Wire size

[Dave Norris]

HI,
I need to run a wire from my main service in my house to a panel in the shop, about a total run of 75ft. The house is a 200 amp service, and I'd like to put 100amp in the shop. Any ideas on what size/type wire to use?

Thanks
Dave

[David Nelson1]

Hey Dave,
I used 6 gauge (not correct I can't verify the gauge because I'm not home) 4 wire copper cable when I put my 100 amp sub in. Below is a link you might find helpful. I sure did.
The whole OD of the cable was around 3/4 inch and it doesn't bend very well. I took quite a bit of muscle to feed it through a 2 1/2 inch plastic conduit. I had about 6 feet to span from the house to the shop. Dug down 24 inches with a jack hammer because it was in the middle of winter here. The box, wire cable, conduit, a few breakers and a few hammer drill bit was less that 500.00 The cable I used was not rated for outdoor or buried use.

EDIT: I would like to correct this post. I should have posted that I didn't remember the gauge size.

http://www.hammerzone.com/archives/e...1/overview.htm

[Micheal Roth]

I run #2 copper 4 wire Tray cable 65' to my shop. I run it in 2" electrical conduit in a trench 18" deep. I believe the electrical supply store said it was rated for up to 135 amps at that 65' run.

[Van Huskey]

Hey Dave,
I used 6 guage 4 wire copper cable when I put my 100 amp sub in. Below is a link you might find helpfull. I sure did.
THe whole OD of the cable was around 3/4 inch and it doesn't bend very well. I took quite a bit of muscle to feed it through a 2 1/2 inch plastic conduit. I had about 6 feet to span from the house to the shop. Dug down 24 inches with a jack hammer because it was in the middle of winter here. The box, wire cable, conduit, a few breakers and a few hammer dril bit was less that 500.00 The cable I used was not rated for outdoor or buried use.

http://www.hammerzone.com/archives/e...1/overview.htm

I am curious I didn't even look at the link but #6 has an ampacity well below 100 amps!!! For 100 amps you need at least #2 just going on memory, #6 is good for about 55-65 depending on the type of insulator, again from memory.

[Scott T Smith]

HI,
I need to run a wire from my main service in my house to a panel in the shop, about a total run of 75ft. The house is a 200 amp service, and I'd like to put 100amp in the shop. Any ideas on what size/type wire to use?

Thanks
Dave

Wire size is determined by current (amps), material (copper versus aluminum), insulation (temperature rating), distance (for resistance and voltage drop calculations), and environment (quantity of wires and if they are in open air, inside conduit, direct bury, etc).

Most of my reference books indicate that #2 would be the minimum size, although you may exceed 2% voltage drop if you were pulling 100amps through it.

[David G Baker]

#2 copper for 100amp 75 foot run is what I would use and I would run 4 legs.

[George Clark]

The cable I used was not rated for outdoor or buried use.

Why in the world would you then use it outdoors and bury it?

[Van Huskey]

Why in the world would you then use it outdoors and bury it?

I assume what he meant was it was not direct burial rated wire and he did say he buried it in conduit.

[Adam Strong]

#2 copper, 4 leg, UF (direct burial) is what I have running to my shop which is about 60ft from the house (75ft or so from the main panel) and feeds a 100 amp panel. This was done with a permit and inspection, so I know it's up to code and done right.

[David Nelson1]

I might have used #2 but I'm not @ home so I can say. I just went by the link I sent because that is the tech info I used to run the wire and hook up to the sub panel not the wire gauge. I'll go back and correct my original post. Thanks for keeping me straight. We don't need bad info posted. I do know the white wire barely hit in the side terminals.

I am curious I didn't even look at the link but #6 has an ampacity well below 100 amps!!! For 100 amps you need at least #2 just going on memory, #6 is good for about 55-65 depending on the type of insulator, again from memory.

[David Nelson1]

I assume what he meant was it was not direct burial rated wire and he did say he buried it in conduit.

Exactly!!!

[Brian Cover]

HI,
I need to run a wire from my main service in my house to a panel in the shop, about a total run of 75ft. The house is a 200 amp service, and I'd like to put 100amp in the shop. Any ideas on what size/type wire to use?

Thanks
Dave

Number 2 THHN or THWN wire in conduit is the best choice without breaking the bank. Direct burial is never a good idea. Conduit 24" below grade is much more safe and durable. I used 1.5" grey PVC and pulled 110 feet with the help of my 13 year old son. Check local codes for conduit material selection and required depth of the conduit. Your building dept will be happy to give you the right answers.

[Dave Norris]

Thanks for the replies. I'm actually having the electrician who wired the house do the panel in the shop. Time was when I would have been doing it myself, but after so much conflicting info, I figure best to let it to the pros. I'll be doing the individual circuits in the shop, but the panel itself is just plain old over my head.

I was just curious as to the size wire to try to get a handle on what the whole shebang is going to cost. The wire will be in conduit about 24" in the ground.

As far as panel size, I never come close to using 100 amps in the shop. The most that ever happens at one time is the DC, and a saw or planer or jointer or shaper, all of which are wired for 220. I currently have 75 amp service in the shop I'm in now and have never had a problem. The house is 125 amp service right now. I've even run the DC, TS, and the jointer at one time. I just didn't start them all at the same time.

The contractor who built the house and the electrician who wired it think the 100 amp is the way to go and won't cause any problems with the house. I was actually in favor of 75 amp again.

Ultimately I'd eventually like to get a phase converter and run a big ol' radial arm saw, so the 100 amp should handle that ok I think.

Thanks again.

[Rollie Meyers]

Thanks for the replies. I'm actually having the electrician who wired the house do the panel in the shop. Time was when I would have been doing it myself, but after so much conflicting info, I figure best to let it to the pros. I'll be doing the individual circuits in the shop, but the panel itself is just plain old over my head.



As far as panel size, I never come close to using 100 amps in the shop. The most that ever happens at one time is the DC, and a saw or planer or jointer or shaper, all of which are wired for 220. I currently have 75 amp service in the shop I'm in now and have never had a problem. The house is 125 amp service right now. I've even run the DC, TS, and the jointer at one time. I just didn't start them all at the same time.

The contractor who built the house and the electrician who wired it think the 100 amp is the way to go and won't cause any problems with the house. I was actually in favor of 75 amp again.

Ultimately I'd eventually like to get a phase converter and run a big ol' radial arm saw, so the 100 amp should handle that ok I think.

Thanks again.

75 ampere is not a standard rating for fuses / circuit breakers, it goes from 60 to 70 then jumps to 80.

240.6 Standard Ampere Ratings.
(A) Fuses and Fixed-Trip Circuit Breakers. The standard
ampere ratings for fuses and inverse time circuit
breakers shall be considered 15, 20, 25, 30, 35, 40, 45, 50,
60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300,
350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000,
2500, 3000, 4000, 5000, and 6000 amperes. Additional
standard ampere ratings for fuses shall be 1, 3, 6, 10, and
601. The use of fuses and inverse time circuit breakers with
nonstandard ampere ratings shall be permitted.

From 2008 NEC.

[Dave Norris]

I checked the panel in the basement, and it is in fact a 70 amp breaker. I stand corrected...

...which is why I'm letting the electrician do the panel wiring