50 Amp Service Question

[Sehc]

It worries me that so many call power at the pedestal anything other than single phase. 120 or 240 volts, 15 or 50 amps doesn't mater, it is single phase. Even if the park is taking power from a three phase industrial feed, the pedestals are still single phase. If not, we are in big trouble.

Thanks John T

[oldjohnt]

5 minutes ago, Sehc said:

It worries me that so many call power at the pedestal anything other than single phase. 120 or 240 volts, 15 or 50 amps doesn't mater, it is single phase. Even if the park is taking power from a three phase industrial feed, the pedestals are still single phase. If not, we are in big trouble.

Thanks John T

 You're welcome Sehc, Indeed the RV parks total power distribution system may ??? (depends on several factors) utilize THREE PHASE as its primary incoming electrical energy source. In the many jurisdictions in which I practiced, the utility allowed ONLY one incoming service versus two or three different voltages and configurations as installing and maintaining multiples would have been expensive. A facility may be provided a single say 480 Volt Three Phase service by the utility provider and we had to install our own dry transformers to get any needed 120 or 208 or 240.

HOWEVER as you so clearly and correctly indicate, the power at an individual RV pedestal for supplying an RV  is SINGLE PHASE regardless if its derived from a three phase source at the parks main service entrance. In heavy industry three phase is, of course, THE way to go.

While the vast majority of RV parks are 240, if an RV there didn't require any full true heavy 240 volt loads (where 208 didn't suffice) but ONLY two legs of 120, heck two legs of 120 derived from a 208Y 120 Volt Three Phase Four Wire distribution would work  BUTTTTTTTTT as Jack and others pointed out with the advent of any heavy full 240 volt AC type loads 240 (NOT 208) becomes necessary BUT ITS STILL SINGLE PHASE !!!!!!!!!!!!

Fun chat for some of us sparkies, sorry to bore the other to tears lol

John T Now back to the RV and drafting a few Deeds to pay the bills...………….

[Darryl&Rita]

44 minutes ago, Sehc said:

It worries me that so many call power at the pedestal anything other than single phase. 

I gave up my "Don Quixote" attempt to convince the masses awhile back. About the same time as when I stopped correcting people for 110/220 volt.

[Lou Schneider]

On 9/24/2018 at 3:44 PM, NoDirectionHome said:

Are the two 120VAC legs of a 50 Amp RV sevice pylon in phase or 180 degrees out?

180 degrees out.  At the instant L1 is at +120 volts with respect to neutral, Line 2 is at -120 volts with 240 volts leg to leg.

That's for a single phase tap.  If the park is delivering two legs of a 3 phase Wye to the site, the same holds true (120 volts each leg to neutral)  except there will be a 120 degree vector from one leg to the other, not 180 degrees.  This means you'll only get 208 volts leg to leg.

[oldjohnt]

1 hour ago, Lou Schneider said:

except they'll be a 120 degree vector from one leg to the other, which means you'll only get 208 volts leg to leg.

That's right Lou, 120 x the Square Root of 3 = 207.84 IE so called 208 volts, piece of cake if you use vectors. We BOTH have explained how if one leg is at + 120 and the other at - 120 you get 240 across both legs, I think some are catching on and that's a good thing.

 John T

2 hours ago, Darryl&Rita said:

I gave up my "Don Quixote" attempt to convince the masses awhile back.

 You talkin about "To dream the impossible dream" lol  Take care Darryl& Rita

 John T

[Dutch_12078]

And that's why I prefer the term "split phase" when referring to standard 120/240 service.

[57becky]

On 9/27/2018 at 8:20 AM, Kirk Wood said:

As one who has been reading voltages for a very long time, I can't remember the last time that I saw 208V in an RV park. In addition, if the RV owner uses either of the major brand EMS systems they won't connect to a voltage more than 10% low.

We have stayed in the Park Sierra with our rig, and have the Progressive 50 amp hard wired EMS, and it works just fine.  It does not look at the leg to leg voltage, just the leg to neutral for both legs, so it is happy with either 240V or 208V, because it can't see them.

[Lou Schneider]

54 minutes ago, 57becky said:

We have stayed in the Park Sierra with our rig, and have the Progressive 50 amp hard wired EMS, and it works just fine.  It does not look at the leg to leg voltage, just the leg to neutral for both legs, so it is happy with either 240V or 208V, because it can't see them.

The Progressive EMS is just a voltage monitor and surge suppressor.  If you have a Load Management System that actually sheds or disables loads to keep the amperage draw within the supply limits, it will look at the leg-to-leg voltage, at least enough to verify that it isn't at zero (both legs in phase).  If it sees both legs are in phase it will assume you're plugged into a 30 amp outlet via an adapter and manage the loads accordingly.