30 amp RV outlet box

[Sweetfarm]

Hi there, I am trying to run an outlet for my 30 amp RV from my house. I am having a trench dug and I’m going to use 10 gauge direct bury wire. Wondering if it’s possible to use this outlet box?

https://www.homedepot.com/p/Midwest-Electric-Products-70-Amp-Power-Outlet-Box-U041CP/202307106

 

[pc1966]

No idea about the USA regulations! But here in the UK for a caravan outlet you would need a RCD (residual current device = GFCI) on the supply. Have you got that on the main board you plan to feed this from?

If not you should get a version with the GFCI built in, but really the best protection is putting the GFCI at your board as will detect faults on feed cable to the outlet as well.

Also in the UK you would need to check the voltage drop of the cable, so a very long run might need heavier gauge for that reason. Again, might not be a factor over the pond.

 

[Sweetfarm]

No idea about the USA regulations! But here in the UK for a caravan outlet you would need a RCD (residual current device = GFCI) on the supply. Have you got that on the main board you plan to feed this from?

If not you should get a version with the GFCI built in, but really the best protection is putting the GFCI at your board as will detect faults on feed cable to the outlet as well.

Also in the UK you would need to check the voltage drop of the cable, so a very long run might need heavier gauge for that reason. Again, might not be a factor over the pond.

Thank you! That’s a very good point and I will get a GFCI circuit breaker.

 

[pc1966]

As I said, the UK and USA electrical practices are very different but there are common requirements. I don't really know the type of wire you mean to use, is it this:

https://www.homedepot.com/p/Cerrowire-50-ft-10-3-UF-B-Wire-138-1803BR/306300239

It looks similar to our "twin and earth" but here T&E is not suitable for outdoor use. We would typically use SWA (steel wire armour) cable, and usually the outer armour is used as the earth (ground) so here 3 core + armour for your 3-pole socket outlet, though we would check if the armour is enough as sometimes you would need 4 core since steel is around 8 times poorer as a conductor compared to copper and that is not always made up for by the extra amount used in the armour.

We also use the NYY-J type of cable outdoors, it looks initially like round flex but is stiff and quite tough outer, and the HO7RN-F tough rubber flex. But neither are as tough / rodent-resistant as SWA! They are easier to terminate though, you don't need the special glands for SWA types, more or less any gland of the right diameters is sufficient when you don't have the armour.

If you have any doubts about physical protection you can always put in some duct so long as it has gentle bends to pull the cable though easily. Again, no idea about USA practice but here for burying a low voltage cable under a footpath it would usually be 45cm (around 18 inches) or 60cm under a roadway. In case you wonder, to power engineers anything below 1000V AC is "low voltage" and below 50V AC is extra low voltage!

In the UK that gauge of cable is close to our 6mm cross-sectional area wire and on a 30A outlet would be acceptable to around 45m (148 feet) on voltage drop, but again that might not apply to you.

Again, we would put something like this on its own dedicated breaker at the board, and ideally a GFCI type there. Some prefer the GFCI at the outlet so it is easier to reset, and for SWA cable that is safe (as if by some amazing attempt at damage it is penetrated then it shorts out and trips any breaker). If it is your home, and not a rental place, it hardly matters for access and having the protection at your main board for the feed cable as well is always good!
[automerge]1588872352[/automerge]
Just to add - in the UK adding a new circuit (e.g. new breaker to the main board) is a job for a competent person, usually taken as a professional electrician.

You should check the situation in your state, and if there are any clauses in your insurance on that as well. Getting professional help is always a good idea, but with some discussion they may be happy for you to do a portion of the work and then finish/test/sign-off.

 

[Megawatt]

As I said, the UK and USA electrical practices are very different but there are common requirements. I don't really know the type of wire you mean to use, is it this:

https://www.homedepot.com/p/Cerrowire-50-ft-10-3-UF-B-Wire-138-1803BR/306300239

It looks similar to our "twin and earth" but here T&E is not suitable for outdoor use. We would typically use SWA (steel wire armour) cable, and usually the outer armour is used as the earth (ground) so here 3 core + armour for your 3-pole socket outlet, though we would check if the armour is enough as sometimes you would need 4 core since steel is around 8 times poorer as a conductor compared to copper and that is not always made up for by the extra amount used in the armour.

We also use the NYY-J type of cable outdoors, it looks initially like round flex but is stiff and quite tough outer, and the HO7RN-F tough rubber flex. But neither are as tough / rodent-resistant as SWA! They are easier to terminate though, you don't need the special glands for SWA types, more or less any gland of the right diameters is sufficient when you don't have the armour.

If you have any doubts about physical protection you can always put in some duct so long as it has gentle bends to pull the cable though easily. Again, no idea about USA practice but here for burying a low voltage cable under a footpath it would usually be 45cm (around 18 inches) or 60cm under a roadway. In case you wonder, to power engineers anything below 1000V AC is "low voltage" and below 50V AC is extra low voltage!

In the UK that gauge of cable is close to our 6mm cross-sectional area wire and on a 30A outlet would be acceptable to around 45m (148 feet) on voltage drop, but again that might not apply to you.

Again, we would put something like this on its own dedicated breaker at the board, and ideally a GFCI type there. Some prefer the GFCI at the outlet so it is easier to reset, and for SWA cable that is safe (as if by some amazing attempt at damage it is penetrated then it shorts out and trips any breaker). If it is your home, and not a rental place, it hardly matters for access and having the protection at your main board for the feed cable as well is always good!
[automerge]1588872352[/automerge]
Just to add - in the UK adding a new circuit (e.g. new breaker to the main board) is a job for a competent person, usually taken as a professional electrician.

You should check the situation in your state, and if there are any clauses in your insurance on that as well. Getting professional help is always a good idea, but with some discussion they may be happy for you to do a portion of the work and then finish/test/sign-off.

Hi there, I am trying to run an outlet for my 30 amp RV from my house. I am having a trench dug and I’m going to use 10 gauge direct bury wire. Wondering if it’s possible to use this outlet box?

https://www.homedepot.com/p/Midwest-Electric-Products-70-Amp-Power-Outlet-Box-U041CP/202307106

Sweet
Sweetfarm yes you can use that receptacle and it’s a NEMA 3 box or rain proof. That would work perfect