Current on a 12 gauge wire

[KennyG]

That's a clear way of stating it.

My question was, what if you wire 4 GFI's on one 12/3 MWBC, alternating them as you go, black leg, red leg, black leg, red leg, wired by the line terminals only, sharing the neutral as you go? Would that work?

Yes, it will work fine. I have that configuration in my pole barn/shop. The downside is that you pay extra for more GFIs, offsetting the saving in wire and complexity but on the plus side, you only lose one outlet if a GFI trips.

 

[LD1]

That's a clear way of stating it.

My question was, what if you wire 4 GFI's on one 12/3 MWBC, alternating them as you go, black leg, red leg, black leg, red leg, wired by the line terminals only, sharing the neutral as you go? Would that work?

Yep. Share the neutrals with whatever you want on the line side of the GFI.

The GFI only senses current on the load side. And a difference of more than 5ma between hot and neutral (on the load side) will trip it.

Load side can be either the load side screws that feed further outlets to be protected by the GFI (no neutral sharing off load side). Or it can be whatever is plugged into the GFI. Those are the two options for load.

Line side, do what you will.

 

[buickanddeere]

That's a clear way of stating it.

My question was, what if you wire 4 GFI's on one 12/3 MWBC, alternating them as you go, black leg, red leg, black leg, red leg, wired by the line terminals only, sharing the neutral as you go? Would that work?

What ?

 

[ray66v]

Thanks guys.

I didn't put any GFI's in my shop. They probably wouldn't work well. I had to put in hy-mag breakers, because some of my bigger 120v saws and grinders, can trip the standard 20 amp QO breakers on start up.

I'll put the GFI's in, when it's time to sell.

 

[ultrarunner]

If have GFCI's in the rentals but never in a home where I have lived... they were all older and predate GFCI and some predate grounding as in original 1922 service.

GFCI certainly have been the cause of service calls for the rentals... almost always it has been a tenant plugged in appliance but several times over the years I have had to replace the GFCI...

I also have a fair number of Hospital Grade GFCI at the Hospital... now over 20 years old and never an issue... they are all Hubble and were expensive even 20 years ago...

 

[Zerk]

We are building a home in the country and there are no building inspections or code requirements in this area. I?

Still bound by NEC. Just no local codes. Some counties or cities will be stricter than NEC. Which to me is BS. I am surpised being in TX you don't, they seem to like laws down there.

Less chance for problems if every circuit has it's own neutral. No shared neutral circuits. BTW, almost all circuits are designed to run at 80% max current. 15 amp breaker = 12 amps, 20 amp breaker = 16 amps.

Sort of. You derate for continuous loads. But that is a good rule of thumb.


Neutral sharing is not done as much anymore maybe, but nothing really wrong with it, if done by code. Think about a sub panel. That is one big shared neutral. I could see pull 12-3 to 4 pole with one 240 load, depending on the loads. I'd probably got to 10-3 though, but again depends on loads.



I would have the electrician explain if you are uncomfortable. Problem is you may be a big PIA, if you never understand it no matter how he explains it. Some people can't with electricty. They get all sketchy with details, than come on internet and it gets worse.

 

[Zerk]

If he's running (2) of the 12/3 wires you are good number of circuit wise, but I wouldn't let them do it in my house.

Why not?

 

[Zerk]

The water heater needs a 30 amp circuit on 10 gauge wire. That's 8 circuits for a modern kitchen.

Water heaters come in different size. This is why it is scary having people on the Internet give advice. You should not.

To do load calcs you work in watts. Then size wire and breakers.

A small water heater goes on 20 typically.


Also 8 circuits for a modern kitchen is silly.

 

[Zerk]

Six pages and I have read everyone of them :shocked: Lots of good information here though

we most be reading different threads.

 

[Zerk]

Great.

My first house, the power company used AL underground, from the transformer to the meter. I was lucky enough they used reasonable care when they did it. So, it never failed for the 23 years I was there either.

I'm not using it.

A great deal of wiring is aluminum. It is not used in branch circuits in home any more, except for ranges or sub panels. Massive amounts of aluminum are used else where.


Typically you increase by one wire size when running alum, instead of copper. You also put a coating under the lugs in the panel so they don't oxidize.


On one hand I say the codes get to crazy, on the other hand, I don't most people should do wiring, or talk about wiring.