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The 200a main disconnect is mounted under the meter on the power pole. It has spaces for 8 breakers and a neutral bus bar. The only ground I see is from a rod at the base of the pole to the meter. I've run 50' of #8 2wireuf from the 30a rv pedestal to the main in PVC conduit. The neutral and ground are separated at the pedestal. I intend to put the neural and ground on the single bus bar. The question is do I run #4 bare from the existing rod to the neutral bus bar in the main and put in 2 at the pedestal.

  • @jphi1618 That is a 50 amp question 240v. A 30amp RV service is 120v. – Ed Beal Jan 29 at 19:46
  • What size PVC conduit did you run? – ThreePhaseEel Jan 30 at 2:28
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    Used 1" sucked a mouse through with shop vac to get the rope through and a little wire pulling lube worked slick as a whistle. – Philip Navin Jan 31 at 7:25
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As this is at the main it would be fine to have both your neutral and ground on the same buss. an RV “park” doesn’t require an additional grounding electrode NEC 551.75.b
However 1 out of 3 of the counties I work in requires a supplemental ground at the pedestal as this a residential hookup not a park.

Make sure to have your box 2 feet off the ground or more but not over 6’6”.

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  • Thanks, when we get the cabin built and move the rv we'll treat it as a sub. So I do need to put a ground on the main for bonding? – Philip Navin Jan 29 at 20:26
  • I am not sure I follow , if you are connected at the main the ground and neutral can be on the same buss in the main, they can not be combined at the pedestal. The only place that the neutral can be connected to the ground is the main panel. – Ed Beal Jan 29 at 20:37
  • As a he only ground I see at the pole goes into the meter box which is connected to the main by a metal nipple can I assume it is grounded? – Philip Navin Jan 29 at 20:43
  • Yes the metal (boxes) are required to be bonded the nipple is the method that connects the 2 boxes. – Ed Beal Jan 29 at 20:48
  • Your insight is greatly appreciated. – Philip Navin Jan 29 at 20:50
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You can't run neutral and ground on the same wire!

I've run 50' of #8 2wireuf from the 30a rv pedestal to the main in PVC conduit. The neutral and ground are separated at the pedestal.

At the meter, you are allowed to combine your neutral and ground bars into one bar. It's not ideal but it's legal. At the RV pedestal, neutral and ground must already be separated: you absolutely must run separate ground and neutral wires from the service panel to the RV pedestal. Sorry if I'm misunderstanding, but I'm unclear what you're saying.

As such, the only thing your 8/2 cable can support is a "TT30", a 120V/30A connector used by small pop-up campers. If you are installing a TT30, you're all set, and you can skip to the next part.

However, if you are trying to support a 240V/30A NEMA 14-30 for a midsize RV, then I'm sorry you wasted $60 on that cable, but it can't be used here. Pull it out and find someone who is installing an electric range. You can't use cable here.

(well, there's one option to use it: connect ground to ground, neutral to neutral, and hot to both hots. However 240V loads won't work and your 120V loads will be limited.)

In conduit, use individual wires, not cable

With flat cables, you must use a much larger conduit than you think -- 8/2 UF requires a 1" conduit (assuming there is only the one cable in the conduit, and then it's at absolute conduit fill limits). Since it twists, it's treated as a round wire of the large dimension. If your conduit is not 1", the 8/2 UF must be removed, period.

The right thing to use is THWN-2 type individual wires. The bare minimum allowed is #10 copper wires. You can also run #8 copper or #6 aluminum, both of which will allow you to upgrade to a 50A receptacle in the future. Three #6 THHN wires + one #10 bare ground wire will fit inside either a 3/4 or 1" conduit. They will also be much, much, much easier to pull than that UF cable.

For a single circuit/receptacle, no ground rod needed and a #10 ground wire needed. If you ever put a subpanel there, then yes. Keep in mind that a ground rod will not replace a missing ground wire. Dirt does not conduct electricity very well.

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    It's a NEMA TT30R. The main has only one bus bar where the ground and neutral are attached. In the TT30 the hot and neutral are attached to their respective spots on the socket. The green wire on the socket is connected to a bus with the ground coming from the main. The wire is run through 1" PVC. – Philip Navin Jan 31 at 6:52
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You may or may not need a second rod at the power pole

In a meter-pole service configuration, the number and type of ground rods used at the pole is a function of the serving utility's requirements. This is because the NEC does not require grounding electrodes for a meter-pole or pedestal, only at buildings or structures, as per 250.50:

250.50 Grounding Electrode System. All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system. Where none of these grounding electrodes exist, one or more of the grounding electrodes specified in 250.52(A)(4) through (A)(8) shall be installed and used.

...but you certainly don't need one at the RV pedestal

However, RV pedestals/outlets do not need a ground rod at all, as NEC 551.75(B) expressly permits RV pedestal installations to omit a grounding electrode:

(B) Grounding Electrode. Power outlets or recreational vehicle site supply equipment, other than those used as service equipment, shall not be required to have a grounding electrode. An auxiliary grounding electrode(s) in accordance with 250.54 shall be permitted to be installed.

As to the cable in the conduit...

Your 8/2 W/G UF-B cable is equivalent to a .620" round cable for conduit fill purposes, and thus takes up 195mm2 of fill area. Given that a single wire in a 1" Schedule 80 PVC conduit is allowed to take up 236mm2 of area, your UF cram job thankfully fits in the conduit by Code, but certainly wasn't an easy pull!

While you don't need to rip it out, let your struggle with the pull be a lesson to you: cables don't belong in conduits. Instead, you should use individual THHN-insulated wires; they are much slicker than the outer jacket of most cables, making pulling much easier, and are also available in stranded constructions even in small sizes like 14AWG and 12AWG, thus making pulling and handling yet easier as well. Keep this in mind if you ever wish to upgrade this RV setup to 50A.

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  • It pulled easy as pie. A little pulling lube works wonders. I'll keep that in mind in the future. – Philip Navin Feb 1 at 6:10

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