50 amp 3 pole 4 wire service?

[Tony Stanek]

Needing to wire service for an RV. Uses a "50 amp 120/240-volt 3pole 4 wire grounding service" hook up. Wiring to a 70 amp breaker box directly below a meter base on a temp pole set up. Will be running wire about 40 ft. underground to four pole plug in a metal box, which is where cord for trailer will plug into. Breaker box has a common ground/neutral buss bar, not seperate ones. My question is, Seeing as the ground and neutral are common in the breaker box, could I run just an encased 4/3 cable to the plug box and then jumper the ground and neutral wires at the plug intead of getting another wire to run along side the encased wires? They will be coming off the same buss in the breaker box anyway, why get the extra wire? Or do I need to get another breaker box, with a seperate ground and neutral buss ( which will more than likely be bonded in the breaker box )?

[Jim Luttrall]

No offense Tony but if you have to ask those questions, you really should hire an electrician. RV service looks simple but can be deadly.
But no, you cannot omit the 4th wire. There is a separate ground / neutral for a reason.

[Tony Stanek]

So Jim, I need to get another breaker/service panel with a seperate grounding bus????

[Rick Cantrell]

So Jim, I need to get another breaker/service panel with a seperate grounding bus????
Tony
Jim said what you need to do.

No...you.. should hire an electrician.
RV service...can be deadly.

[Steven Turetsky]

Maybe I'm not understanding your description, but I question your whole installation. For 120 you need a neutral, and for 240 you need 2 hots; is the 3rd wire your neutral? So where is your ground? And an additional isolated ground (or grounding rod)is most likely required.

Even if you supply the labor to dig the trench, it sure makes sense to have a real electrician oversee the install and make the connections.

[Brad Richter]

A branch circuit does not require a ground rod or grounding electrode system.

[Aaron Miller]

As long as you have a grounding conductor present and properly connected in the cable going to the RV no ground rod is required. If a generator is included in the mix it may be required. See: http://www.osha.gov/OshDoc/data_Hurricane_Facts/grounding_port_generator.pdf

[Steven Turetsky]

A branch circuit does not require a ground rod or grounding electrode system.

Does the 70 Amp breaker being fed on the pole need a grounding electrode? As far as the metal box housing the 4 prong outlet being fed from 40' away underground, I always thought when running a feeder underground to a remote location, like a garage or satellite dish, Etc. you need a grounding system.

Does he not need the 4th conductor? He is talking about using a neutral as a ground to eliminate a 4th conductor.

[Al Neuman]

You can't use a 70 Amp breaker with a 50 Amp receptacle in the first place......

Like the others, I recommend you hire a competent electrician.

[Speedy Petey]

So where is your ground? And an additional isolated ground (or grounding rod)is most likely required.You need to read up on the purpose and function of grounding electrodes and equipment grounds.

A grounding electrode (ground rod) can NEVER take the place of an equipment ground. The earth is NEVER to be used as a path for fault current. EVER.

[Speedy Petey]

Needing to wire service for an RV. Uses a "50 amp 120/240-volt 3pole 4 wire grounding service" hook up. Wiring to a 70 amp breaker box directly below a meter base on a temp pole set up. Will be running wire about 40 ft. underground to four pole plug in a metal box, which is where cord for trailer will plug into. Breaker box has a common ground/neutral buss bar, not seperate ones. My question is, Seeing as the ground and neutral are common in the breaker box, could I run just an encased 4/3 cable to the plug box and then jumper the ground and neutral wires at the plug intead of getting another wire to run along side the encased wires? They will be coming off the same buss in the breaker box anyway, why get the extra wire? Or do I need to get another breaker box, with a seperate ground and neutral buss ( which will more than likely be bonded in the breaker box )?
Sorry Tony, there is SO much wrong here, in practice and in theory, that I agree with the others. PLEASE hire an electrician to do this job correctly.
Just knowing how to connect wires does not mean one is capable of doing a job like this safely. v

[Steven Turetsky]

You need to read up on the purpose and function of grounding electrodes and equipment grounds.

A grounding electrode (ground rod) can NEVER take the place of an equipment ground. The earth is NEVER to be used as a path for fault current. EVER.

I never said that an equipment ground takes the place of a grounding electrode. I mentioned a few things that may be necessary, and also stated that His description wasn't too clear (to me).

[Speedy Petey]

I never said that an equipment ground takes the place of a grounding electrode. I mentioned a few things that may be necessary, and also stated that His description wasn't too clear (to me).
Sorry, that's the way it read in the line I quoted above.