110v out of 220v ?

[SARGE..g-47]

Yuri... I don't normally get into conversations concerning wiring but.. to someone that does understand wiring you have the capability to run two 110 V lines off the existing un-used in the utility room. To someone that does understand wiring this is a simple task as out-lined by Art.

But.. the key to his commenst lies in the last sentence which is.....

"If you don't understand all the above get an electrician to help".

With all due respect to you.. after reading this thread I am not sure you totally understand and there lies the problem. It would be great to save a few dollars and do it yourself but... it would not be so great to burn your house down because you thought you understood IMO.

I would take a deep breath.. be honest with myself and decide if you Totally understand as anything else as I see is is both dangerous to you and your family. Wiring is something you better get right the first time or there may not be a second chance! You best hire and electrician or have a friend that Totally understands set up the simple procedure that can give you two additional 120 V lines if you wish.

Regards and good luck in your decision....

[LCHIEN]

as the others have said, if your dryer outlet is a 4-wire then your best bet is to place a small subpanel with a 30Amp 2-pole input breaker and then you can have 4 or maybe even six 15Amp 115 outlets. I'm saying six because although that adds up to 45Amps per leg, the 30Amp breaker wil limit it to safe levels and in all probability you won't be using all legs to 15Amps. E.g. your house circuit breakers will often add up to more than the inlet breaker because you don't have all the circuits maxed out all the time. For example putting the lighting, radio, and small stuff on one circuit you probably will have much less than 10 Amps. you may have to do a little load balancing but its possible.

If you have a three-wire 220V outlet then you are lacking a neutral line and it wll be more complicated. In that case, the simple plan is to move one of the 220V hot wires to the neutral bar, put in a single pole breaker and only get 120V 30Amp service to a sub panel and put two or three 120V circuits breakers from that.

[tseavoy]

I have my shop fed by a 220V circuit in the house. I just used an unused 30A 220V heating circuit from the house panel and ran it out to the shop (about 80 feet away) using underground 10/2+ground wire. I installed a subpanel in the shop consisting of one 220V outlet and two 110V circuits protected by 20 amp breakers. I did put in a separate ground rod, tied to the subpanel. It has been that way for years.
A four wire 220V circuit is just a 3 wire with a separate ground, redundant to the grounded neutral.

Tom on Marrowstone

[crokett]

.
A four wire 220V circuit is just a 3 wire with a separate ground, redundant to the grounded neutral.

Tom on Marrowstone

Correct. But if you feed a sub with a 3 wire 220V circuit, this means your ground/neutral are bonded at both the sub and the main panel. This is not allowed by code. I'm not saying it won't work, just that it is a bad thing. By code, your house electrical should have the ground/neutral bonded in only one place. Sometimes it is the meter base, sometimes it is the main panel. Any subs you wire in should be fed by a 4 wire circuit - 2 hots, ground and neutral and the ground and neutral busses in that sub must be separate. the sub in my basement is wired with separate ground and neutral busses and my shop panel is (or will be) wired the same way.
For equipment it doesn't matter. They can be either 3 or 4 wire @ 220 but a subpanel should correctly be wired with 4 wire 220V.

Equipment can be either a 3-wire or 4-wire 220V circuit. The OP has a 3-wire circuit. So his safest and easiest option is to turn it into a 30A 110V circuit by moving one of the hot legs to the neutral bar in his panel.

[woodturner]

But if you feed a sub with a 3 wire 220V circuit, this means your ground/neutral are bonded at both the sub and the main panel.

Latest NEC specifies that the neutral be carried to the panel but that the panel be grounded locally.

You could use a 3-wire 220V circuit (2 hots, one neutral) and provide a local ground for the panel and garage wiring. HOWEVER, you can't bond the ground to the neutral, as you said.

[crokett]

Latest NEC specifies that the neutral be carried to the panel but that the panel be grounded locally.

You could use a 3-wire 220V circuit (2 hots, one neutral) and provide a local ground for the panel and garage wiring. HOWEVER, you can't bond the ground to the neutral, as you said.

Hmm... then that has chanaged. Thanks for the info. I do know the sub has to be grounded locally. Actually it might make things a little cheaper on my shop panel because I am thinking 2-2-2 aluminum is cheaper than 2-2-2 4.

[kbkreisler]

A detached building sub-panel requires a local ground rod, but in an attached building as this is, a sub-panel does not. However you cannot bond the com/gnd at the sub-panel, you must remove the bonding screw and add another terminal strip to seperate common and ground wiring, Both the common and ground terminal strips need to be wired back to the main panel with properly sized conductors.
Another notable change in last years NEC is that it is now illegal to share a common between 2 or more circuits.

[crokett]

A detached building sub-panel requires a local ground rod, but in an attached building as this is, a sub-panel does not. However you cannot bond the com/gnd at the sub-panel, you must remove the bonding screw and add another terminal strip to seperate common and ground wiring, Both the common and ground terminal strips need to be wired back to the main panel with properly sized conductors.

So if I understand correctly, a sub in a detached building since it requires its own ground rod anyway could be wired with two conductors and ground but no common while a sub in the same building would require 2 conductors, common and ground?

[master53yoda]

So if I understand correctly, a sub in a detached building since it requires its own ground rod anyway could be wired with two conductors and ground but no common while a sub in the same building would require 2 conductors, common and ground?

i think you meant that you could run 2 hot and a neutral with a ground from the ground rod in a remote building. in the same structure you would need 4 wire

Just a question, why are you running such large wire to your shop #2 is capable of 75 to 80 amps. There is no way you need that much power in a one man shop. mine is a 50 Amp 240 4 wire system and i don't ever come close to loading it. the closest i come is running the 3 hp compressor, 2 hp dust collector with a 5" to the planer, and a full 3 hp planer on 2 x 12s and the lights. One leg is drawing 28 to 30 amps and the other is drawing 22.
What are you possibly going to run that would need an 80 amps service. Electric heat maybe???
The only thing i could think of that might load mine close to full is if my wife is running the kiln and i was working in the shop, but we only run the kiln over night when my work shop load is low.

[crokett]

The panel is a 100A panel. It came with the shop. The guy I got it from was a contractor so maybe he needed it. Do I -need- 100A? No. However the effort to install it - digging the trench, conduit, etc is the same and there isn't that much difference in price between #2 and #4 or #6 at least for aluminum. So I figure install the #2 now and that way I don't have to worry about it again. The shop panel is also powering (or will power) the small shed we have, plus a pool and whatever else my wife can dream up.

[cabinetman]

However the effort to install it - digging the trench, conduit, etc is the same and there isn't that much difference in price between #2 and #4 or #6 at least for aluminum.

I think I would use copper instead of aluminum.
.

[crokett]

I think aluminum is about $1.60 per foot for 2-2-2-4 and copper is over twice that. Or was last month when I checked prices. With the 70-80 feet I need, that is a lot of money. So I am using aluminum.

[cabinetman]

Copper is better.
.

[tseavoy]

So you would be feeding a 100A panel from a 30A dryer circuit? If that's the case, just use the 100A main breaker in the panel as a disconnect switch. The house 30A breaker would trip long before any load would trip the 100A breaker.
I would use 8 gauge copper wire for the feeder from the house. I used 10GA and I wish I used a heavier wire. Copper to aluminum connections are sometimes troublesome.


Tom on Marrowstone

[Crash2510]

Copper is better.
.

yes copper is a little better ( withstands heat better and can carry more current) but at nearly twice the cost it is not very feasible for most. A properly sized service with aluminum will work just as well with copper as it does aluminum. And this is from an electrician that has done 4 350' + services this week (oh my back-lol). We have never had a problem with any services we have ever done more than 20 years. The problems arise when the job is done improperly( undersized, no deox is used). Just my well informed opinion.