30 AMP Connection at home

DrewE wrote:

RasMouSein wrote:
Haa I figured I wasn't crazy hehe, that it can be dangerous.
And when talking about a broken neutral,
it reminds me work, as a Lineman, a broken neutral going to the house is a very dangerous situation.
Give high amps to less resistive load, like tv's.

A broken neutral at a split phase supply (or, I suppose, at a three phase Y supply) is indeed bad news.

These days, though, a TV would probably not suffer any damage at all; most have international power supplies that work on just about any mains voltage from 100-240V.

Kind of cool what the Y will do without a wired neutral. It’s not unusual to use a virtual neutral, which is just the center of the Y without a neutral feed from the power source. Works fine for something like a motor or heater with the same load on each phase. But if you change the load on one phase, the line to neutral voltage on the others changes. This is the same thing that happens on an RV that loses neutral.

I worked on a setup that had neon bulbs as phase indicators. When manufacturing moved overseas, the bulbs started exhibiting a phenomenon where they gassed materials inside the bulb in storage, and when power was first applied they would arc internally which created a load on that phase. Burned up a lot of equipment before we figured it out.

RasMouSein wrote:
Haa I figured I wasn't crazy hehe, that it can be dangerous.
And when talking about a broken neutral,
it reminds me work, as a Lineman, a broken neutral going to the house is a very dangerous situation.
Give high amps to less resistive load, like tv's.

A broken neutral at a split phase supply (or, I suppose, at a three phase Y supply) is indeed bad news.

These days, though, a TV would probably not suffer any damage at all; most have international power supplies that work on just about any mains voltage from 100-240V.

Haa I figured I wasn't crazy hehe, that it can be dangerous.
And when talking about a broken neutral,
it reminds me work, as a Lineman, a broken neutral going to the house is a very dangerous situation.
Give high amps to less resistive load, like tv's.

jkwilson wrote:

RasMouSein wrote:


Well I stand corrected. Oups.
I saw and heard mistake where it was wired wrong and sent 240v in the rv appliance...

This is the big problem with a 50A circuit because this can happen. If the "service" neutral isn't connected, either through miswiring or a bad connection in the cable, then a heavy resistive load like an AC or water heater can cause the voltage of the neutral wire inside the RV to "move" toward that leg's voltage making the voltage of the other leg higher and sensitive stuff like electronics makes smoke.

That's why protection devices that can warn you, or better yet not connect the power to the RV, if the neutral is missing are so important.

That can happen to your nice 30A 120V campground pedestal too, if the open neutral is somewhere with the main campground feed. Granted, it's more likely to have a failure at your pedestal, in your power cord or transfer switch than the campground wiring but it happens.
It's is easier to reach higher incorrect voltages when you're the one pulling down on one side and just your site has the problem. The rest of the campground somewhat averages out both sides, even if the neutral were open.

jkwilson wrote:

RasMouSein wrote:


Well I stand corrected. Oups.
I saw and heard mistake where it was wired wrong and sent 240v in the rv appliance...

This is the big problem with a 50A circuit because this can happen. If the "service" neutral isn't connected, either through miswiring or a bad connection in the cable, then a heavy resistive load like an AC or water heater can cause the voltage of the neutral wire inside the RV to "move" toward that leg's voltage making the voltage of the other leg higher and sensitive stuff like electronics makes smoke.

That's why protection devices that can warn you, or better yet not connect the power to the RV, if the neutral is missing are so important.

Progressive Dynamics EMS to the rescue! :B
And no, I don’t work for them.

RasMouSein wrote:


Well I stand corrected. Oups.
I saw and heard mistake where it was wired wrong and sent 240v in the rv appliance...

This is the big problem with a 50A circuit because this can happen. If the "service" neutral isn't connected, either through miswiring or a bad connection in the cable, then a heavy resistive load like an AC or water heater can cause the voltage of the neutral wire inside the RV to "move" toward that leg's voltage making the voltage of the other leg higher and sensitive stuff like electronics makes smoke.

That's why protection devices that can warn you, or better yet not connect the power to the RV, if the neutral is missing are so important.

RasMouSein wrote:
Well I stand corrected. Oups.
I saw and heard mistake where it was wired wrong and sent 240v in the rv appliance...

That happens frequently when people (including electricians) wire up a 30A 3-pin RV receptacle to 240V. The plugs are similar, but not identical to the older 240V 3-wire appliances. 4-wire 240V is more common these days and with good reason.

jkwilson wrote:

RasMouSein wrote:

jkwilson wrote:

RasMouSein wrote:
Safety note people!!
Watch it when saying 240v outlet, for the rv one might be tempt to say 50amp 240v outlet, but in reality it's 50amp, 120v...
It by using both "legs" in the panel it's reduce the copper needs.
Only RV outlet are just for RV, welders dryers and stove, use 240v and have their own outlet.

Just like in your kitchen using the same neutral to the outlet, both receptacle are on different "leg". You can check with your multi meter and see that those outlet have "240v" but not really...

This isn't true. A 50A RV outlet is wired just like a standard dryer outlet. Nothing special about it at all and it is a 120/240V outlet.

You Don't get what I'm trying to point out...
The receptacle and plugs are different for a reason, because of the way it's wired in the RV.
I should have specified that.

But they aren't different in any way. An RV uses a standard NEMA 14-50R 50A 120/240V receptacle wired exactly like a dryer plug. It is the exact same receptacle and wiring used for some ranges and for charging electric vehicles. An RV with 50A service is wired exactly like a house, with some circuits on one leg and some on the other, and in some larger rigs using both legs for 240V appliances.

Well I stand corrected. Oups.
I saw and heard mistake where it was wired wrong and sent 240v in the rv appliance...

RasMouSein wrote:

jkwilson wrote:

RasMouSein wrote:
Safety note people!!
Watch it when saying 240v outlet, for the rv one might be tempt to say 50amp 240v outlet, but in reality it's 50amp, 120v...
It by using both "legs" in the panel it's reduce the copper needs.
Only RV outlet are just for RV, welders dryers and stove, use 240v and have their own outlet.

Just like in your kitchen using the same neutral to the outlet, both receptacle are on different "leg". You can check with your multi meter and see that those outlet have "240v" but not really...

This isn't true. A 50A RV outlet is wired just like a standard dryer outlet. Nothing special about it at all and it is a 120/240V outlet.

You Don't get what I'm trying to point out...
The receptacle and plugs are different for a reason, because of the way it's wired in the RV.
I should have specified that.

But they aren't different in any way. An RV uses a standard NEMA 14-50R 50A 120/240V receptacle wired exactly like a dryer plug. It is the exact same receptacle and wiring used for some ranges and for charging electric vehicles. An RV with 50A service is wired exactly like a house, with some circuits on one leg and some on the other, and in some larger rigs using both legs for 240V appliances.

jkwilson wrote:

RasMouSein wrote:
Safety note people!!
Watch it when saying 240v outlet, for the rv one might be tempt to say 50amp 240v outlet, but in reality it's 50amp, 120v...
It by using both "legs" in the panel it's reduce the copper needs.
Only RV outlet are just for RV, welders dryers and stove, use 240v and have their own outlet.

Just like in your kitchen using the same neutral to the outlet, both receptacle are on different "leg". You can check with your multi meter and see that those outlet have "240v" but not really...

This isn't true. A 50A RV outlet is wired just like a standard dryer outlet. Nothing special about it at all and it is a 120/240V outlet.

You Don't get what I'm trying to point out...
The receptacle and plugs are different for a reason, because of the way it's wired in the RV.
I should have specified that.