Been reading post on electrical

[Tiger8r]

And was wondering if my thinking was right.Are Rv park pedistals that have 50, 30, & 20 amp services in one pedistals wired with 6 gauge wire for the 50 amp breaker, then a #10 jumper from one 50 amp leg to the 30 amp and another jumper from the second 50 amp leg to the 20 amp outlet. The other option would be to run a complete circuit to each outlet with hot(s), neutral and ground.

[Tiger8r]

Thanks to all for your replies did not know about the loop system will need to read up on that.

[Homer1]

I wish I had the electrical savvy some of you guys have.

[wa8yxm]

The standard pedistal is a "Distribution panel" Single 240 volt feed goes to bus bars inside the pedistal

Twin 50 amp breakers feed the 50 amp outlet off the bus bars

20 and 30 amp breakers feed the 20 and 30 amp outlets.. usually one per bus bar (That is one per leg).

Just like a circuit breaker box at your house feeds all the circuits in teh house.. Same inside save no main breaker. (it is a "Sub Panel").

[myredracer]

Nowadays pedestals are loop fed from one to the next with heavy gauge cable (or wires in conduit). Pedestals are rated 100, 125 & 200 amps. A CG will have one or more pad-mounted transformers around the property to supply 120/240 volts to the pedestals and have a high voltage primary connection. The pad-mounted transformer will contain circuit breakers to supply each run of pedestals.

The pedestals are similar in concept to a panel in a house. They have a mains rating (up to 200 amps) and breakers in them. The breakers and receptacles are pre-wired by the pedestal manufacturer. Pedestals can accept up to 350 MCM gauge wire which is good for up to 350 amps. Although a pedestal is rated 200 amps, the cable between can be oversized for voltage drop.

There are maybe 1/2 dozen manufacturers of pedestals. Here is brochure info. from Milbank for example: Milbank RV products and includes RV park transformers.

In the olden days, a CG would have panels distributed around the property with a 30 amp (120 volt) cable to each site, or 50 amp cable (120/240 volt) to each site. If you go far enough back in time, the code didn't require 50 amp pedestals. Loop feeding pedestals is much more efficient and results in lower voltage drop at sites too.

Every pedestal in a CG must have a 20 amp receptacle by code. A CG must have a min. of only 20 percent of the pedestals at 50 amps and 70 percent at 30 amps. 20 amp recepts. are not included in load calculations. 50 amp pedestals have a required demand of 9600 watts and 30 amps is 3600 watts. As mentioned above, multiple pedestals on a run are allowed to have a derating factor applied for a feeder cable as in NEC table 551.73 and 7 pedestals would be at 55 percent. NEC demand factors and pedestal requirements are covered in article 551.71 through 551.73 and can be found here.

Unfortunately, the NEC is waaay behind on the number of 50 amp RVs out there now and finding a 50 amp pedestal can be difficult unless a CG has gone above the min. code requirements. I see lots of folks with 50 amp RVs plugged into a 30 amp pedestal all the time.

[BB_TX]

I would doubt they would go to the costs of running 3 complete full rated circuits to every pedestal. And there would really be no good reason to justify that additional cost of wiring.

Next time you are at an RV park, turn off the 50 amp breaker, turn on the 30 amp breaker, and see if the 30 has power. Same for the 20.

[time2roll]

Usually connected on a 200 or 400 amp shared loop using much larger wire.

NEC allows derating so about 7 pedestals can be on 200 amp.

Breaker to outlet will be #8, #10, #12 wire.

[westend]

Pedestals I've seen all have circuit protection between line voltage and receptacle. Yes, they may all have been fed from a single 240 V circuit.