RV electrical question

Status
Not open for further replies.
S

Stevenfyeager

Senior Member
Location
United States, Indiana
Occupation
electrical contractor
A customer wants me to diagnose a brand new RV electrical problem. Says a section of the RV lights do not work and range vent fan. RV is plumber into his house outlet. Under warranty but no dealer has no time to check it before their trip Monday. Any ideas ? Maybe a tripped gfci…? I have never worked in a RV. Are these lights dual AC/DC ? Thanks!
 
If it's a 50 amp 120/240 RV I'd make sure it's getting proper voltage from the source. If they have it plugged into a home outlet they are likely using an adapter.
 
augie47 said:
If it's a 50 amp 120/240 RV I'd make sure it's getting proper voltage from the source. If they have it plugged into a home outlet they are likely using an adapter.
Click to expand...
Thank you. I’ll check that. It is probably a large RV. Bought new and I doubt he has a 50 amp outlet, we will see tomorrow. ( he’ll likely ask us to add one) We’ve done his electrical work for years. (Always adding things or remodeling) He is wealthy and has two nice homes here, one on a lake. He says he is counting on me, since I’m ‘the expert’. I didn’t get to tell him I’d never worked on an RV.
He mentioned DC. I think when not plugged in, the battery provides DC. There is a transformer that changes everything to DC, correct?
 
Sounds like a missing line, i.e., it's receiving 120v instead of 120/240v. What type of receptacle is it plugged into?
 
Check the type of receptacle on the RV for NEMA type. I was looking to buy an RV (trailer) at one time, and the owner admitted he had looked at the receptacle and connected it to 240 volts. It was 120, and he blew out much of the equipment in it. It wasn't a good enough price, considering the damage.
 
Stevenfyeager said:
A customer wants me to diagnose a brand new RV electrical problem. Says a section of the RV lights do not work and range vent fan. RV is plumber into his house outlet. Under warranty but no dealer has no time to check it before their trip Monday. Any ideas ? Maybe a tripped gfci…? I have never worked in a RV. Are these lights dual AC/DC ? Thanks!
Click to expand...
To add to the confusion, a 30A RV is 120V and takes a single pole breaker. All loads are 120V.
A 50A RV takes 240V on a 2-pole 50A breaker. However, there is nothing in the RV that uses 240V. All loads are 120V. The reason for 2-pole is the loads are more evenly divided, and the main reason is the 50A RVs have two (2) A/C units. One unit on each leg of the 240V feed. You couldn't put two A/C units on just one 120V line, they have to be on separate 120V lines.

There are GFCI receptacles in bath and kitchen and maybe other areas like outside receptacles, the lights normally aren't on a GFCI circuit but you might check them and see if any are tripped.

As was mentioned, the customer may only be using a 120V outlet with an adapter. The 120V line that the lights and fan are on may not be receiving power. Also mentioned were the lights, some are DC for use on battery power. These usually have a switch right on the light itself.
You can go to the panel inside the RV and check voltage on each side of the panel and see if maybe one side is dead.
 
readydave8 said:
The RVs I've seen have separate DC lights
Click to expand...
Some RVs also have a battery-driven inverter for small incidental AC loads when there is no hookup and the generator is not running.
Or even a larger battery bank and a several thousand watt "converter" (inverter/charger).
It is a design decision based on the planned use of the RV.
But DC lights, including fixtures with both AC and DC elements, are pretty much universal, along with a DC driven water pump and a propane/electric absorbtion refrigerator.
 
Usually, all rv lights are 12v because you want them all to work when unplugged. The vent fan is probably also 12V. So get out your DC meter and start checking for where the voltage is and isnt.

This is based on knowledge from years ago, but things could have changed and they just invert everything to 120 VAC, but that seems inefficient and efficiency matters in an RV if you are boondocking (no hookups).

120v things are usually water and space heaters (to save propane), AC units, and things normally made 120v like tvs and microwaves. The fridge could be tri power - propane, 12v, and 120v.
 
As mentioned already, all of the lighting is 12v.

Could be a blown fuse. Could be a loose connector somewhere. You’ll need to find the 12v fuse panel and inverter. I’ve worked on several RV’s and they’re never in the same place.


Sent from my iPhone using Tapatalk
 
So far no good. The fuse blows. And even without the fuse, when we touch the wire it sparks. I’m learning there is no neutral, right? Only a hot and ground? We’re disconnecting each item one at a time to see if we can isolate it. It wasn’t the ceiling vent fan or two ceiling lights. We’ve disconnected them and still get an arc. thanks.
 
Stevenfyeager said:
Ran a temporary bypass hot wire from the fuse to each light and fan. They work fine. No spark, no blown fuse
Click to expand...
So you have a short to the frame of the RV somewhere after the fuse. I'd jumper an incandescent bulb into the fuse slot and observe when that light goes out while tracing the wiring and jiggling it to find the short. Insulation is apparently worn somewhere.
 
Or pull all fuses first... then check outputs, then use resistive tester. It always seems to be in the battery inverter compartment. I also found a problem at the trailer plug.. connector pins vibrated outwards towards the frigging flap cover... it was so simple, yet took a long, long time to find.
 
Thank you. We narrowed down the damaged area, between the fuses and first switches. Owner asked us to rewire as he is used to asking us to add or repair items in his two houses. I told him unfortunately we can't fish a new wire easily like we do for his house requests. If we start removing panels we would possible void the warranty I told him. Those wall panels didn't look easy to remove.
 
Status
Not open for further replies.
Top