Current on a 12 gauge wire

[GregbkH]

I was wiring y new house and asked an industrial electrician if I would be better off running 12 ga for lights instead of 14 ga for lights. He reached into his pocket and feigned throwing money on the ground. I got the picture. 14 ga. for lighting circuits after that.

It all depends on the load being placed on the circuit. The 12 ga. will give you 4 more amps to work with over the 14 ga.

 

[woody]

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

 

[GregbkH]

More power to ya! I can't find copper in anything over 4/0, and it is just darn near impossible to bend. That's why it is all alum in the bigger gages.

You must not be looking in the right places for the big copper. I've run miles of the big copper up to size 750 kcmil. Any electrical parts house should be able to get whatever size you want in any length you want and deliver it to your house.

 

[GregbkH]

With all of the problems the OP is having with his "electrician", Panel too high (max height to center of breaker handle = 6.5 feet max) ethernet and low voltage wires under the same staple as romex etc, it's time to cut him loose and hire a competent electrician and get the job done right.

 

[ray66v]

He said that is what power companies use and if they use it for hook up to a meter, why wouldn't it work for a service run. I got aluminum and worked fine for 12 years I owned the house.

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.

 

[bhstovall]

In the end, I think since you are the one footing the bill for this house, if you want it wired a certain way so it makes sense to you & it meets code it should be done the way you want it done. If it costs more, you are going to be the one who pays for it!

 

[buickanddeere]

We use copper on everyrhing that is not an overhead line . If it's big stuff such as 500MCM we just use a conduit bender to fit the cable to location.

 

[check]

Great thread - I learned some important things I didn't know before! (Like the need for using a full-sized breaker for 14/3 or 14/2 wire.)

 

[Gary Fowler]

Wire Fill is less so no need to up size conduit, material cost is less, less fill in the breaker box, less neutral on the neutral buss, fewer knockout in the panel box.

It really is quite common here...BUT the individual breakers must be full size and tied together.

The down side is a faulty appliance will cause a otherwise good circuit to trip since breakers are tied together.

This happened when a Dishwasher and Disposal were wired this way... disposal had a problem that also tripped the circuit to the refrigerator... homeowner simply thought the disposal was not working and not a clue power was cut off to the refrigerator.

This is why refrigerator/ freezers are supposed to be on a dedicated circuit. Don't let a $10 appliance ruin a $1000 worth of food because of a tripped circuit.

 

[buckeyefarmer]

This is why refrigerator/ freezers are supposed to be on a dedicated circuit. Don't let a $10 appliance ruin a $1000 worth of food because of a tripped circuit.

Required here, and it can't even be a duplex outlet.

 

[Larry Caldwell]

We are building a home in the country and there are no building inspections or code requirements in this area. I've told the builder that we want to at least meet all the code requirements even though there will not be any official inspections. So, here's the question: There are (2) romex 12/3 wire with ground running thru conduit (with water pipes) to the kitchen island. Supposedly there are (2) single pole 20 amp breakers tied into these wires somehow. I suspect the black wire is tied to one breaker and the red is tied to the other breaker. The primary current loads are:
- Dishwasher - calls for it's own 15 amp breaker
- 2 gallon hot water heater under the sink - probably a 1500 watt heating element (~12 amps)
- small appliance outlets - about 1500 watts for an electric skillet or waffle iron.
1st, I don't see how (2) 20 amp circuits can carry that load. I talked to the electrician and he says "not to worry, it's fine". (I've seen 12 gauge wire on a 30 amp breaker around here and I know that is NOT "fine".) It seems to me that the electrician is using a single 12 gauge neutral to carry the current from (2) 20 amp hot wires and the electrician tells me that 12 gauge can do that. :shocked: Nor do I understand how he's going to provide for the 3 circuits with 2 circuit breakers. I suppose that if we sequence the usage "properly" everything will work.

Am I behind the times? or am I missing something? I'm getting ready to tell the builder to stop work until this is fixed, but don't want to do that unless I'm right. Any thoughts?

Yes, your kitchen is thoroughly under-wired. You need separate circuits for the refrigerator, microwave, garbage disposal and dishwasher. You need a minimum of two 20-amp circuits for receptacles, and a separate 15 amp circuit for lighting. The receptacle circuits need to be on a GFI breaker, and a shared neutral will trip any GFI immediately. It will not work. The water heater needs a 30 amp circuit on 10 gauge wire. That's 8 circuits for a modern kitchen.

 

[LittleBill21]

. The receptacle circuits need to be on a GFI breaker, and a shared neutral will trip any GFI immediately. It will not work. .

This is nonsense. it most certainly works. if your gfci is tied in down stream of the shared neutral distribution. your entire panel is "shared neutral" anyways, mwbc doesn't change this.

 

[LD1]

Way too many people are severly mis informed about how both mwbc's and gfi's work

 

[aczlan]

Yes, your kitchen is thoroughly under-wired. You need separate circuits for the refrigerator, microwave, garbage disposal and dishwasher. You need a minimum of two 20-amp circuits for receptacles, and a separate 15 amp circuit for lighting. The receptacle circuits need to be on a GFI breaker, and a shared neutral will trip any GFI immediately. It will not work. The water heater needs a 30 amp circuit on 10 gauge wire. That's 8 circuits for a modern kitchen.

As has been said, you need either a 220V GFCI breaker, or two GFCI receptacles after you split off the neutral to the two directions.

Aaron Z

 

[LD1]

It's wired the same as any other GFI outlet. The GFI don't care what is shared on the neutral on the line side. GFI only senses neutral current on the load side.

You don't tie in the load side neutral to the line side neutral on a mwbc just like you wouldn't on a normal circuit.

 

[ray66v]

It's wired the same as any other GFI outlet. The GFI don't care what is shared on the neutral on the line side. GFI only senses neutral current on the load side.

You don't tie in the load side neutral to the line side neutral on a mwbc just like you wouldn't on a normal circuit.

Are you saying, you can successfully cascade GFI's on a mwbc, if you don't use the line terminals of the GFI's?

 

[buickanddeere]

As has been said, you need either a 220V GFCI breaker, or two GFCI receptacles after you split off the neutral to the two directions.

Aaron Z

A 2 pole GFCI breaker will trip when 120V loads are supplied from it.

 

[buickanddeere]

How does anyone imagine that a GFCI receptacle/breaker supplying a fridge makes the world a better place?
How does anyone think that sharing a fridge circuit and breaker with another load makes the world a better place ?

 

[LD1]

Are you saying, you can successfully cascade GFI's on a mwbc, if you don't use the line terminals of the GFI's?

Not sure what you are asking.

If you want to use a MWBC to make TWO circuits that share a neutral, and you want BOTH of those circuits GFI protected, You run the Black and shared white wire from MWBC to the line terminals of the 1st GFI. You run the Red and the shared white to the other GFI.

From the GFI's, you wire everything downstream off the load side of the GFI's, just as you would with a normal circuit. From the GFI onward, is 12/2 wire and NO neutral sharing.

 

[ray66v]

Not sure what you are asking.

If you want to use a MWBC to make TWO circuits that share a neutral, and you want BOTH of those circuits GFI protected, You run the Black and shared white wire from MWBC to the line terminals of the 1st GFI. You run the Red and the shared white to the other GFI.

From the GFI's, you wire everything downstream off the load side of the GFI's, just as you would with a normal circuit. From the GFI onward, is 12/2 wire and NO neutral sharing.

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?