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Topic: 50 amp Wiring - Getting it right the first time. (Read 1095 times) previous topic - next topic

50 amp Wiring - Getting it right the first time.

At the residence where I rent the space to keep my Coach during its restoration, the homeowner is now going to supply me with a 50 amp 120V hook-up. His plan was to tap off where his main A/C unit sits on a pad next to the house, as he tells me this is a 220V 50 amp location.

My plan is to have a friend who is a licensed Electrician come over and do the job.

My question is:

Is there any special needs as far as the identification of the terminals on the Coach where my 50 amp shore power cord hooks up that I need to know about or pass on?

I seem to remember reading somewhere that when pulling power from home wiring into a RV -- certain precautions have to be taken. My Electrician buddy has done boats at Marina's, and also says he had experience in years past correcting problems at RV parks, but this is just information I'd like to have for myself.

A picture of the socket on the Coach, with an identifying of each terminals assignment, and one for the shore power cord connectors -- would be excellent.

By the way, he said one of the biggest problems at older RV parks is that they used cheaper aluminum wire that tends to expand and shrink with load, and over time ultimately creates bad/loose connections from oxidizing that cause current flow choke points and voltage swings.

Anyway -- any comments appreciated.

Be safe out there,

Michael
Michael
1995 U300SE CAT 3176B Build # 4612 ("Marvin")

Re: 50 amp Wiring - Getting it right the first time.

Reply #1 –
Quote from: geomm –
At the residence where I rent the space to keep my Coach during its restoration, the homeowner is now going to supply me with a 50 amp 120V hook-up. His plan was to tap off where his main A/C unit sits on a pad next to the house, as he tells me this is a 220V 50 amp location.

Anyway -- any comments appreciated.

Here's a great place to start

RV Electric

As you'll read, you either want a 120V 30 amp (single phase) RV connection - which is NOT a 30 amp 240V household appliance connection - that would damage your coach - OR you want a 50 amp, 240V two-phase connection (which is a total of 100 amps, 50 on each 120V phase).

Oh, and not knowing the current draw of his A/C unit, I would be very extremely leery of using the same circuit for his A/C as your coach.  If both his A/C started up AND your coach pulled significant current, you risk the circuit not being adequate, voltage drop, etc.  RV connection should be on its own circuit/breaker.

Quote from: geomm –

By the way, he said one of the biggest problems at older RV parks is that they used cheaper aluminum wire

Aluminum wiring can be a problem.  Also, possibly more often because the parks originally wired with 20 Amp or 30 Amp service with no upgrades to the infrastructure when they "upgraded" the sites to 50 amp receptacles (without proper gauge wiring or truly separate-phase hots or adequately-sized neutral).
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: 50 amp Wiring - Getting it right the first time.

Reply #2 –
In addition to Michelle's excellent comments I have a few.

The use of the A/C drop could work, but (and your electrician friend should know this), for a 50 amp 240 volt RV connection you need a dedicated neutral wire, which would be a 4-wire cable (with 2 hot wires, neutral and ground) to the junction box.

A lot of A/C junction boxes (including mine here at my house that was built just 8 years ago) are wired without a dedicated neutral (with 2 hot wires and a ground), because code allows this for A/C units, and because the wire is cheaper without the 4th wire.

Also, your friend should know that you cannot just use the ground wire as the neutral wire, a shortcut that many think is ok.

Good luck...
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B

Re: 50 amp Wiring - Getting it right the first time.

Reply #3 –
Yup, 4 wires.

Outer straights are the HOTS (240 VAC as measured between them).

Center straight is NEUTRAL.

Center round is GROUND.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: 50 amp Wiring - Getting it right the first time.

Reply #4 –
Should add for 50 amp service you need 6 ga wire or larger, not smaller.

Re: 50 amp Wiring - Getting it right the first time.

Reply #5 –
So having looked at the situation with the existing 220/50 amp junction box for the home A/C unit, it has been decided to not tap off of that because it is a 3-wire installation. And -- because of the points brought up by a few of you, that it might overload and trip the breaker under certain conditions)

Instead, we are running a 80-foot dedicated line of 6-3 Romex (which has 3 wires and the ground wire) to the main 200 amp service panel with two 50 amp breakers.

If I understand it correctly, the line will carry 240 volts, but when connected to the Coach, the ATS handles that and provides the 120 volts the Coach requires.

I have a Magnetek ATS 100 Type 1 -- rated at 240 VAC with a tungsten 50 Amp ballast.

Is this correct?
Michael
1995 U300SE CAT 3176B Build # 4612 ("Marvin")

Re: 50 amp Wiring - Getting it right the first time.

Reply #6 –
Yes, similar to a stick house, the two hots (240 measured between them) go to the motorhome, but all your appliances work off just ONE hot, the neutral and ground.

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: 50 amp Wiring - Getting it right the first time.

Reply #7 –
Thanks for the confirmation, Brett.
 
This Saturday -- is the plan. I'm just running off the inverter/batteries until then. There still is the issue of the "Gen-set wandering output" , a modulating in sound, and the Powerwatch meter above the entry door ,needle, moving between 110 and 120 volts. I changed the fuel filter and it went away for about 5 minutes, but started hunting again.

This only happens when under load with a A/C unit going, and it gets worse with both units running. I suppose it is time to change-out the fuel feed hose.

I officially moved into it full-time on July 1st, so now I hope to be able to finish my list of projects a lot sooner that when I was only here on weekends. That is, every weekend since last October.

Be safe out there, everyone!

 
Michael
1995 U300SE CAT 3176B Build # 4612 ("Marvin")

Re: 50 amp Wiring - Getting it right the first time.

Reply #8 –
Michael,
I just ran an outlet last fall for my FT.  If you would like a pic inside my panel I will send you one.  I would need your email.  I dont know how to post a pic on the forum.
There is nothing special about it.  Just 2 hot legs a neutral and a ground.
Dont know what you have in mind to mount your box but I found a simple solution.  I bought a mailbox mount that drives in the ground (approx. 1400) from Home depot and mounted a 12in pc. of treated 4X4 to mount the box on.  Looks nice and an easy install. 
Jerry
Jerry & Nanci
1999 U270 34'WTFI
2011 Malibu
A smart man knows what to say, a wise man knows when to say it.

Re: 50 amp Wiring - Getting it right the first time.

Reply #9 –
Jerry,

Thanks for the offer. We completed the running of a 80' 6-3 romex dedicated line off of the 200 amp main panel on the house -- on Sunday. So, I have a 50 amp, 240 Volt box now that I plug my shore power cord into.

It's been great ! I was finally able to confirm operation of some appliances that only run on shore power. Everything's operating well.
Michael
1995 U300SE CAT 3176B Build # 4612 ("Marvin")

Re: 50 amp Wiring - Getting it right the first time.

Reply #10 –
Quote from: geomm –
We completed the running of a 80' 6-3 romex dedicated line off of the 200 amp main panel on the house -- on Sunday. So, I have a 50 amp, 240 Volt box now that I plug my shore power cord into.
I ran four #6 wires for my 50 A outlet. The fourth wire went to ground in the main panel. My understanding is there should be a fourth wire from the ground connection in the socket to the ground in the main panel. I think that ground wire is the only connection from the chassis of the motorhome to earth ground. It should be in place for safety.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: 50 amp Wiring - Getting it right the first time.

Reply #11 –
Yes, J.D. -- the 6-3 wg also has that fourth ground wire that we attached to the earth ground on the main panel. Then we grounded the connection box, and that ground wire went to the socket where it brings ground into the Coach through the round pin on the shore power male plug.
Michael
1995 U300SE CAT 3176B Build # 4612 ("Marvin")
 

Re: 50 amp Wiring - Getting it right the first time.

Reply #12 –
Quote from: geomm –
Yes, J.D. -- the 6-3 wg also has that fourth ground wire that we attached to the earth ground on the main panel. Then we grounded the connection box, and that ground wire went to the socket where it brings ground into the Coach through the round pin on the shore power male plug.
^.^d ^.^d
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX