Setting up shore power

[rogercwhite]

Hi,

New to the travel trailer world and am setting up my trailer as a "destination" camper at a partially improved campsite. We have city water, a sceptic system and I have power to an entry pole. I am going to have an electrician run power from the entry pole about 160 feet to 2 gravel pads that a buddy and I have made, and have asked him to hook up a standard 50A/30A/20AGFCI RV pedestal at each pad. I have solicited 3 bids, and they're very close in price, but I don't know what I don't know....and I know that I've always paid someone to deal with electricity because I don't want to get fried. Now I'm more concerned about frying my trailer... Two bids are using 4 strand 4/0-4/0-4/0-2/0 and one bid proposed 3 strand 4/0-4/0-2/0 with a ground rod at the trailer. I'm using a Progressive Industries 50A surge protector at the pedestal of my trailer. Questions:

1. Which type of wire (4 or 3 strand) do I want and why?

2. Even with a grounding wire in the supply line, do I need to run a grounding rod from the trailer frame?

Thanks in advance!

[PappaJohn]

I am not a licensed electrician but 4/0 cable is rather excessive. Are you sure they are not recommending #4 wire?

The number of strands per conductor is not an issue for you. More strands make the wire more flexible and easier to install. The current carrying capability is the same.

Like I said, I am not a licensed electrician but I don’t understand the need for the ground rod at the pedestal but there might be some special code requirements that I am not aware of.

[rogercwhite]

I am not a licensed electrician but 4/0 cable is rather excessive. Are you sure they are not recommending #4 wire?

I was told I needed either a ground wire in the bundle or a ground at the trailer, but I'm an electrical idiot. The service at the pole is 200 amps, which will initially cover just 2 campers with growth for a couple more, and it's a fairly long run. Those were the cable sizes on the estimates.

Cheaper is better for me, with the caveat I don't ever want to fry my camper. I'm building out that place to be my respite, and I don't want issues from doing something wrong.

Thanks!

[fez111]

I am not a licensed electrician but 4/0 cable is rather excessive....

I am a licensed electrician and I can unequivocally say that 4/0 Aluminum is what I use for 200 amp service/entrance wiring to a home. According to National Electrical Code (NEC), 4/0, 4/0, 4/0, 2/0 copper cable is good for 260 Amps per phase!

There are new rules for installing power pedestals for RV's, including the requirement for a 30 Amp-220 volt receptacle and a GFI-protected 20 amp-120 volt outlet.

Your electrician 'may' have included a deration factor for the length of the run. The NEC also says that two pedestals with the same feeder can be de-rated to 90%.

One other thing... The NEC considers a power pedestal to be a "feeder", not a branch circuit. Therefore, although the circuit 'may' technically be allowed to not carry a neutral (white) conductor, I would highly recommend that you insist on a 4-wire feeder: That is two blacks, one white, and one ground (two ungrounded conductors, one grounded conductor, and one grounding conductor). If something were to happen to go bad with the grounding rod connection your entire trailer would go 220 volts and bad things could happen...

The grounding (ground) wire is allowed to be smaller than the rating of the ungrounded conductors (black wires) according to a table in the NEC.

[SolarPoweredRV]

I am a licensed electrician and I can unequivocally say that 4/0 Aluminum is what I use for 200 amp service/entrance wiring to a home. According to National Electrical Code (NEC), 4/0, 4/0, 4/0, 2/0 copper cable is good for 260 Amps per phase!

There are new rules for installing power pedestals for RV's, including the requirement for a 30 Amp-220 volt receptacle and a GFI-protected 20 amp-120 volt outlet.

Your electrician 'may' have included a deration factor for the length of the run. The NEC also says that two pedestals with the same feeder can be de-rated to 90%.

One other thing... The NEC considers a power pedestal to be a "feeder", not a branch circuit. Therefore, although the circuit 'may' technically be allowed to not carry a neutral (white) conductor, I would highly recommend that you insist on a 4-wire feeder: That is two blacks, one white, and one ground (two ungrounded conductors, one grounded conductor, and one grounding conductor). If something were to happen to go bad with the grounding rod connection your entire trailer would go 220 volts and bad things could happen...

The grounding (ground) wire is allowed to be smaller than the rating of the ungrounded conductors (black wires) according to a table in the NEC.

Why would the NEC require a 220v 30 amp outlet? The TT-30 connector is a 120 volt 30 amp outlet for the camper, any 220 volt 30 amp connector would just confuse the users.

In one of my earlier posts I warned the OP about Electricians wanting to wire the 30 amp outlet as 220 volt and not understanding that the 30 amp outlet is only 120 volts.

[nbking]

50 amp requires 4 wires, 2 hot 1 neutral 1 ground. 6awg wire will work on a short runs, but since it's so far 4awg wire will lessen the voltage drop. Both hot legs for the 50amp, he'll steal one hot leg for the 30amp, and the other for the 20amp. By code the ground rod should be at your main panel. You don't need a separate ground at your trailer, as it will get ground through your cord.

[Jerryr]

50 amp requires 4 wires, 2 hot 1 neutral 1 ground. 6awg wire will work on a short runs, but since it's so far 4awg wire will lessen the voltage drop. Both hot legs for the 50amp, he'll steal one hot leg for the 30amp, and the other for the 20amp. By code the ground rod should be at your main panel. You don't need a separate ground at your trailer, as it will get ground through your cord.

It’s not just a 50 amp 14-50R NEMA receptacle requiring 6 AWG wire. He’s talking of installing 2 each 50/30/20 RV 100 amp pedestals. They are all ready wired internally and have 3 circuit breakers in each box. It’s hard for an electrician to misswire the pre wired the individual receptacles in the RV box.

It will be a nice setup.

This is a picture of one like it.

[PappaJohn]

OK. I forgot that you are providing power to two pedestals.

I would suggest that you bring the ground wire from your electrical panel which will be directly connected to the neutral wire at the service entrance. People often think ground is ground is ground meaning that the ground is at the same potential all over. This is pretty much true under normal circumstances.

The most dramatic case where the ground voltage is not constant is if there is a lightning strike close to your house. I have seen cases where the voltage can vary thousands of volts over the distance you are talking about. The issue becomes that the 120/240 is referenced to one ground and your trailer is referenced to another ground that instantaneously is thousands of volts different. I have seem this do many thousands of dollars of damage at industrial sites.

John

[DougW9876]

I would go with the 4 wire and I would go ahead and put in a ground rod at the pedestal. It is not necessary but in the overall pricing of this project the cost of a ground rod will be negligible and it will give you an added margin of safety.

I am not sure about putting GFCI at the pedestal, I have seen lots of posts on forums about problems with the GFCI outlets in the RV’s tripping because having a GFCI in the trailer protected by a GFCI in the pedestal sometimes makes them trip for no good reason.

[rogercwhite]

I am not sure about putting GFCI at the pedestal, I have seen lots of posts on forums about problems with the GFCI outlets in the RV’s tripping because having a GFCI in the trailer protected by a GFCI in the pedestal sometimes makes them trip for no good reason.

The GFCI is only for the 110V 20A circuit. That will be used to run external electrical devices like a compressor or electric pressure washer so I don't risk running through my trailer.