A Air compressor
- Misc. Power tools / Chargers / Shop tunes / Etc..
- Lights

Now I know I won't be using all of these things at once, but it's reasonable to assume I'd have the plasma table cutting, the air compressor running, and the Tstat call for cooling.

With lights and other stuff going that could easily put me over 100A. I don't see that all the time, but I certainly could see the benefit of the additional 10A when the labor to do it is the same and the cost is nominal. Re-doing it later wouldn't be ideal.

6/3 NM-B is what's there now. I was going to replace it with 2/3 NM-B but that stuff is $6-7/ft!

 

[tec508]

Another thought-

What if I add to my conduit so it makes it to both panels (not just to the buildings). Could I do 100A over individual AL conductors XLP/USE-2/RHH/RHW-2?

1-1-1-2?

 

[alfredeneuman]

6/3 NM-B is what's there now. I was going to replace it with 2/3 NM-B but that stuff is $6-7/ft!

NM is against the Code for all outdoor use, let alone underground.

 

[tec508]

NM is against the Code for all outdoor use, let alone underground.

I know. The best part is that's what the electrician pulled before I bought the house, and that's what passed inspection. During my research for something cheaper I realized NM-B wasn't the right thing anyway.

Gotta love how code enforcement is really a matter of interpretation.

 

[NUTTSGT]

I've just been steering away from AL due to the extra work it's going to take. My conduit doesn't go all the way from box to box just building to building so I'll have to do a j-box and transition to a different cable at both ends.

I don't necessarily "need" the extra 10 amps, but I can see my shop getting close to 90A easily even exceeding it under rare circumstances.

It's all hobbies and fun stuff but I will have some occasional high current demands:

- 35-50A Welders
- 40A CNC Plasma cutter
- 40A lift
- 30A A/C
- 20A Air compressor
- Misc. Power tools / Chargers / Shop tunes / Etc..
- Lights

Now I know I won't be using all of these things at once, but it's reasonable to assume I'd have the plasma table cutting, the air compressor running, and the Tstat call for cooling.

With lights and other stuff going that could easily put me over 100A. I don't see that all the time, but I certainly could see the benefit of the additional 10A when the labor to do it is the same and the cost is nominal. Re-doing it later wouldn't be ideal.

6/3 NM-B is what's there now. I was going to replace it with 2/3 NM-B but that stuff is $6-7/ft!

If you think you might be pushing it, have you considered a separate service for the shop ? A simple phone call or email to your local PoCo might answer some cost questions and they may run everything to a new meter base.

 

[wyliesdiesels]

I know. The best part is that's what the electrician pulled before I bought the house, and that's what passed inspection. During my research for something cheaper I realized NM-B wasn't the right thing anyway.

Gotta love how code enforcement is really a matter of interpretation.

Some code is definitely up for interpretation.

However nm-b not being permitted for use outdoors or underground is pretty clear and theres nothing to interpret.

Im guessing the electrician didnt give a squat and the inspector was too busy to inspect everything...

 

[AntonLargiader]

I think you plan to replace it, but I want to clarify that it's not just a code issue. NM-b WILL self-destruct when it soaks through. You need to replace it as a matter of function and safety, not just compliance.