Rv temporary 30 amp 120v outlet ground question

[roadrunner255]

I will be installing a rv outlet for our new motorhome, total run is about 70', (46' inside in emt, 24' outside buried pvc).
According to the 3% voltage drop calc I would need to use 8g (58' max) conductors, could I use 12 or 10g for ground and would the ground need to come from the panel or could I tap into a ground at the nearest metal box?

Cheers!

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[nadogail]

IMHO, Take the ground back to where you get your feed from.

 

[wyliesdiesels]

I will be installing a rv outlet for our new motorhome, total run is about 70', (46' inside in emt, 24' outside buried pvc).
According to the 3% voltage drop calc I would need to use 8g (58' max) conductors, could I use 12 or 10g for ground and would the ground need to come from the panel or could I tap into a ground at the nearest metal box?

Cheers!

Sent from my SM-N950U using Tapatalk

which voltage drop calc did you use?

did you do it manually?

I posted the equation on the FAQ thread

As far as the ground wire goes, 30a requires #10 and the EGC size required is also #10. When you upsize the ungrounded conductors for voltage drop or other reasons, the EGC needs to be upsized as well, proportionately as the same amount as the ungrounded conductors. Since the required EGC (before upsizing) is #10, this would mean the EGC would be the same size as the ungrounded conductors.

As to connecting to a nearby ground wire, I wouldnt bother. Run all 3 wires together. You will need a white wire and a green wire since <#4 cannot be phase taped.

 

[roadrunner255]

Thanks, used southwires calc.

Using your calculator 1.26 R @70' for 120v equal a 4.4% v drop using 10g.

Appreciate the feed back!

Any gfci required?

Rv uses a surge protector.

 

[wyliesdiesels]

Southwires calc notoriously oversizes the wire (hmmm i wonder why). Doesnt sound like they did in this case...

Will you be running the RV full tilt- A/C, cooking, heating water etc. or just charging/storing?

I doubt youll run the full 30a so you may be able to get by on #10 but depends on usage.

 

[sberry]

The ground must be ran with the ungrounded conductors. Use 10. 70 ft is not super close but it's not all that far either.

 

[AntonLargiader]

How temporary? And what will you do while it's plugged in? I run ours on a 20 all the time.

 

[theoldwizard1]

Install a MicroAir EasyStart and I will bet you can use a 20A breaker and accordingly sized wire. Your generator will be happy also !

 

[roadrunner255]

Would just be used for charging and heat should temps get below freezing which doesnt happen much here in central texas.

20amp is perfect, I already have exterior mounted receptacle gfci outlets that I can run conduit to the rv about 30'.

Thanks again all!

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[Showkey]

How temporary? And what will you do while it's plugged in? I run ours on a 20 all the time.

This^^^^^^^^^^^^^^^^^This

Install a MicroAir EasyStart and I will bet you can use a 20A breaker and accordingly sized wire. Your generator will be happy also !

20 amp circuit starts and runs mine with no problem without easy start.
Just can’t run the 1000w microwave or electric water heater at the same time.


20-30% of the camp grounds only have 20 amp as the choice on the post.

 

[AntonLargiader]

The RV I mention is a Winny/VW Rialta and I have no problem running AC on 20A. For occasional use I'd just run the RV cord to that recep with a 30->20 or 30->15 adapter or use a nice extension cord.

 

[ezzzzzzz]

Run the #8 in 3's back to the panel. Use a 30amp standard breaker and a RV 30amp box on a post. The cost difference is negligible and ensures you'll have want you need.