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Shop Adding 240V circuit to detached garage that already has 120V circuit?

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Xyphota

Ultra Member
Maybe this is more appropriate for the off-topic forum, but it's shop related. I am currently renting a property without a garage/workspace, and am using my parents garage (15 min drive away) for my workspace needs. I am considering new rental opportunities which include a garage so I could work out of a shop that doesn't require a commute to get too LOL. Needing 240V power for machine tools is a bit of a hurdle. What is the feasibility of adding 240v capacity to a detached garage if it is already receiving 120v power, assuming that a landlord were receptive to the idea? Is there anything I should be looking for during a viewing that would inform me if this would be easier on some properties than others? I have yet to see a garage with 240V power already available. Most properties for rent in my budget were built in the 50s-70s so maybe this is to be expected.
 
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DavidR8

Scrap maker
Administrator
Moderator
Premium Member
If there’s a sub-panel in the garage then it’s pretty easy.
Just need a double-pole breaker. The tricky bit might be running the wiring to the plug if the panel is built in flush to the finished wall surface. If the wiring is all exposed then it’s pretty easy.

Without a sub-panel it’s definitely more challenging.
 

Hruul

Lee - metalworking novice
That would require a new breaker and a replacement to the feed. Not an easy task, depending on how the wires are run. If the conductors are in conduit, you would have to confirm the conduit size is adequate for the new conductors you are wanting to run. If it is only receiving 120V power odd are it won't be a very big circuit, likely 15 or 20 amps only.
 

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
This all depends on the garage. In my mind, there is high probability that most garages already have 220, you just don't know it. As DavidR8 suggests, if it has a subpanel, it's probably already there and easy to access. But even those that don't may have brought a 220V cable into the garage to provide both sides of the circuit more easily and one could tap into that. Of course, code might be a problem.

Also look for stove, dryer, and welder outlets on the wall.

If all else fails, it's not usually a huge problem to run a new wire through the attic.
 

slow-poke

Ultra Member
As others have stated:
0) 120V requires 2 conductors+ ground, typical residential 240V circuit uses three wires + ground, so you have a pair of 120V circuits (two hots) that share the neutral. The two wire cables are flat, and the three wire cables are round.
1) starting point is to see if a subpanel exists in the garage.
2) If a subpanel does exist, open the hinged door (if it has one) and see what breakers exist?
3) Another option is to look at the panel in the house that is the source for the garage, and see what breaker(s) feed the garage, single breaker = 120V, double ganged breaker = 240V. Hopefully the breakers are labeled.
4) Also if there is a subpanel, see how many cables are entering the panel and if there is one that is noticeably larger, if there is try and read the text on that cable, it will answer most of what you need to know.

It is possible that they have 240V in the garage with a three wire cable, but are only using half of it, or they might only have run a two conductor cable and that would require a cable upgrade before you could do anything if you want 240V.
cb_box.png
 
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phaxtris

(Ryan)
Premium Member
Premium Member
code only requires 1 15a 110v circuit, therefore many garages only have 1 15a circuit, especially in the 50-70's

look at your house panel, and look for the garage breaker, if it is a slim 15a single pole breaker your hooped, in all likely hood it does not have the proper cable to the garage

i have, many years ago, just ran an extension cord through a basement window from the dryer plug for 220v
 

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
@Xyphota - help us help you.

Is this a detached garage? If so, how far away from the house?

Yard drawings.

If attached Garage - a rough floorplan for both. Just quick pencil with a few rough dimensions.

Photos of open garage panel if it has one.

Photos of open house panel with a pointer to garage breaker.

We can all go from there instead of guessing.
 

phaxtris

(Ryan)
Premium Member
Premium Member
To clarify, there is no house yet, I'm just asking about what I should be looking for in prospective rentals.

look for a sub panel that has a large breaker on top, greater than 15a, if it has 220 the garage will probably already look like more of a shop than a parking space

majority of garages dont have 220v, and it is quite a job to install it properly, trenches, permits, sub panels, larger inside breaker, etc etc

or there is the ghetto extension cord from the dryer
 

Tom Kitta

Ultra Member
In all cases I can think of sub panel means 240v is available. In almost all garages (standard ones) you do not have in 1950s - 1970s a sub panel. a 15amp, max 20amp single circuit is run from the house.

In almost all cases you would need to do rather expensive job of running underground cable from the house to a brand new sub panel in the garage and from that run your 240v outlet. This is work intensive and not cheap. Not exactly sure how landlord would allow this - ideally you should pull a permit for this job and either qualified electrician needs to do stuff or property owner - that is the legal need.

In short, not very feasible.

Yes, you can run an extension cord from the dryer BUT that depends on distance & probably open window in winter will not work too well.
 

Tom Kitta

Ultra Member
To clarify, there is no house yet, I'm just asking about what I should be looking for in prospective rentals.

Essentially ask if there is 240v in the garage or a sub panel. There is a slim chance the owner has multiple properties and does not know they have 240v.

As a landlord I personally would not mind if tenant pays for upgrades to my property - but I would insist on by the book approach. So you are looking at 1000s of CAD.
 

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
To clarify, there is no house yet, I'm just asking about what I should be looking for in prospective rentals.

That's kinda what I understood but the other questions made me doubt myself..... I'm easily misled by smart people.....

Okkkkk!

The best thing is that you already know you want 220! Since you don't have anything as yet, it seems to me that it's a no brainer to just draw a line between no-goes and goes. The line being a 220 subpanel or at a minimum a big 220 outlet.

Typically, you can ask up front. But if not, it's a 1 minute inspection.

If it were me, I'd either be looking to live there or want a detached shop. I wouldn't want a shop in someone else's garage.
 

trlvn

Ultra Member
One way you might get the landlord to play ball is that the number of electric vehicles is increasing all the time. Tenants are likely to demand support for charging in the future so maybe now is the time to invest in the necessary wiring. A basic 220V outlet for you is a very minor addition at that point.

Craig
 

Xyphota

Ultra Member
One way you might get the landlord to play ball is that the number of electric vehicles is increasing all the time. Tenants are likely to demand support for charging in the future so maybe now is the time to invest in the necessary wiring. A basic 220V outlet for you is a very minor addition at that point.

Craig
That's a great point, I think that's how I'll ask the question. I think most landlords would not be very ecstatic about a hobby machine shop getting setup on their property LOL.
 

phaxtris

(Ryan)
Premium Member
Premium Member
Yes, you can run an extension cord from the dryer BUT that depends on distance & probably open window in winter will not work too well.

when i did this i made an insulated blank to fit in the window opening, winter was not a problem
 

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
That's a great point, I think that's how I'll ask the question. I think most landlords would not be very ecstatic about a hobby machine shop getting setup on their property LOL.

There is a kill-joy in every crowd. It's my turn. The LAST thing I would ever want is some guy charging an electric vehicle in my garage. Wouldn't happen. Period. Grounds for eviction. Same goes for remote start. Outside only. Period. No ifs ands or buts.
 

Xyphota

Ultra Member
For fire safety reasons? I would have guessed that the vast majority of all electric cars are charged inside a garage.
 

Darren

Ultra Member
Premium Member
A freind bought a house with a detatched garage. It had a 100a sub panel in the shop. Someone cheaped out and fed it with #10 though, so its only actually a 30a feed. So be careful. you could even have 15a 240v, which would very pretty useless for a shop..
 
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