What wire do I need to run subpanel to main panel?

[bmsemple1]

I want to add a 100 amp subpanel in my garage but I'm having trouble determining exactly which wire I need to run to the main panel. It will be approximately 75 feet away from the main panel. I thought I needed 2-2-2-4 but I've also read that I could use 3-3-3-5 copper SER cable. I've discovered that these wires are more expensive than I thought. Any tips on where to buy it? I've already called several local electrical supply places and I'm being quoted $500 or more.

 

[pattenp]

Is garage detached and feeder going underground?

 

[bmsemple1]

No the garage is attached and the cable will not be underground.

 

[pattenp]

You can use 2-2-2-4 Al SER for 90A, 1-1-1-3 Al SER for 100A, or 3-3-3-5 Cu SER for 100A. SER installs like NM-b and needs protection if subject to physical damage.

 

[wyliesdiesels]

#2 al is good for 90a not 100a.

If you really need 100a then you will need #1 al or #3 cu.

But 75' of al ser shouldnt cost $500.

I will find some prices for u when i get home.

 

[ddawg16]

100A? Really?

Especially 240Vac....

Why?

 

[Norcal]

#2 al is good for 90a not 100a.

If you really need 100a then you will need #1 al or #3 cu.

But 75' of al ser shouldnt cost $500.

I will find some prices for u when i get home.

The OP is specing copper conductors. Aluminum would be a good way to reduce costs.

 

[wyliesdiesels]

I want to add a 100 amp subpanel in my garage but I'm having trouble determining exactly which wire I need to run to the main panel. It will be approximately 75 feet away from the main panel. I thought I needed 2-2-2-4 but I've also read that I could use 3-3-3-5 copper SER cable. I've discovered that these wires are more expensive than I thought. Any tips on where to buy it? I've already called several local electrical supply places and I'm being quoted $500 or more.

ok so #3 cu SER may be $500 but #2 al SER is no where near that price.

https://www.wireandcableyourway.com/2-3-4-ground-ser-aluminum-building-wire.html

80' for $110

If you want 100a:

https://www.wireandcableyourway.com/1-3-3-ground-ser-aluminum-building-wire.html

80' for $134

100A? Really?

Especially 240Vac....

Why?

huh?

 

[wyliesdiesels]

The OP is specing copper conductors. Aluminum would be a good way to reduce costs.

yes but the way he worded it made it sound like both al and cu were that expensive....

 

[pattenp]

Nothing wrong with using Al SER. I'd go with the aluminum over copper because of the cost.

 

[bmsemple1]

Thanks everyone. We are adding a 700 sq ft addition on top of our garage. I also want to make sure I have enough for workshop machines running like fans, heaters, welder, saw, etc. In the future there will be additions on the back of the garage and I want to make sure I have enough power to run another box. It might power a small living quarters and pool equipment someday.

 

[rburke65]

Why is the OP wanting 100Amp to his garage so unusual ?

 

[wyliesdiesels]

Thanks everyone. We are adding a 700 sq ft addition on top of our garage. I also want to make sure I have enough for workshop machines running like fans, heaters, welder, saw, etc. In the future there will be additions on the back of the garage and I want to make sure I have enough power to run another box. It might power a small living quarters and pool equipment someday.

Well in that case i would start off with a load calc.

You dont want to out 100a in then discover down the road that you meed more.

Do it right the first time.

It boggles my mind how most dont do load calcs...

That should be the first step for someone that wants to add that much load in the future.

Planning planning planning!

6 Ps....