Running 50 amp circuit Need Expertise

[Kaadk]

Originally Posted by Herk7769

So from the "looks" of the incoming wires, it seems to me to be correctly sized for 50 amps. Since the 20 amp breaker is upstream from the 50 amp breaker in this box, if both are used to capacity, 70 amps would be on the L2 and Neutral feed wires.

Seems a recipe for eventual burned up wires...

Not if it properly has a matching 50A breaker at the main panel. If so, as 5 Picker mentioned, it would pop that breaker.

[5picker]

Originally Posted by Kaadk

Not if it properly has a matching 50A breaker at the main panel. If so, as 5 Picker mentioned, it would pop that breaker.

True.

Boy... we've derailed this one.

Apologies to the OP...but... often times the best discussions are derailments of the original post.

[Kaadk]

Originally Posted by 5picker

And once that L1/L2 same phase load reaches 50a, the breaker pops and no harm to the neutral. But we speculate...

Correct, if you try to pull more than 50a through the hot, it'll pop. The concern though is if you only had that more than 50 on the neutral. As I said, it's doubtful (more like improbable), because it would have to take some serious miswiring to achieve this. So much so it would almost have to intentionally be done.

Mixing up phases though, is possible and does have consequences. Years ago I worked for a manufacturer making Machine Vision systems used for quality control in automotive lines. We had a 3 phase feed into our building, supplying all our systems. The hydro company, in their infinite wisdom, needed to do some work on the lines and decided it was ok to shift our L3 feed to be in phase with L2 while they did their work without informing us. I was pretty green at the time, so I don't remember all the details, but I do remember that a bunch of our systems were down for days while our engineers fixed them. And our industrial robot we had for testing had to be replaced.

[Waterops1]

Originally Posted by Herk7769

Yes indeed. That is one of the best ways to find out if you can "use" the Duplex outlet for an extra kick if there is only a 30 amp and a duplex.

If you trip the 30 amp off and it kills the duplex you will know for sure you won't gain anything.


Speaking of which; what is wrong with THIS picture …

Wired it using single-pole circuit breakers instead of a double-pole for the 50 Ampere receptacle. Someone/somewhere that may be allowed but I would not do it that way.

[Herk7769]

Originally Posted by Waterops1

Wired it using single-pole circuit breakers instead of a double-pole for the 50 Ampere receptacle. Someone/somewhere that may be allowed but I would not do it that way.

You missed that they were also two 30 amp breakers.

My guess the campground found a bad 50 amp breaker and made a "permanent temporary fix" using two on hand 30 amp breakers.

The fact they were still there to be found by a camper just shows how permanent a temporary fix can be.

[cavie]

Originally Posted by Brewhedd

The difference between say a residential stove and your rv is the stove is wired with 2 hots and ground. The rv needs 2 hots, a neutral and ground. While the full 220 is applied to the stove the rv is 2 120 circuits.

Since about 1990. There is no difference in your house 220 range outlet and your trailer 220 volt 50 amps. 2 hots 1 neutral and a ground.

[cavie]

Originally Posted by formerFR

SO incorrect!!!

50amp RV service is a double-pole 50amp TWO hot lines to the coach, for a total of 100amps.... this is why you need a PROFESSIONAL electrician, don't let anyone on this forum 'give' you or him 'wiring' advice!


Once you get it installed, though, you realize how much more power 50amp service is over typical 30amp rv service is... it's 70amps more!

enjoy

I am a 45 year Master Electrician/Electric inspector. Why can't I give electrical wiring advice?

[cavie]

Originally Posted by formerFR

don't rely on this forum for professional electrical advise, as your own electrician is the final word on what you need, HE's the one wiring it!....if he's never 'done it' before, seek another electrician. It's not complicated.

Not even from a retired 45-year Licensed master electrician??

[cavie]

Originally Posted by D W

These days, many of your high-end ranges require the NEMA 14-50 configuration as opposed to the standard 3 prong NEMA 10-50.

The National Electric Code required 4 wire range and circuits for over 25 years. All new ranges and dryers come with 4 wire options. 3 wire cords can be used to fit older wiring.

[cavie]

Originally Posted by b bob

Herk, if the pedestal is wired "downstream" as you described, would the 50 amp pedistal breaker need to be on for the 30 amp and/or duplex outlets to be powered?

No, the 30 or the 20 amp breakers do not require the 50 amp to be on. Each one is on the same busbar feeding separate outlets. Unless it was wired by a jackleg non-electrician.

[Larry-NC]

Originally Posted by RVBuff

Question for Herk or wmtire...This may be just idle curiosity, but you've raised a question in my mind. Suppose you are in a 50-amp RV and using two interconnected devices...say a desktop computer physically connected to a printer. And say the computer is plugged into an outlet served by L1, while the printer is plugged into an L2 outlet. Is there any potential hazard from having the devices on out-of-phase "hots"? Would the neutral side in the two devices be out of phase, thus yielding a 120-volt potential across them?

Interesting question...but only a few of us will appreciate it.
First of all, you are confusing Neutral and Ground. You are posing the case of two metal-cased appliances with three wire cords connected to different phases and wondering whether the shield of a shielded cable, grounded at both ends will carry current because of different potentials of the neutral wire. But it doesn't work that way. The neutral is not involved. The connection between devices is Ground, not Neutral. And the ground is the same potential for both.

It is true that the Neutral wire is roughly Ground potential but they are not the same. There is only one point in the system where the neutral and ground are tied together--and this is the reason for it.

Larry

[cavie]

Originally Posted by Herk7769

In order to save some money he might want to run "240 volt" with no neutral; just a black L1, red L2, and safety green. Most 220 volt appliances, like your water heater will work just fine with those 3 wires. The camper will not.

Print the attachment out for your electrician. Full credit to NOSHOCKZONE.ORG for the illustration!

Oh and BTW, in the box below, the 20 amp GFCI duplex is wired "upstream" of the 50 amp breaker (by that buss tie metal clip). The 50 amp breaker's position does not effect the operation of the 20 amp circuit in this case.

You only do this to run strictly 220-volt appliances and motors. 120 requires a neutral, so I don't understand your statement save some money.

[cavie]

Originally Posted by Herk7769

You missed that they were also two 30 amp breakers.

My guess the campground found a bad 50 amp breaker and made a "permanent temporary fix" using two on hand 30 amp breakers.

The fact they were still there to be found by a camper just shows how permanent a temporary fix can be.

Thoses are SQ D 30 amp breakers. there are holes in the handles. They make a handle tie to place between the handles to make it a legal 2 pole breaker. I have installed a cut off 12D nail to get by in a pinch

[Herk7769]

Originally Posted by cavie

You only do this to run strictly 220-volt appliances and motors. 120 requires a neutral, so I don't understand your statement save some money.

Electricians may not understand that and only run 2 wire w/ground vice 3 wire w/ground. Figuring a lower quote based on the cheaper wire.

[cavie]

Originally Posted by Herk7769

Electricians may not understand that and only run 2 wire w/ground vice 3 wire w/ground. Figuring a lower quote based on the cheaper wire.

if a real electrician sees a 50 amp 4 wire cord he will know what to do with it. If a real electrician sees a 30 amp 3 wire cord he will know what to do with it because he knows he needs a ground and a neutral. They just lose the thought when they see 30 amp cords and forget it's not 220. Remind them it is 30 amp 120 volts 3 wire. They will understand. If they cross wire the hot and neutral they are not an electrician.

[BandJCarm]

This is what I gave the electrician when he (a 36 year master electrician) couldn't figure it out. Not sure this works..........but if so it's a good document.

[Herk7769]

Originally Posted by BandJCarm

This is what I gave the electrician when he (a 36 year master electrician) couldn't figure it out. Not sure this works..........but if so it's a good document.

That will do; that will do ...

[cavie]

Originally Posted by BandJCarm

This is what I gave the electrician when he (a 36 year master electrician) couldn't figure it out. Not sure this works..........but if so it's a good document.

he must have been wiring out houses for 36 years.

[BandJCarm]

Originally Posted by cavie

he must have been wiring out houses for 36 years.

I dunno what he did, but he had one 50 amp breaker and it didn't work and he ended up with two in the breaker box to make it work.

My knowledge of electricity is that NON LABELED switch on the wall about chest high. I have no idea why they don't label the two sides OFF and ON, but they don't.

[cavie]

Originally Posted by BandJCarm

I dunno what he did, but he had one 50 amp breaker and it didn't work and he ended up with two in the breaker box to make it work.

My knowledge of electricity is that NON LABELED switch on the wall about chest high. I have no idea why they don't label the two sides OFF and ON, but they don't.

If you're talking about one in your house that is a 3-way switching system. It requires 2 switches. The on and off, up and down changes depending on what position the other switch is in. I pray they never install any in an RV. I'll have to stop reading.