Using 220V legs for 120V circuits...

Long story short, I added a 30 amp, double pole GFCI to my electrical panel.

I am now wiring up each leg to power 20 amp, 120V circuits.

What I don't understand is how to size the neutral wire for my 120V circuits.

Does my neutral wire need to be 10AWG?

Can I share this neutral wire between the several of my receptacles?

I know that 220V sometimes uses only 3 wires and really doesn't have to have a neutral wire because of different "phases." But yeah, I don't quite know what that means or how it applies to my situation.

Normally, when running 20 amp, 120V circuits each has it's own neutral wire. I know 220V is different, but since I'm running several 120V circuits off of it, I'm not sure how to proceed.

I can provide more info/photos of what I am doing if needed. Thanks a lot for the help guys.

If you have 120v circuits branched off the 30 amp gfi, you will need circuit protection on them anyway. So all the wires past the 20 amp breaker can be 12 awg.
Is there any 240v equipment running off that gfi? Why did you not just add 2 20amp gfi's?

I am using fuses to protect the 20 amp wires.

I'm not using 220v for anything. Long story why I'm doing it this way. But I'm using the double pole gfci to power keggles with two 120v elements in each one.

So each element plugs into a 20 amp receptacle and I'll only be using 20 amps from each leg at a time. I'm building a control panel with DPST relays to turn both elements on with one switch.

What I don't understand is how to properly run neutral wires for my outlets. I have s total of 7 receptacles what with pumps and fans, etc.

So does one 10awg neutral wire cover me? Or do I need a neutral wire for each 120v leg?

You can share the neutral between the two legs, they are 180 degrees out of phase.

I'm sure your neutrals can be sized identical to your hots. So if you've got your hot wires fused for 20 amp, then your hots (past the fuse), and neutrals and grounds from the equipment can be 12 awg. Still sounds super weird why you wouldn't have 2 20 amp gfi's.

mux said:

You can share the neutral between the two legs, they are 180 degrees out of phase.

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So one 12AWG wire handles both legs? Or do I need a 10AWG neutral wire?

I ran 12AWG without thinking since all the receptacles will be on 20 amp fuses.

As for why I did if this way, I'll fill you in tomorrow.

Use the same gauge neutral as hot from the circuit breaker to the point all your neutrals are tied together.

Dgonza9 said:

So one 12AWG wire handles both legs? Or do I need a 10AWG neutral wire?

I ran 12AWG without thinking since all the receptacles will be on 20 amp fuses.

As for why I did if this way, I'll fill you in tomorrow.

Click to expand...

What type of receptacle is the control panel tying into?

mux said:

What type of receptacle is the control panel tying into?

Click to expand...

Basically, I'm running wires from the relays to 20 amp receptacles, 7 total. 2 BK elements, 2HLT elements, RIMS, 2 pumps and a fan. I'm using DPST relays to throw both elements on with a single switch and using fuses to protect the 12 AWG wires.

It is a weird thing to do, but here's why I am doing it this way. I originally went electric with 2 120V elements in a kettle. My panel was pretty full and I knew nothing about 220V or installing a circuit breaker. I was using a two vessel, Brutus 20 system and I would switch the elements on using using switched, 20 amp, GFCI receptacles. I had the circuits already installed.

This was fine until I started adding to the system. I added a HLT, so that became two more switches, then I added a RIMS, then another pump, plus a ventilation fan. So all of a sudden I had switches everywhere. Along the way I learned how to add CB to my panel.

Now I'm making a control panel to simplify things. I'm more comfortable with electrical, so I put in a 30 amp, 2 pole GFCI breaker. I didn't use 220V elements because my kegs have two holes in them, plus, then I'd have to redo the cords to each keg, etc. But with 220V power I can always do that later if I wanted to.

I ran each leg to a different element. So I can turn both elements on without drawing 40 amps off of one leg. I'm a little concerned about the RIMS tube, though. I'll need to use the RIMS and HLT at the same time. That should pull about 27.3 amps, plus the pump, which is 1.4 amps.

So at peak, I might be pulling 28.7 amps during the mash. If the breaker trips, I'll run a separate line for the RIMS Tube.

Size your neutral wires the same as the hot wires. #10 from the 30 amp breaker to the control panel buss bar and #12 to each element from that same buss bar.

yjfun said:

Size your neutral wires the same as the hot wires. #10 from the 30 amp breaker to the control panel buss bar and #12 to each element from that same buss bar.

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This sounds right to me but you would want to put a 20A fuse to protect the #12 wires, and an appropriate sized fuse for whichever size wire you use downstream from the 30A CB.

I have a 50A GFCI breaker in my control box and fuses inline for all the wire runs in my panel less than #6. They can be simple inline fuses.

Yes you do need to fuse the hot wires if they are downsized but the neutrals should never have a fuse on them. You don't want the neutral fuse to blow and not the hot wire fuse or you may become the only path to ground.

I'm done with the panel. I wet tested it last night and ran the HLT, RIMS and pump together. Can't be too much below the 30 amp limit, but it worked fine.

Thanks.

To answer your, or future, questions regarding the shared neutral, this is how it works. Yes, for a 240 circuit you only need 1 neutral leaving the main box. When both hot legs are working, then when one is "pushing" the EMF, the other is pulling. (they both go back and forth between pushing and pulling in an A/C system) If each is working at a 20A load, then the one pushing is equal to the one "Pulling" and the neutral that runs to the main box is carrying zero load. However, if there is a difference, then the neutral line going to the main circuit carries that difference. If one leg is operating at 30A and the other not at all, then the neutral going back to the main circuit panel must be 30A to accommodate this load.