Sizing wire to detached garage

[slipshodcavalier]

Hi all,

I'm running power to a detached garage, and wanted to make sure I'm not missing anything.

The garage will have a 100 A subpanel and 4 circuits:

Circuit 1 (Lights)
80' 14 AWG on 15 A breaker
2.3 A continuous load, 0 A non-continuous

Circuit 2 (Garage door opener)
40' 14 AWG on 15 A breaker
0 A continuous load, 5 A non-continuous

Circuit 3 (Receptacles)
55' 12 AWG on 20 A breaker
2.5 A continuous load, 15 A non-continuous

Circuit 4 (Heater)
40' 8 AWG on 40 A breaker
31.2 A continuous load, 0 A non-continuous

Since the load totals are 36 continuous and 20 non-continuous, I was going to use a 60 A breaker in the main panel with 6/3 UF-B. However, I'm not sure about the voltage drop--in addition to the branch lengths above, the feeder is 90' from the main panel to the sub panel. Would I need to upgrade to 4 AWG THWN in conduit? If so, would the breaker also get up-sized?

 

[anuccite]

If you are putting a 100amp panel in there.... Might as well run 2-2-2-4 MHF in conduit if you have to dig the yard anyway.... 90Amp breaker on in the main panel

 

[wyliesdiesels]

agree with above. #2 al MHF is a better choice and will save you some dough

dont forget 2 ground rods spaced 6' and an isolated neutral bar which may mean purchasing a separate ground bar kit.

 

[slipshodcavalier]

Thanks. Don't know much about MHF. Can you direct bury? Does it need conduit indoors?

 

[wyliesdiesels]

Thanks. Don't know much about MHF. Can you direct bury? Does it need conduit indoors?

It can be direct buried but conduit is highly recommended.

It does need to be in conduit indoors since its individual conductors.

If conduit indoors is an issue, you can transition to SER for the indoor portion of the run.

 

[75gmck25]

If you are going to also run it in conduit indoors, make sure it is dual rated for inside (RHH / RHW) and direct bury outside (USE-2).

It will be similar to this cable. https://www.wireandcableyourway.com/2-2-2-4-aluminum-mobile-home-feeder-cable.html

Bruce