Receptacle locations... garage project.

[glenn bradley]

Like others have said; lots of them and above 48" high. I run my 120/240 saw at 120 as I see no performance gain and it saves me a breaker slot. I also have one light circuit on the house mains and the other 2 on the sub. I didn't want to be left in the dark if I ever blew the sub-panel feed breaker. Hasn't happened yet ;-)

[John Sanford]

You may want to consider that you'll need a minimum of 3 distinct dedicated 220v circuits. One for the DC, one for the running major machine, and one for a 220v compressor.

Mike, Rod may be suggesting GFCI breakers in the panel. That's the route I took with my shop when I had it. I, however, never got around to putting any 220v circuits in before I sold the house, so I don't know if/how you could do a mixed 120v/240v (yes, I know I keep switching between 220v and 240v, 'tis the same to me in this context) circuit in actuality, rather than simply potential.

[Van Huskey]

Rod - how do you put GFCI on that multi wire circuit? Seems you'd need a GFCI unit in each box.

Mike

Many if not most kitchens today are wired on multi-wire branch circuits due to the 2 circuit requirement (where both circuits are close together) and the need for them to be GFCI protected. You put a GFCI receptacle in the first box for each branch then the rest of them can be protected of the initial GFCI down the line as long as you wire the GFCI in the proper fashion. The whole thing takes wonderful advantage of out of phase hots sharing a common. The one thing you HAVE to do is make sure the two hots are out of phase, the normal and easiest way to make sure this is the case is put both breakers side by side or use a 2 pole breaker which you would do anyway if you want a mixed voltage circuit like Rod is talking about.

I use multi-wire branch circuits to run 120v around the shop. By running 12-3 to around to each double box (not suggesting a home run for each unless you need that sort of capacity) you can wire 2 duplex outlets each with 20 amp capacity but without having to run two 12-3 wires.

You could also put GFCI breakers in as John mentioned which as long as your panel is close would work but it usually costs more than GFCI outlets.

[John Coloccia]

The one thing you HAVE to do is make sure the two hots are out of phase, the normal and easiest way to make sure this is the case is put both breakers side by side or use a 2 pole breaker which you would do anyway if you want a mixed voltage circuit like Rod is talking about.

If I remember correctly, the NEC now requires a ganged breaker when using a shared neutral. I had to do a couple of those due to box fill issues I had, and seemed to recall that it wasn't code yet but that it would be the following year. I did it anyway as it's just a good idea.

[Mike Henderson]

Many if not most kitchens today are wired on multi-wire branch circuits due to the 2 circuit requirement (where both circuits are close together) and the need for them to be GFCI protected. You put a GFCI receptacle in the first box for each branch then the rest of them can be protected of the initial GFCI down the line as long as you wire the GFCI in the proper fashion. The whole thing takes wonderful advantage of out of phase hots sharing a common. The one thing you HAVE to do is make sure the two hots are out of phase, the normal and easiest way to make sure this is the case is put both breakers side by side or use a 2 pole breaker which you would do anyway if you want a mixed voltage circuit like Rod is talking about.

I use multi-wire branch circuits to run 120v around the shop. By running 12-3 to around to each double box (not suggesting a home run for each unless you need that sort of capacity) you can wire 2 duplex outlets each with 20 amp capacity but without having to run two 12-3 wires.

You could also put GFCI breakers in as John mentioned which as long as your panel is close would work but it usually costs more than GFCI outlets.

Let me go into more detail and it'll help clarify my question.

First, my understanding of what Rod stated is that he runs a three wire (two hots and a neutral) multidrop circuit. That is, his three wires go to one box, then daisy chains to the next box, etc. At each box, he puts a 230V outlet and a 115V outlet. If this is not true, than my question is moot.

Next, the way a 115V GFCI works is by summing the current between the appropriate hot and the neutral. That is, at any instant, the current into the GFCI is equal to the current out of the GFCI. This means that the current in the hot is exactly equal and in an opposite direction to the current in the neutral. If someone touches the hot, some current flows to ground which means that it does not return through the neutral, and the two currents are not equal and opposite causing the GFCI to trip. So if you put a GFCI on two wires (one hot and the neutral) at one end of a 3 wire circuit and tail off of that, the GFCI won't work because the currents between the hot and the neutral will not be equal and opposite as soon as you use both sides of the circuit.

Given that, I have difficulty seeing how you could GFCI protect Rod's setup, except by putting a GFCI in each box on the 115V circuit.

It would not be possible to put a GFCI in the first box and chain the other outlets off that GFCI. At least, I don't see how it could be done.

Mike

[Jamie Schmitz]

Just a thought from my perspective, I am a fan of power strips as opposed to a bunch of outlets.They seem to space the cords more evenly without stacking and this helps with knowing what is what.Also putting in a lit light switch is a good thing for the main lights.
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[Van Huskey]

Let me go into more detail and it'll help clarify my question.

First, my understanding of what Rod stated is that he runs a three wire (two hots and a neutral) multidrop circuit. That is, his three wires go to one box, then daisy chains to the next box, etc. At each box, he puts a 230V outlet and a 115V outlet. If this is not true, than my question is moot.

Next, the way a 115V GFCI works is by summing the current between the appropriate hot and the neutral. That is, at any instant, the current into the GFCI is equal to the current out of the GFCI. This means that the current in the hot is exactly equal and in an opposite direction to the current in the neutral. If someone touches the hot, some current flows to ground which means that it does not return through the neutral, and the two currents are not equal and opposite causing the GFCI to trip. So if you put a GFCI on two wires (one hot and the neutral) at one end of a 3 wire circuit and tail off of that, the GFCI won't work because the currents between the hot and the neutral will not be equal and opposite as soon as you use both sides of the circuit.

Given that, I have difficulty seeing how you could GFCI protect Rod's setup, except by putting a GFCI in each box on the 115V circuit.

It would not be possible to put a GFCI in the first box and chain the other outlets off that GFCI. At least, I don't see how it could be done.

Mike

You are absolutely correct. There is no way that I know of to GFCI protect the type of circuit I now see it seems Rod was talking about without a GFCI outlet at each box for the 120V. I haven't wired a "dual voltage" circuit as he describes so I just defaulted to my set-up when it came time to answer, my bad.

[Mike Desch]

Another thought.
I ran 12-3 to most of my shop outlets. Then I can quickly change a 120V outlet to a 220V outlet, where ever I might need 'em.
Sure the 12-3 as a bit more pricey,but it sure gives me a lot of flexibility. Several places I used a single duplex that had a 115V outlet on the top and a 220V outlet on the bottom.
Lots of possibilities--and the advice in this thread should give you many different options to choose from.
at this point in your journey, spend just a little extra and plan for the future.

[Rod Sheridan]

If you need GFCI protection, and only want to run 3 wire cable, then it would require a GFCI receptacle in each box.

The other way is to come out of the panel as a multi-wire branch circuit, split into 2 wire 240V circuit, and then 2 X 2 wire 120V circuits each 120V circuit to have a main GFCI receptacle.

Regards, Rod.

[Brent DenHartog]

I ran a lot of dedicated circuits where I knew what I was going to place certain machinery, But on the wall where I wasn't sure what was going to end up there I did what Rod suggested and ran a single 12-3 wire to each box giving me the flexibility to switch between 220 and 110 at any location. I protected it using a 220V GFCI breaker. It was expensive (over $100) but it was the only way my electrician friend said I could do it. Seems like having 110V GFCI outlets as the first in the both chains would not work if any downstream outlets were used as 220V.