Water Heater 110v Wires Arcing?

[Jedsmom]

We’re out in our ACE 30.1 for the first time in a couple of months, and when we fired up the hot water tank on 110v, we got an electrical smell so shut it down immediately.

Called Tom in Customer Service at Thor this morning & he couldn’t pull up the schematic for our rig’s electric. He suggested that there could be a junction box inside & right behind the hot water tank. We don’t think so, as there’s a closet and drawers right there. Could it be under the bed? We’re willing to do a little sleuthing to see what’s going on, and then will get a repair shop to take care of whatever’s melted.

Any other suggestions from our esteemed friends? Seriously, you all have been a wealth of knowledge over the last couple of years, saving us lots of frustration and money.

Thanks in advance!

[ArrrV]

Pretty common problem with Thor--the wires connecting the hot water heater to the 110 are not tight enough. Melted on mine. Check them out and tighten. Check that Thor used the right sized wire connectors as well.

[tnedator]

Originally Posted by ArrrV

Pretty common problem with Thor--the wires connecting the hot water heater to the 110 are not tight enough. Melted on mine. Check them out and tighten. Check that Thor used the right sized wire connectors as well.

What's the safest way to work on this? Just hitting the store toggle, or one of the batter disconnects in the battery bay?

[Beau388]

The water switch is 12 volt. The 120 volt relay is in an electrical box attached to the back-bottom of the Attwood water heater tank. It is located just under the access to change the electric heater element. To check the wiring, the generator should be off and the shore power disconnected. If the water heater switch is in the OFF position, there will be no electric current to the wires in the relay box. Thor plant 750 is notorious for not tightening the 120 volt wires to the relay sufficiently to allow proper operation. On my coach there is a panel under the bedroom drawers that is removed to allow access to the water heater bypass. This panel also allows access to change the electric heater element and to the relay.

[ArrrV]

Originally Posted by tnedator

What's the safest way to work on this? Just hitting the store toggle, or one of the batter disconnects in the battery bay?

To work on the hot water heater wire connections: Turn the circuit breaker for the hot water heater off at the panel. I also turned off the electric side of the hot water heater at the switch. No need to turn off power to the Coach.

[Bob Denman]

Were there any signs of damage from rodents nibbling on the tasty wiring harness?

[tnedator]

Originally Posted by Beau388

The water switch is 12 volt. The 120 volt relay is in an electrical box attached to the back-bottom of the Attwood water heater tank. It is located just under the access to change the electric heater element. To check the wiring, the generator should be off and the shore power disconnected. If the water heater switch is in the OFF position, there will be no electric current to the wires in the relay box. Thor plant 750 is notorious for not tightening the 120 volt wires to the relay sufficiently to allow proper operation. On my coach there is a panel under the bedroom drawers that is removed to allow access to the water heater bypass. This panel also allows access to change the electric heater element and to the relay.

On my ACE 30.3 that's where it is located as well. There is a panel under the drawer with a speaker mounted in it. Remove two screws and it comes out.

The tech was in there trying to check out why my front outlet wasn't on the inverter (he was tracing wires and junctions). He showed me the back of the hot water tank when he was in there.

[Jedsmom]

A follow-up to this issue:

We continued to use the propane feature for our hot water until we got home. We'd already scheduled a service appointment for an oil change, so just added a check on the 110 situation.

Sure enough, the wires were loose and quite charred. The hot water tank had to be pulled to access them, so I'm glad we didn't try to do anything while on the road.

It's been fixed, and we're good to go in for our next trip.