50 Amp Electrical hookup

found this illustration that may be helpful to you
http://www.janeandjohn.org/docs/50ampRVoutletInstallation.pdf

wa8yxm wrote:
Yes a 50 amp outlet can be either converted or adapted to RV use provided it is a proper 4 WIRE outlet..

What is proper
Two hots and a neutral ALL THE SAME SIZE and a safety ground (may be a size or two smaller)

208/250 volts

3 Phase power is indicated by the 208 volt label.. This means the phases are not in sync (single phase split) but two phases 120 degrees apart.

Since generally speaking there is nothing in your RV that needs 240 volts. and clearly nothing in stgorag at all.. this will NOT be a problem.

Although I'm mostly using the place for storage, it's actually a shop so that's why it has the existing 240 outlet. I do have a CNC machine that runs on 240 volt power, so I'll eventually take it to this shop to use. Only problem is the existing 240 outlet is no where near where I'd want to put the CNC since it would block the motorhome. So I'll end up putting in a new 240 outlet for it anyway, and it has a different type of plug too.

msmith1199 wrote:
I just moved my motorhome to a new indoor storage location that has a dedicated electrical panel that I'm allowed to modify. The unit has several 15 amp plugs already installed. It has one 50 AMP I think 250 volt outlet, but the circuit breaker is labeled as 208 volt. I'm not an electrician so I don't know which it is.

So the question, can that 250 volt outlet be converted to a 50 AMP RV outlet? I know the 50 amp RV outlet has two 120 volt legs. Should this existing 208 or 240 or 250 volt (I guess I'll have to figure that out for sure) have the correct wiring for the RV outlet? It would be nice to have as that will allow me to run the A/C units while in storage as I plan on doing some work on it while indoors.

This is a commercial voltage and they're using two legs of a 3 phase secondary with a common 480vac primary.
As long as they pulled the neutral and ground in and since most RV's don't use 240vac for anything, you should be fine, as each leg to neutral or ground will read 120vac. Reason being is that these 208 hot legs are 120 degrees out of phase and mathematically, 208vac divided by the square root of 3 = 120vac.
If you were using 240, like for a range, more than likely, it just wouldn't get as hot as it should.

The difference being the center tap neutral on a single phase transformer. The phase angle is different and RMS measures the different voltage at that time.

We do not have to worry because all we need are two out of phase 110 volt legs for our energy management system to recognize.

Black Red Blue will work. We need the Black Red or the Red Blue or even the Blue Black and our 50A service will work perfectly.

If it is Brown Orange Purple get away from it.

Yes a 50 amp outlet can be either converted or adapted to RV use provided it is a proper 4 WIRE outlet..

What is proper
Two hots and a neutral ALL THE SAME SIZE and a safety ground (may be a size or two smaller)

208/250 volts

3 Phase power is indicated by the 208 volt label.. This means the phases are not in sync (single phase split) but two phases 120 degrees apart.

Since generally speaking there is nothing in your RV that needs 240 volts. and clearly nothing in stgorag at all.. this will NOT be a problem.

DrewE wrote:
I would suspect it's 208 volts and you have two phases of a three phase system going to it. The only way to know for sure is to measure the voltage. It really makes no practical difference whether you have 208 or 240 volts between the legs as far as the RV is concerned, provided of course you have a properly installed outlet otherwise. Both would be permitted in campgrounds (and which one you find would depend on the nature of the electrical service at the campground).

Whether the receptacle can be converted as-is to an RV outlet or not depends on what wires are run to it. My hunch is that you would need to run an additional (neutral) wire, which may be pretty straightforward or may be rather difficult, depending on the circumstances.

It's only about two feet from the panel so adding another wire may not be hard, depending on how much room is left in the conduit. I could probably pull the three out pretty easily and pull all four together if I needed too. Don't I also need to change the breaker?

phase angle .... it will be ok! You will have 110V on each leg.

I would suspect it's 208 volts and you have two phases of a three phase system going to it. The only way to know for sure is to measure the voltage. It really makes no practical difference whether you have 208 or 240 volts between the legs as far as the RV is concerned, provided of course you have a properly installed outlet otherwise. Both would be permitted in campgrounds (and which one you find would depend on the nature of the electrical service at the campground).

Whether the receptacle can be converted as-is to an RV outlet or not depends on what wires are run to it. My hunch is that you would need to run an additional (neutral) wire, which may be pretty straightforward or may be rather difficult, depending on the circumstances.

msmith1199 wrote:
On that link the existing outlet is the NEMA 6-50R that is posted. Note on the face it says 250 volts which is where I got the 250 number from in my original question. The single pole breaker that is in the box has "208 Volt Outlet" written on it. So I assume it's 240 volts? So what I get from this link is the current outlet is probably three wire versus the four wire that I need for the RV outlet.

No, you should assume it is 208 and is very common in commercial power.

Electrician just needs to pull a neutral and swap the 6-50 for a 14-50 and you are all set.

250 is just the maximum rating of the connector.

Busskipper wrote:

msmith1199 wrote:
I just moved my motorhome to a new indoor storage location that has a dedicated electrical panel that I'm allowed to modify. The unit has several 15 amp plugs already installed. It has one 50 AMP I think 250 volt outlet, but the circuit breaker is labeled as 208 volt. I'm not an electrician so I don't know which it is.

So the question, can that 250 volt outlet be converted to a 50 AMP RV outlet? I know the 50 amp RV outlet has two 120 volt legs. Should this existing 208 or 240 or 250 volt (I guess I'll have to figure that out for sure) have the correct wiring for the RV outlet? It would be nice to have as that will allow me to run the A/C units while in storage as I plan on doing some work on it while indoors.

Read and if you understand Install.

This is the best I can do - I'm 2,700 miles away - If in doubt just call an electrician, really simple.

Best of Luck,

On that link the existing outlet is the NEMA 6-50R that is posted. Note on the face it says 250 volts which is where I got the 250 number from in my original question. The single pole breaker that is in the box has "208 Volt Outlet" written on it. So I assume it's 240 volts? So what I get from this link is the current outlet is probably three wire versus the four wire that I need for the RV outlet.