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I want to add power outlets to a side of my garage that currently has none but am struggling to find wiring diagrams for a 240v switch that will be connected to an outlet. Is it as easy as 2 hots connected to the bottom two screws of a double pole switch and then 2 hots out of the top two screws with a ground wire attached? I just haven't had any luck finding anything to confirm this.

My garage functions as both a hobby space and where my kids store their bikes, scooters, etc. I want to wire switches upstream of the outlets so I can keep my tools plugged in and not be concerned about a child messing around and accidentally turning a tool on.

Garage Wiring

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    I take it the circuit breakers for your garage circuits are nowhere near the garage? Mar 4, 2021 at 23:41
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    It is that simple, but don't underestimate yours kids willingness to activate more than one switch when they have a case of curiosity. I highly recommend a long and boring explanation of the dangers of each tool. Talk at least 2 minutes past their eyes glazing over. Mar 4, 2021 at 23:49
  • The circuit breakers are in the same garage. I need outlets on the opposite side of the garage than the power panel. As for kids, my concern is with smaller children that could pull out the switch on a table saw but not be tall enough to operate switches.
    – Remy
    Mar 4, 2021 at 23:54
  • @Remy -- does the panel in the garage serve the whole house, or just the garage? Mar 5, 2021 at 3:14
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    Both are required in / for all receptacles, the GFCI protection can be from the panel or a GFCI receptacle that the load terminals feed the rest of the string.
    – Ed Beal
    Mar 5, 2021 at 17:15

3 Answers 3

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To switch 240v there are 2 methods. Cheap method single pole switch break 1 hot that’s it. the circuit is still live 120v could be measured to ground but a 240v device will be turned off. I have seen this used extensively on heating circuits. I have also found this in older tools like radial arm saws, and table saws that were multi voltage. The down side the tool has 120v potential to ground when off. Advantage it’s cheaper.

Today The more common way is to use a double pole switch and break both hot legs. This kills all power going to the tool It cost a bit more. Is considered safer because no power to the tool but a 240v device doesn't care. Which method is used.

If you want to use standard snap switches on motors if not motor rated a switch with 2x the current requirement is needed.

For general loads ( other than motors) the switch only needs to be rated for the load.

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  • I plan on running a 3HP table saw using a 6-15 outlet downstream of the switch. Would a double pole switch rated at 20amps not be correct for this application? I was considering a switch like this one: platt.com/platt-electric-supply/…
    – Remy
    Mar 5, 2021 at 1:31
  • No, it is only 2 hp rated. Try a ms303-ds amzn.to/38aMAex 5 hp@ 240v Mar 5, 2021 at 2:19
  • Do I have to have a motor rated switch if I am not using it to control the motor? My intent is not to turn the power on and off through the switch but to provide power to the outlet and then turn the table saw on.
    – Remy
    Mar 5, 2021 at 2:20
  • Well by code a 3 Hp motor 240v is 17 amps so it should be at least a 30A unless motor rated for 3hp. The switch you have is only rated for 2 Hp. If you are only using it for a safety not opening and closing under load it might hold up. For circuit ampacity motors require 125% of the fla so you need a 20 amp circuit and receptacle also.
    – Ed Beal
    Mar 5, 2021 at 2:25
  • From the manual: "The Professional Cabinet Saw model number PCS31230 comes with an AC motor that is rated at 3 hp and operates at 60 Hz. It can be used with single phase 208-240V power. The motor draws 13 amps at 208-240V power." The saw uses as 6-15 plug so that means I have to use a 15amp circuit breaker to match it, correct? And I should be able to use this switch in case it was used unintentionally to start the saw: platt.com/platt-electric-supply/…
    – Remy
    Mar 5, 2021 at 2:33
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A single receptacle has to be full circuit amperage [NEC 210.21(B)(2)], so the 15A (NEMA 6-15) receptacle would be connected to 15A breaker or you need a NEMA 6-20 or a duplex 6-15. Normally a 6-20R is a T-slot and will accept a 6-15P.

Also the 2020 NEC specifies 240v receptacles in garages now require GFCI protection too [210.8(A)(2)].

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  • I don't believe Washington State requires the GFCI, am I reading this correctly? 008(B) Other than dwelling units – GFCI requirements. (3) GFCI requirements. GFCI protection for personnel will not be required for: (a) Three-phase receptacles unless specifically required elsewhere in the NEC; or (b) Receptacles other than 125-volt, single phase, 15- or 20-ampere used for: recreational vehicle supply equipment or for attachment of a mobile home supply cord.
    – Remy
    Mar 5, 2021 at 4:29
  • I don't think you are. "008(B) Other Than Dwelling Units" correlates with "NEC 210.8(B) Other Than Dwelling Units". 008(A) modifications for 210.8(A)Dwelling Units only gives modifications to the NEC, if it were a complete replacement for that section then no GFCI's would be required at all. And even then I think, due to the colon, the modification for non-dwelling unit only applies if used for RV or mobile home connection. Mar 5, 2021 at 6:20
  • Remy if you are in Washington state they are on the 2020 code. The 2017 code req all 120v receptacles in garages to provide GFCI protection. The 2020 code requires all 125v through 250v receptacles to have GFCI protection 210.8.A. And 210.8.A.2. I am a licensed electrician in Oregon and we have a reciprocal license agreement because our states have similar enforcement of the code. You may have a local exception i an not currently working on your side of the Columbia so I haven’t checked the exceptions but the 2020 code has been approved and is In use by Washington state. We are trying to help
    – Ed Beal
    Mar 5, 2021 at 14:52
  • @EdBeal Thanks for the help! I really do appreciate it. So a 240v GFCI breaker would be something like this for a Homeline panel: homedepot.com/p/…
    – Remy
    Mar 5, 2021 at 17:15
  • Yes that breaker would meet code requirements for the 240v GFCI. Thanks on the site are up votes and or accepting an answer the check mark it shows the information was useful or you used it. You can upvote multiple items or answers but only accept 1.
    – Ed Beal
    Mar 5, 2021 at 17:28
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While your approach with switched receptacles works...

While your approach using an external switch to control the receptacles works, and can be made fairly robust using a key-operated lightswitch like what's shown below:

Leviton 1221-2WL

, it does have the downside that you need to give each circuit its own switch, which doesn't scale as you add circuits.

The alternative: feeder and lockoff

A more scalable alternative to the individual keyed switches is to reroute the shop circuits to a main lug subpanel in the garage, then put a breaker lockoff device and a suitable padlock on the feeder breaker for the shop. That way, you have only one thing you need to unlock and lock to turn the shop on and off.

Similarly, you could use a main breaker in the subpanel with a locked on the subpanel's door. You could even implement it using a separate lockable switch or breaker in its own box; this would allow you to use a breaker (such as an ABB/GE S800U or Schneider Electric/Square-D Multi9 C60BP) that can be fitted with both a lockoff and an undervoltage release coil, which allows you to implement a shop-wide E-stop function for a price that's not completely eye-watering.

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    I highly recommend your final suggestion. I did something similar in my recently built workshop. I have a subpanel with a main breaker and locking cover that feeds all the larger tools. I can lock them all down by shutting off the main breaker and locking the panel door.
    – Mark
    Mar 6, 2021 at 1:56

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