50 Amp wiring

Heisenberg wrote:
#8 wire is 40 amps according to the NEC.

75degC thwn (most commonly used)is 50A.

#8 wire is 40 amps according to the NEC.

Wow, all these arguments are pretty much over semantics.

Again, proper terminology would be:
50A, 240v, 1 phase, 3 wire circuit to a 14-50R (receptacle)

To be more specific:
Provide 50A/2p circuit breaker with 3#8, #10gnd.-1"C. to a 14-50R receptacle.
Connect complete.

The term (120v) should never be mentioned as it is inferred and will only confuse the issue. The electrician does not care how the receptacle will be used, only what he needs to provide. There is no such thing as a 50A/2p 120v breaker, it will always be referred to as 240v.

Larryect wrote:
Yep. And earlier I believe it was stated if an electricain calls it 240 volts - Don't hire him.

Well the problem is, it IS a 240 volt circuit and that is in fact what it needs to be. Exactly for the reason pointed out. If you don't have 240 volt, your neutral can be called upon to carry TWICE its rated amperage - with NO protection.

Yes Larry it was said by some one who does not understand that if an Electrician calls it 240 volt do not hire him.. I took that poster to task for saying it.. It is after all 240 (Well 120/240) volt service, SAME EXACTLY as your house.

The danger with calling it 120 volt is this: The proper way to wire the outlet, I will forget the safety ground for the moment (It is of course wired to safety ground in all examples)

L-1 N L-2 This is proper

if some idiot wires it either
L-1 N L-1
Or
L-2 N L-2

You now have 120 volts on each leg, IN most motor homes without energy managers everything works, BUT, and this is one nasty BUT.

The Neutral is now hauling as much a 100 amps.. Now 50 it can do, 60 likely won't bother it (only 20% over rating) but 100, it's going to get warm, hot even, and if it gets hot enough the FIRE DEPARTMENT comes calling.. And frankly, I do not wish to do business with those nice folks if I can avoid it.

Thus I think of the 50 amp service as 120/240 and check to make sure it is that.. Cause if it's 120/120 with zero volts side to side..

Well.. I have heard of parks wired that way.. And this is not a good thing. Not a good thing at all.

Bumpyroad wrote:

Larryect wrote:

Bumpyroad wrote:
so people here are trying to tell me that 50 amp service is only 20 amps more than 30 amp service, and not 70 amps more? that certainly isn't what posts have said over the years. and I don't see why the fact that the neutral balances out to zero really affects this situation, other than size needed of the neutral wire.
bumpy

It is 50 amps at 240 volts or 12,000 watts vs 30 amps at 120 volts or 3,600 watts. Lots of difference. Just never referred to as 100 amps.

The neutral only needs to carry the imbalance of the two hot legs when it is wired properly. The neutral is always sized to match the hot legs. If the hot legs are of the same phase, there would not be opposite phases to balance and the neutral would be required to carry everything both hot legs are carrying. This creates a very dangerous situation when trying to say this is strictly a 120v connection when it should be in fact a 240 connection.

you have stated exactly what I have read here in the past. don't know why some folks here are trying to confuse things.
bumpy

It can be confusing if you ignore the voltage side of things. At the receptacle it is 50 amp service at 240 Volts. It is when the coach distribution panel breaks it down into the 120V legs that you get 100 amps aggregate. That is why they call the RECEPTICLE 50 amp service. The Electrician is installing the receptacle, not the coach systems. That's why when someone said to fire the electrician if they called it a 240V receptacle, they were giving really poor advice.

The key is are the 2 120v feeds in the circuit in phase with each other or out of phase. They must be out of phase to balance the load on the neutral. If you read zero volts between the two hot wires it is wired wrong, they are both a phase or b phase. You must be able to read 240 volts between the hot wires. The neutral is a center tap on the transformer load side. If the two 120 v hots originate on the same side of the center tap you have an unbalanced circuit. Dangerous. Period.

If some of you folks are electricians, you need to go back to class and I'll do my own wiring (and I did my own, thank goodness). I'm not and electrician but I know how it is supposed to be wired. Many of you are saying the same thing but saying that the other is wrong.

You can call it whatever you want but you had better be supplying only 120 volts to your motorhome receptacle outlets and appliances. You should have 12,000 watts available. To make it more simple, a 50-amp service has 4 wires with two 120-volt HOT feeds,,,,,,,,,, like Dougrainer said.

Dennis, 6/3 w/ground is a cable term meaning 3 current carrying conductors #6 gage and a ground which is de-rated one size #8 gage.

Larryect, you sir are correct.

Larryect wrote:

Bumpyroad wrote:
so people here are trying to tell me that 50 amp service is only 20 amps more than 30 amp service, and not 70 amps more? that certainly isn't what posts have said over the years. and I don't see why the fact that the neutral balances out to zero really affects this situation, other than size needed of the neutral wire.
bumpy

It is 50 amps at 240 volts or 12,000 watts vs 30 amps at 120 volts or 3,600 watts. Lots of difference. Just never referred to as 100 amps.

The neutral only needs to carry the imbalance of the two hot legs when it is wired properly. The neutral is always sized to match the hot legs. If the hot legs are of the same phase, there would not be opposite phases to balance and the neutral would be required to carry everything both hot legs are carrying. This creates a very dangerous situation when trying to say this is strictly a 120v connection when it should be in fact a 240 connection.

you have stated exactly what I have read here in the past. don't know why some folks here are trying to confuse things.
bumpy

Bumpyroad wrote:
so people here are trying to tell me that 50 amp service is only 20 amps more than 30 amp service, and not 70 amps more? that certainly isn't what posts have said over the years. and I don't see why the fact that the neutral balances out to zero really affects this situation, other than size needed of the neutral wire.
bumpy

It is 50 amps at 240 volts or 12,000 watts vs 30 amps at 120 volts or 3,600 watts. Lots of difference. Just never referred to as 100 amps.

The neutral only needs to carry the imbalance of the two hot legs when it is wired properly. The neutral is always sized to match the hot legs. If the hot legs are of the same phase, there would not be opposite phases to balance and the neutral would be required to carry everything both hot legs are carrying. This creates a very dangerous situation when trying to say this is strictly a 120v connection when it should be in fact a 240 connection.