100 amp sub panel

[BobMeyer58]

I need to run wire for a 100 amp sub panel to a detached shop. It will run about 50 feet in the attic of my house to the back yard. Then down to be under ground 25 feet to the sub panel on the shop. What wire do I need for both? Is there a 2-2-2-4 copper or do I need 4 seperate wires?

 

[Chuckster in NJ]

I need to run wire for a 100 amp sub panel to a detached shop. It will run about 50 feet in the attic of my house to the back yard. Then down to be under ground 25 feet to the sub panel on the shop. What wire do I need for both? Is there a 2-2-2-4 copper or do I need 4 seperate wires?

Look this up in the NEC……. "IF" you are asking a question like this, it is proof that you are not qualified so call a professional.

 

[manwithtools]

Not a very nice way to respond to a new (since 2013) member with a single question about his electrical install. I'll agree it's a bit vague, but maybe with a little more information we can help hm select the right solution for his feed to his shop.

OP, tell us more about what you have going on in your shop / project.

 

[My Old Tools]

If you put your subpanel on a 90 amp breaker, you can run AL 2-2-2-4 mobile home feeder wire. Now all the experts can come tell you why you can't. Will you require a permit and inspection?

 

[Chuckster in NJ]

Not a very nice way to respond to a new (since 2013) member with a single question about his electrical install. I'll agree it's a bit vague, but maybe with a little more information we can help hm select the right solution for his feed to his shop.

OP, tell us more about what you have going on in your shop / project.

"IF" you were an electrical contractor who served an apprenticeship, obtained his license and now pays insurance you would understand why I don’t tell anyone how to do an electrical job like this over the internet.……. Nobody sees what materials are being used, the job site conditions or his knowledge of electric.

BTW! As an electrical inspector I have seen (and failed) many "homeowner Joe jobs" where the owner spent hours searching the internet for how to advice.…… I have also seen some really bad electrical jobs performed without an inspection that caused a fire or a new homeowner who inherited the electrical nightmare on a foreclosure.

 

[u2slow]

Dont know where you are located, but in my jurisdiction we run ACWU cable end-to-end. #2 for 90A.

 

[zimman]

Not a very nice way to respond to a new (since 2013) member with a single question about his electrical install. I'll agree it's a bit vague, but maybe with a little more information we can help hm select the right solution for his feed to his shop.

OP, tell us more about what you have going on in your shop / project.

Some days around here are like Facebook, but shittier. LOL
I've been a Mod before on some other forums and it ceases to amaze me why folks just don't scroll on by.
Zim

 

[cpakalolo]

I need to run wire for a 100 amp sub panel to a detached shop. It will run about 50 feet in the attic of my house to the back yard. Then down to be under ground 25 feet to the sub panel on the shop. What wire do I need for both? Is there a 2-2-2-4 copper or do I need 4 seperate wires?

Yes, your wire will come as four in one. Usually. Some SE will come wrapped as an assembly for direct burial. Put in some PVC conduit of your choosing and go. Just general info. The ground is usually one size smaller and sometimes the neutral is smaller, but I don't like to shrink the neutral. In your sub panel, the neutrals and grounds are kept separate. You still need a good ground rod attached to your subpanel. Use the ampacity tables and use 75 degrees for the specific type of wire written on the wire's jacket. The tables are per 100 feet so, at 75-80 feet you can use the numbers as you see them without length deration.

 

[wyliesdiesels]

make sure whatever cable type you use its rated for underground use. conduit wont change that rating for a cable that isnt rated properly

 

[75gmck25]

AFAIK, most SER is not rated for direct burial or running underground in conduit. When you need direct burial or burial in conduit you must transition to Mobile Home Feeder (MHF) or other cable that is rated for underground use.

Many folks use 2-2-2-4 AL MHF, which is rated for direct burial, but must be in conduit inside a dwelling, and it can handle 90 amps. Just use a 90 amp breaker in the main panel and don't worry about the 100 amp breaker on the sub-panel (its now just a disconnect).

 

[dcg9381]

Look this up in the NEC……. "IF" you are asking a question like this, it is proof that you are not qualified so call a professional.

I've asked all sorts of dumb questions here. Shame me if you want.

Better to point out I'm doing it wrong and point me to NEC so I learn something. Which has happened to me many times.

Part of the "joy" of this forum is that there are a lot of credential-educated professionals that will give their non-binding, unofficially licensed options about how THEY would do something, subject to your local rules and regs.. You get what you're paying for.

"IF" you were an electrical contractor who served an apprenticeship, obtained his license and now pays insurance you would understand why I don’t tell anyone how to do an electrical job like this over the internet

...Then qualify your answers.. Or (politely) go to a forum where non-sparkies can't ask questions, because those exist.
Everyone on GJ knows then answer is 90A MHF that has to be in conduit once it reaches the dwelling.

2" conduit is what I run, works fine for 90A MHF 2-2-2-4 feeder. Too rocky here to run direct burial.

 

[theoldwizard1]

If you put your subpanel on a 90 amp breaker, you can run AL 2-2-2-4 mobile home feeder wire.

MHF requires conduit inside of a building.