?s About Installing Shore Power

**RickO** · 07-15-2011, 03:30 PM

Last year I began a thread asking for advice about installing shore power at my FILs old farm house in Minnesota. I got great responses including many valuable links to "how to" information. At the time the plan was to install a pedestal at the end of a 100' buried cable run with either 30 or 50 amp service. For reasons I won't go into, work on this hasn't yet begun and we're stuck with only 20 amp service again.

We're currently nearing the end of our month long stay but I'm wanting to nail down plans to ensure we'll have better power when we return.

Since my research last year I have modified my objectives to save money and hassle. We can move the coach to be set up much closer to the house to take the cable run from 100' to 50' from the main service panel to the sub panel. I can use the coach's 50 amp service cable (6/3) along with a 25' (6/3) extension cable to connect to the new sub panel which I want to locate just inside the basement door.

Some background: 1) This is a 100 year old farm house. 2) the service panel appears to be modern but is only 100 amp. Some but not all house wiring appears to have been updated. 3) This is in a very rural area and the electrician my FIL has used claims to have a license but strikes me as a shade tree electrician. 4) It is unclear just how many more visits we'll be making to this location so I'm trying to be frugal and simple while remaining safe. 5) The house itself doesn't have many hi-amp modern appliances. Electric dryer and microwave is about it.

Proposal: I would like to run 8/3 grounded cable from a double 30 amp breaker in the main service drop to a sub panel just inside the cellar door. Cable from the coach can be run under the door to the sub panel. The sub panel would be wired just like a typical 50 amp RV service except be protected at both ends by 30amp rather than 50 amp breakers. This should provide me with 60 amps of service which should be fine and since I'm going directly to the main service panel I won't rely on any aging wiring in the house.

My Questions Are:

1) I've read that ALL RV sub panels require a dedicated ground rod but this installation is inside a concrete basement so will reliance on the main ground wire to the service panel be sufficient?

2) From my reading of wire sizing charts, 8/3 cable for a 50' 30 amp run is sufficient but from there I'll be attaching my coach service cable and 25' extension cord (6/3) so should the house wire also be 6/3 because of the longer run?

3) Given the objectives of getting more power to the coach while not over taxing the house 100 amp panel, keeping cost down, simplifying installation, and remaining safe... does this approach make sense?

Thanks much in advance for any insights.

Rick

**Route 66** · 07-15-2011, 03:38 PM

Your questions are?

I have drawn about 35 amps on a leg in the past. I think I had the Air Conditioner, dryer and all the normal stuff on.

**RickO** · 07-15-2011, 03:50 PM

Quote:

Originally Posted by Route 66

Your questions are?

I have drawn about 35 amps on a leg in the past. I think I had the Air Conditioner, dryer and all the normal stuff on.

Sorry Dirk, I fat fingered it and posted before I was finished and had to add them on edit.

My Questions Are:

1) I've read that ALL RV sub panels require a dedicated ground rod but this installation is inside a concrete basement so will reliance on the main ground wire to the service panel be sufficient?

2) From my reading of wire sizing charts, 8/3 cable for a 50' 30 amp run is sufficient but from there I'll be attaching my coach service cable and 25' extension cord (6/3) so should the house wire also be 6/3 because of the longer run?

3) Given the objectives of getting more power to the coach while not over taxing the house 100 amp panel, keeping cost down, simplifying installation, and remaining safe... does this approach make sense?

Rick

Bill Adams · 07-15-2011, 03:57 PM

Since 50 amp service allows that RV to use as much as 100 amps (50 amps on each leg) are you sure 50 amp service is what you want to run from a 100 amp box? I may have misunderstood and you are just going to run a 30 amp run and keep the RV power usage limited.

Tha_Rooster · 07-15-2011, 04:05 PM

I would think for safety reasons it would be a good idea. I will be running power to my unit where it is stored about 75 feet from panel and I will install a rod at pedestal.A friend who is an electrician told me I should who has no financial gain.

**RickO** · 07-15-2011, 04:06 PM

Quote:

Originally Posted by Bill Adams

Since 50 amp service allows that RV to use as much as 100 amps (50 amps on each leg) are you sure 50 amp service is what you want to run from a 100 amp box? I may have misunderstood and you are just going to run a 30 amp run and keep the RV power usage limited.

Thanks Bill. I got the idea from a earlier suggestion on the subject. The idea is to limit each leg of the "50 amp connection" to 30 amps to avoid overloading the main 100 amp panel. Everything gets wired just as a typical 50 amp set up except it is actually limited to 30 amps per leg by the 30 amp breakers.

I am a bit concerned about running a 50 amp (x2) connection from the 100 amp panel and this suggestion seemed to give me a way to get between the typical 30 amp connection and the potential 100 amp connection provided by a standard 50 amp RV connection.

30 amp isn't quite enough to make the coach happy and 100 amp is too much for the house to be happy.

Rick

Don/Lou · 07-15-2011, 04:13 PM

"Everything gets wired just as a typical 50 amp set up except it is actually limited to 30 amps per leg by the 30 amp breakers."

This is how i did it about 5 years ago
No problems !
Don