Detached garage wiring question - 2-2-2-4 MHF

[snowdust2]

I just finished running 2-2-2-4 MHF 200' total from house to shop. House has a 200a main panel and a 100a sub panel when they finished the basement. I tied into the 100a subpanel with the MHF wire for now to a 50a breaker I already had. On the shop side I have a 100a panel found here: https://www.menards.com/main/electr...e-pk/qo124m100pcvp/p-1444444027693-c-6437.htm

I now know the 100a is too high for that wire at that length. I'm trying to figure out what my options are now. I haven't hooked up the shop side yet and could change out the panel if I had to. Maybe I can just change out the main breaker in that panel to a 80 or 90 amp and then do the same amp breaker on the house side? (not sure if you can change out main breakers in boxes) I know to do the two ground rods and keep neutral and ground separate in the box with the added ground bars I already purchased. Everything is in conduit as well. Thanks!

 

[snowdust2]

Maybe change the garage main breaker to this 80a? https://www.pacificcoastbreaker.com...5TDOy9cR2zepSNFL01Q31y_sK68N0QMRoC-hgQAvD_BwE

 

[mike93lx]

The main in the garage doesn't matter at all, it is just a means of disconnect. You could put a 200a out there

The breaker in the house is what matters and can't be above 90a,although you shouldn't try to draw even that much due to voltage drop.

You are fine to leave it as is

 

[Norcal]

To my knowledge they don’t even make a breaker smaller then 100A for those mains, they are not the same as a plug-in QO or HOM breaker, that being said, there is no need to replace it as it is just a disconnect, proper overcurrent protection is being provided at the source. Only way to match them would be to buy a main lug panel & back feed a breaker with the required hold down kit in the panel, no need to do so and the original plan is more cost effective.

Keep
It
Simple
Sir

 

[snowdust2]

Great news! I'll get an 80a for the main and call it a day. Thanks guys!!

 

[pattenp]

I assume you are changing the 50A to an 80A in the house panel. Saying you're going to get an 80A for the main is a little confusing.

 

[snowdust2]

Sorry. Yes 80a at the house panel. No changes at the shop.

 

[sberry]

Get a 60 for the house. Bought 10$. It's right for that v drop at that distance anyway. I was hopine for a 60, just gave up 48$ for a 90 the other day where 60 would have done just as well..

 

[mike93lx]

Get a 60 for the house. Bought 10$. It's right for that v drop at that distance anyway. I was hopine for a 60, just gave up 48$ for a 90 the other day where 60 would have done just as well..

I found out this weekend that buying a 60 doesn't always work. Siemens 2 pole 60 won't accept #2. Was annoying, particularly because no one stocks bigger around me and there is a sharp price jump after 60

 

[sberry]

That would be a problem. As I said I just bought a 90 for a garage could make it easy on 60 . I might pocket it for a service call where I could get my money back.
My benchmark for garage is 60A. My bud had a real 5 comp in a garage he worked 30 yrs in
On a 60 breaker we hooked to a 2 about 150 ft maybe. His comp didn't leak and in/around a garage like that ya ain't got to arc up a 50A welder if someone is using air anyway. Never a trip, not 1 ever.

 

[spudley]

I found out this weekend that buying a 60 doesn't always work. Siemens 2 pole 60 won't accept #2. Was annoying, particularly because no one stocks bigger around me and there is a sharp price jump after 60

I'm using a 60 amp Homeline breaker with the 2-2-2-4 AL MHF. Might be presumptuous but I'd think a QO 60 amp breaker would also accept a #2.

I'm only running about 80' so I'll put in the 90 amp brkr when my wife buys me a Tesla.

 

[mike93lx]

I'm using a 60 amp Homeline breaker with the 2-2-2-4 AL MHF. Might be presumptuous but I'd think a QO 60 amp breaker would also accept a #2.

I'm only running about 80' so I'll put in the 90 amp brkr when my wife buys me a Tesla.

Square d 60's do accept #2. Saw those at Lowe's thisbwrekend

 

[wyliesdiesels]

I'm using a 60 amp Homeline breaker with the 2-2-2-4 AL MHF. Might be presumptuous but I'd think a QO 60 amp breaker would also accept a #2.

I'm only running about 80' so I'll put in the 90 amp brkr when my wife buys me a Tesla.

Is your main a sq d homeline?

 

[spudley]

Is your main a sq d homeline?

Yes sir, as is my sub.
BTW, I followed your wiring tutorial (sticky) to a "T".
You've been a great resource.
Thank you.

 

[JCU]

2-2-2-4 you have to use the 75c column in 310 then you can go up to the next size standard breaker 90amps. I just did it with 5 panels in 4 buildings. You can still use the 100a breakers in the panel but they have to be fed with 90a from the main panels.

 

[alfredeneuman]

2-2-2-4 you have to use the 75c column in 310 then you can go up to the next size standard breaker 90amps.

The ampacity of #2Al @ 75C is 90amps