Rewiring garage Subpanel for 220volts, need advice.

Page 2 of 2  


I believe the NEC only allows for a single circuit out to the outbuilding, if you want more, you need to put in a sub panel in that outbuilding.
60 amp (#6 wire) circuits can be run in 3/4" conduit, which reduces the cost, most bang for the buck so to speak.

To provide a 220 service out to the garage, you'll need 3 wires, two hobs plus neutral (and ground).
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Why would he need a neutral? 240v/20a outlets don't even have neutrals on them.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I'm making an assumption that there is a need for 110v, for lighting if nothing else.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The garage is just below the bedrooms, it is not outbuilding.

How about 100 amps subpanel what size wire and conduits?

The sale associate in HD told me 12/2 will be just alright for 220/20 amps wires. Now, I could return them for the size I need.
How much do you think I will have to spend to get an electrician to do the work I posted earlier and plus the work to rewire the bedroom away from the garage lighting circuit?
Thank again....
PS: The questions may be stupid, I'm learning and change as I get more responds.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Then you have a few more options.

Probably, #2 and inch and quarter conduit (or 1.5). Not sure, depends in part on the distance and such.

For 220 only yes, if you want to run a sub-panel, and provide 110 then you need the neutral.
IMHO, a neutral is a good idea, because then you can change back to 110 vac with a simple outlet change.

Depends mostly on how much construction he has to do to run the wires. If everything is nice and open, I'd guess 2-3 hrs, at what ever his rate is.

The only stupid question, is one asked when one already knows the answer.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

You don't need a neutral to change back to 120v. One of the hots becomes the grounding conductor. You only need a neutral if you want to run 120v and 240 at the same time; probably not a good idea.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Or an Edison style circuit, which uses the common neutral, and allows full current on each side of the outlet.
I did this in a old house I rewired, where the owner went with central ac after I worked to pull 220/30amp to the upstairs bedroom for a window unit. Installed 20 amp outlets in an edison circuit, and told the owner it is heavy duty, this is where you'd plug in a steam cleaner or something like that.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

After listening to all of this, I would install two new 12-2 cables from your main panel to the garage. One would be 120V, 20A with a GFCI receptacle as the first one. Put as many receptacles on this as is convenient for all your 120V tools. The other 12-2 would be for another 240V 20A circuit. These can also have multiple receptacles so you can place them where you want them and keep daisy chaining the 12-2 until you're done. You can add more receptacles to your existing 240V 20A circuit if that would make things more convenient. You just have to limit things on each circuit so you're not tripping the breaker (one big and one small item would be ideal).
If you put in a subpanel, you still have to buy everything above, but you'll use somewhat less 12-2 and a fair amount of 6-3 (for a 60A panel). A subpanel will also require the cost of the panel and the 60A double pole that protects the feeder. If you really think you're not going to have enough power, you can install a 3'rd cable along with the other two 12-2's. The three cables should fit in13/16 holes in your studs/joists (6-3 NM would fill the 13/16 hole itself), and you're still within the temperature derating limits with even a 4th cable.
-- Mark Kent, WA
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:
Now, I'm narrowing down to either two new 12-2 cables or one 60A subpanel as you describe below. I will have to limit a 220/20A to one big and one small 220volts machine at any one time (still doubtful), while the other 220/20A to just one machine and the 3rd ones for 120V/20A and lighting.

===========>the 60A double pole that protects the feeder. If you really think you're not going to have enough

I'm a bit confuse here, I have a finished garage. The studs are encased with dry wall. I am planning to run two new 12-2's (one 120V/20A and the other 220/20A) from the main panel, taking the same path studs/joists. .. What do you mean by "within the temperature derating limits with even a 4th cable.?"
Thanks for you help
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

on
circuit.
circuit
you're
Can you list the equipment you have and the motor nameplate amps at 240V for each? If so, we should be able to tell you what can run together on the same circuit. I would expect the dust collector to draw its nameplate amps. Saws, jointers, planers, etc only draw their rated current when cutting wood. If the motor amps used simultaneously on the same circuit add up to 20, things should work. Keeping that sum at 16 to 18 would be better though.

When you run multiple wires together, you have to derate the amount of current they carry because heat from one wire heats the other wires too. This is true whether you're stuffing a bunch of wire in a conduit, or running bundles of cable. With cable labeled "NM-B" (which is what Romex made after 1985 will indicate), you can run up to 9 current carrying wires in a bundle before #12 can't carry 20 amps anymore. Should you need more than 4 cables to the same location, you just run two separate bundles (say 3 cables and 2 cables) spaced a few inches apart so heat from one doesn't add to the other. This works anyway, because you don't want a hole larger then 1" in your 2x4 studs so that you can keep the wires 1.25" from the face of each stud. You won't get more than 4 cables in a 1" hole.
-- Mark Kent, WA
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Vital question. Is the garage attached or detached. If the garage is a separate structure then the sub panel would be the only way to proceed that would comply with the US National Electric Code (NEC). Each building must be supplied by a single branch circuit or feeder. The exceptions to that rule rarely apply to residential properties. -- Tom H
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
William wrote:

The cheapest and easiest solution is to add a couple of additional 220V outlets to the 220V/20A circuit *that you already have*, and rewire your table saw motor for 220V. You just need a roll of 12/2wg wire and a few switch boxes (or handy boxes and wire clamps) and 220V grounding outlets: - - or - |- o o
The dust collector and jointer probably do not draw anywhere near their rated amperage. The table saw probably does, but only when it is starting up or when you are cutting something thick.
If you have your heart set on a new subpanel, you can buy a 100A main lug panel with 6 spaces for about $15. You will have to install a ground bar kit (just a couple of dollars) and remove the green bonding screw to isolate the neutral from the metal box. Run 6/3wg cable from a 60A 2-pole breaker in your service panel to the lugs in the subpanel. Or if you are cheap, and you never plan to put a welder in your garage, use 10/3wg cable and a 30A 2-pole breaker.
Best regards, Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

OK, so far I'm with you. I already have the 12/2wg. What do you mean by 220V grounding?

My jointer is a 2 hp and planer is 3hp. However, I used them once a while when I need to plane a batch of rough saw lumber for a project. The table saw really draw every ounce of juice from the present circuit.

I do have a 180a, AC welder, it's set up to run on 220/20a. I'm confuse on the 6/3wg?
Thanks, getting nearer there.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
William wrote:

I drew a picture (sort of.) Two hot wires and a ground. Tap into the existing circuit and add a couple of new outlets. Turn it into a 20A branch circuit.

But you don't run a dust collector with it, or any of the other power tools, so you'd still be OK with the existing 20A circuit. Some popular 230A welders require a 50A circuit.

6/3wg cable if you want to put in a subpanel fed through a 50A or 60A breaker. If you can get by with a 30A subpanel, you can use 10/3wg cable. The "wg" part means "with ground", because you need 4 conductors. I'm not sure, but I think you can still buy large 3 conductor cables without a ground, so I said wg just to be safe.
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Rewired and tested my 1HP Crapsman table saw today from 110/14amps to 220/7amps. It's more powerful running in 220volts and it started without hesitation. I also turn on my compressor with the TS running and it did not trip the circuit. I guess it's safe for me to run both at the same time.
I guess I will be starting to pull the two 12/2's from the main panel to the garage sometime soon and complete everything before Spring.
Thanks everyone for the help. I wish everyone here a Happy and safe New Year!
Thanks again!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I wasn't following the thread, Are the T/S and comp.on the same circuit? Tony.
I also

I
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.