100 Amp Service

[s1nemesis1s]

Hello all,

I am looking to run 1.5 conduit underground 100 feet to my garage. I want 100 amps of electrical service - 2-2-2-4 wire URD or should I look at copper? WOuld copper 4-4-4-6 support it?

I am not worried about code because I am away from all that - but I don't want to burn my house down.

 

[Megawatt]

Hello all,

I am looking to run 1.5 conduit underground 100 feet to my garage. I want 100 amps of electrical service - 2-2-2-4 wire URD or should I look at copper? WOuld copper 4-4-4-6 support it?

I am not worried about code because I am away from all that - but I don't want to burn my house down.

100 amp requires # 3 wire copper and since you already have a conduit installed if I was you I would pull three # 3 THHN copper wires and one # 6 ground copper. It’s a little more expensive but a whole lot easier to work than aluminum but. Good luck

 

[Megawatt]

100 amp requires # 3 wire copper and since you already have a conduit installed if I was you I would pull three # 3 THHN copper wires and one # 6 ground copper. It’s a little more expensive but a whole lot easier to work than aluminum but. Good luck

Since you don’t care about the code # 4 copper would work because you will probably never pull 100 amps

 

[s1nemesis1s]

Since you don’t care about the code # 4 copper would work because you will probably never pull 100 amps

What is the max it allows - I am confused.

 

[s1nemesis1s]

So let me ask would 2-2-2-4 URD work?

 

[Megawatt]

What is the max it allows - I am confused.

# 3- 110 amps copper # 4 90 amps copper

 

[Megawatt]

# 3- 110 amps copper # 4 90 amps copper

My advice is to do it right with at least 125 amp main lug only panel installed in your garage. That’s a lot of amperage and your own house doesn’t probably worst case pull 50 amps at one time. I’ve wired MANY garages and buildings and usually just pull # 8 copper and never had a complaint. Your not going to burn your house down. I think that since you are a DIY you need to at least consult an electrician. There’s many things in the NEC that your not aware of and safety is the upmost importance.

 

[s1nemesis1s]

I keep seeing this come up Al MHF wire:

https://www.menards.com/main/electrical/electrical-wire-cable/electrical-service-wire-cable/2-2-2-4-aluminum-mobile-home-feeder-per-foot/3692059/p-1473854610601.htm

I like the price - I want a main disconnect in the garage as well - Can I run this in conduit? Anything wrong with the wire other than its aluminum? Any box recommendations? I need maybe 6-10 circuits, thinking a 90mp breaker.
Or should I go copper - and if so, what gaige 4-4-4-6? The alumnium is just so much more affordable.

 

[Megawatt]

I keep seeing this come up Al MHF wire:

https://www.menards.com/main/electrical/electrical-wire-cable/electrical-service-wire-cable/2-2-2-4-aluminum-mobile-home-feeder-per-foot/3692059/p-1473854610601.htm

I like the price - I want a main disconnect in the garage as well - Can I run this in conduit? Anything wrong with the wire other than its aluminum? Any box recommendations? I need maybe 6-10 circuits, thinking a 90mp breaker.
Or should I go copper - and if so, what gaige 4-4-4-6? The alumnium is just so much more affordable.

My friend just go with the aluminum it’s just a personal preference so instead of a main lug only panel buy one that already has a main breaker in it. They have 12 circuits and 26 circuits at Home Depot and Lowe’s. The breaker that’s already in it will be probably a 125 amp breaker, just replace it with a 90 amp double pole breaker. Yes you can pull either Aluminum or copper in a 11/2 conduit

 

[s1nemesis1s]

Thank you - this makes it so much easier and helps demystify the process. What size/sort of breaker should I put in at my main box? Should it be a 90 to match?

 

[Megawatt]

Thank you - this makes it so much easier and helps demystify the process. What size/sort of breaker should I put in at my main box? Should it be a 90 to match?

Yes that way you will have a discount in your new panel

 

[norcal]

It sounds like the garage is detached so unless having 6 or fewer circuits, a main will be required + a grounding electrode, such as a Ufer, AKA a concrete encased electrode, or a couple of ground rods driven at least 6 feet apart.

 

[Megawatt]

It sounds like the garage is detached so unless having 6 or fewer circuits, a main will be required + a grounding electrode, such as a Ufer, AKA a concrete encased electrode, or a couple of ground rods driven at least 6 feet apart.

NorCal you are not required to have ground rods on a sub fed panel. All the bonding takes place at the main service panel. You have to pull 4 wires to the building and add a ground bar if it doesn’t have one and isolate the grounds from the neutrals.

 

[norcal]

NorCal you are not required to have ground rods on a sub fed panel. All the bonding takes place at the main service panel. You have to pull 4 wires to the building and add a ground bar if it doesn’t have one and isolate the grounds from the neutrals.

If in the same structure then not required, but in a separate structure yes they are required, just no bond between the neutral & grounding conductor in the subpanel, & the grounding electrode conductor would land on the ground bar.

 

[Megawatt]

If in the same structure then not required, but in a separate structure yes they are required, just no bond between the neutral & grounding conductor in the subpanel, & the grounding electrode conductor would land on the ground bar.

You will need to find the article in the NEC which you should know is article 250 of the NEC

 

[norcal]

You will need to find the article in the NEC which you should know is article 250 of the NEC

See 250.32(A)

 

[Megawatt]

See 250.32(A)

Your close but read the exception to that particular article. That’s why I say pull 4 wires with one of them being the grounding conductor from the main panel. Think about it you don’t need ground rods at the building because you already have it through your equipment ground.

 

[norcal]

The exception is for a single branch circuit, including a multiwire branch circuit, a feeder still requires a electrode. The exception makes sense when you want to have a 20A circuit to a shed for a light, and/or receptacle(s), for example. Unless somebody was under a very old NEC, a 4-wire feeder is required, code permission for 3-wire feeders is long gone & a grounding electrode is still required for a separate structure unless a single branch circuit.

 

[Megawatt]

The exception is for a single branch circuit, including a multiwire branch circuit, a feeder still requires a electrode. The exception makes sense when you want to have a 20A circuit to a shed for a light, and/or receptacle(s), for example. Unless somebody was under a very old NEC, a 4-wire feeder is required, code permission for 3-wire feeders is long gone & a grounding electrode is still required for a separate structure unless a single branch circuit.

I can tell that you haven’t dealt with any inspectors. I’ve wired many buildings and garages and I have never drove a ground rod at any of them and I haven’t felled inspection. Let’s move on and quit arguing and we will agree to disagree