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Mike, Master Electrician
Category: Electrical
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Experience:  Licensed Master Electrician - OnQ Certified Data Voice Audio Video Installer
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We are installing a 60 amp subpanel from a standard 200 amp

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We are installing a 60 amp subpanel from a standard 200 amp main panel, in our garage, for our RV. The main panel has the neutral and ground bonded together. I have read that the RV busses are not bonded. Does that make the subpanel incompatible with the RV? If it is incompatible, what is my best option? Most of the standard AC circuits on the RV are not working, and the onboard batteries are not charging properly.

Additional info: VOM readings: 110vac between w-x and between w-y, 220vac between X-Y; 14-50R outlet; 6/3 wire from subpanel via a 50 amp feeder breaker in the main panel.
Hi, can you verify your meter readings for me? You should be reading 120V and 240V... 110 and 220 are generic "terms" used to describe 120V and 240V but you would hardly ever get an exact reading of 110 or 220, or 120 or 240 even for that matter. What are you using for this voltage test? What are you using as a basis for "AC circuits not working"? Are you plugging equipment in and it's not working? Or are you using a voltmeter to check for power? How did you make the connections with the 6/3 in the subpanel (which wire is connected where)?
Customer: replied 7 years ago.

Here is the subpanel:


It is currently on a 50 amp feeder breaker, therefore, we have the breaker on the GFI off. The 6/3 wire into the subpanel is wired exactly as the diagram on the door panel. Red/Red, Black/Black, White/White, and Ground/Ground.


Voltage meter readings - Set on 500V AC scale - x-y (R&B) 228 VAC; x-w (W-R/B 113 VAC; ground (G-R/B x 113 VAC. for diagram of outlet


AC behavior while connected to the active subpanel - Initially, all light switches, appliances, air conditioner, etc work as expected. A short time later, turning on a light switch for a DC light, slows or kills an active fan. Eventually, the air conditioner kicks off but its fan will still run a bit longer. The refridgerator will eventually shut down though the TVs will stay on.

Thanks for the additional information... how far is this subpanel from your main panel? What kind of wire did you use for the 6/3?

Edited by Mike on 6/1/2010 at 7:06 PM EST
Customer: replied 7 years ago.
36 Feet of 6/3 Copper thru the attic.
That voltage seems low... can you take a reading directly from the 50A breaker in the main panel? Take a reading from hot-to-hot (both terminals on the breaker), and then from each terminal on the breaker to the neutral bar.

Then, you mentioned previously that voltage from x-y was 228 VAC and x-w was 113. How about from y-w?

Edited by Mike on 6/1/2010 at 7:25 PM EST
Customer: replied 7 years ago.

R-B 50AMP main panel= 228vac





Ok... I don't think you have an electrical problem here, at least on the supply side of things. In regards XXXXX XXXXX question about the neutral/ground bonding, that is a non-issue here. Things are perfectly compatible. The neutral and ground is bonded at first point of disconnect coming from the utility. Every subpanel after that point should have a separate neutral and ground, as should your RV subpanel. So that is a non-issue here. You appear to have everything connected correctly. The voltage is borderline. You want at least 114V to within recommended guidelines, but you shouldn't start to see any problems until to dropped to at or below 110 or so, in most cases. That coupled with the fact that you have this voltage directly at the main panel tells me your voltage is fine. Otherwise you would be having problems with equipment in your house. You may want to double check all your connections to the breakers in both panels, as well as the 50A receptacle to make sure everything is tight, but other than that, your wiring seems to be perfectly fine which points to an issue with the RV itself. We have an RV category here. You may want to post a question there regarding the RV wiring.

Edited by Mike on 6/1/2010 at 7:49 PM EST
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