30 Amp RV electric wire size question

[Rusty Heap]

In college as a EE engineering student we got a behind the scenes tour of a hydroelectric dam on the Columbia River. The "wire" coming right out of the Turbine Pit and generator was ultra pure copper, 1" thick x 6" wide plate.

[rfuerst911sc]

OK so sub panel it is . Yes I will want one or two 110 outlets and some lights in addition to the RV outlet . And consensus says use THNN in conduit . If I have this right feed the sub panel via a 50 amp double pole breaker . Use # 6 THNN wire qty 4 . That would be two hot , one neutral and one ground .

In the sub panel install a 30 amp single pole breaker to feed RV outlet . Install 15 and 20 amp single breakers to feed 110 lights and outlets . Grounding rod needed for sub panel . Does that sum it up ?

Where I want to install the sub panel is aprox 8 ' in from an open end of the carport . I don't think wind driven rain would get that far but I can always enclose the sub panel with a wood box . This discussion has been helpful . Thank you

[javadog]

Put the RV breaker on one leg and the other recepts on the other leg. The more you balance the loads on the two hots, the less current you'll have on the neutral. I think you need two ground rods, x feet apart, to meet code.

[jyl]

Question - why would a ground wire be pulled through the 75' conduit from main to subpanel? Subpanel needs its own local ground rods. I am not sure what a pulled ground wire would be used for?

Edit: I vaguely recall I pulled ground wire from the main panel to my subpanel. It was inspected and all that, so was probably "correct". But thinking about it, I don't genuinely "understand" why I did that; maybe I did at the time but if so have forgotten. Not an electrician, obviously.

Also question - can you actually place an electrical panel inside a cabinet or other enclosure? There is some code language about the entire vertical space occupied by the panel, from floor to ceiling, has to be clear of anything not part of the electrical system.

[dad911]

You don't normally need an 'earth' ground for a sub panel. As I recall, 'Earth' ground for a sub panel is for remote detached structures (workshop etc) and pool equipment sub panel. Sub (in the same structure) gets ground from main panel. Although in the main panel grounds and neutrals are attached to the same bus bar, in a sub panel there is a separate bus bar for neutrals and grounds, 2 busbars total. The ground bar is attached to the panel with a bonding screw while the neutral bar does not. Yes to 4 wires, 2 hots typically black & red, a white neutral, and a green ground (bare in romex) insulated if pulling through conduit.



Pics here:

https://ep2000.com/understanding-neutral-ground-grounding-bonding/?v=e75edac1b83f

[A930Rocket]

Originally Posted by javadog

I think you need two ground rods, x feet apart, to meet code.

6’ apart, minimum.

[A930Rocket]

Originally Posted by jyl

Also question - can you actually place an electrical panel inside a cabinet or other enclosure? There is some code language about the entire vertical space occupied by the panel, from floor to ceiling, has to be clear of anything not part of the electrical system.

I don’t think you have to build a cabinet but a panel to protect it, that would cover the breaker box cover. You could swing the panels/door open to fully access the breaker box and cover.

As long as you have the panel anywhere within 3 feet horizontally* and 3 feet Working room in front of it, you are good to go.

* Code doesn’t require the breaker box to be centered on 3 feet. Knowing that, has helped us a couple times.

[jyl]

Originally Posted by A930Rocket

I don’t think you have to build a cabinet but a panel to protect it, that would cover the breaker box cover. You could swing the panels/door open to fully access the breaker box and cover.

As long as you have the panel anywhere within 3 feet horizontally* and 3 feet Working room in front of it, you are good to go.

* Code doesn’t require the breaker box to be centered on 3 feet. Knowing that, has helped us a couple times.

I read in some electrical forum that the panel "cabinet" can must have sides 3' apart and no top or bottom to meet code. So, wouldn't actually weatherprood the panel.

I guess depends on how picky the inspector is. I had my main panel replaced, the guy said my freezer was 0.5" too close to the panel front and wouldn't sign off, when he came back to re-inspect the freezer was sitting three feet away on an extension cord and obviously would be going right back to its original illegal location, but he signed off without a word. But my city is notoriously a PITA on permits. I do everything possible without permits.