20Amp circuit to Hurricane cabinet

[Mike Groves]

When I replaced the Hurricane and hot water heater in my 1999 Beaver Marquis, the guys at ITR used the existing 20amp circuit to that cabinet to power the 1500W filament in the OASIS Combi they installed for me.  That worked for me up until recently when I noticed it was no longer working.  I "buzzed it out" and my meter was reading much less than 120V or 110V.

So, what I did was run a line from the existing outlet in the next cabinet (one that is supposed to be perhaps for a freezer) to the Combi and after completing that wiring I was up and running again. 

From time to time, even though I've solved the problem, I wonder why the 20amp circuit doesn't pop or anything, rather it just shows low voltage.  Is it possible for a circuit to be lower in voltage, what would cause that?

The other possibility is that perhaps the circuit was ok, and for whatever reason the Combi didn't function properly and that though a coincidence I hooked up my "solution wiring" and it worked.  Perhaps the system just needed a reset or the like.  This would also mean that it was my meter that gave an invalid reading or I was not using it correctly.

I guess my question is, can a simple 120V line "lose" voltage or in some way fail, and what would be possible reasons (other than operator error)?  Has anyone experienced this?  I should note that to test the output, I was using the generator, but I first noticed that the element wasn't working while parked and under shore power.

Thanks in advance for any ideas.  Obviously next time I visit the storage lot, I am going to again connect that 20amp circuit and turn on the generator to see if the Combi again works, but I wanted some ideas in case I've actually been right about the failure of the 20amp service.

Mike

[Steve Huber Co-Admin]

Mike,
If the connections are good, the only way you could see considerably less voltage than 120 is that the load is drawing a lot more current than the circuit is designed to  supply, but that should pop the breaker of fuse. I suspect what you saw was due to a poor ground either in the circuit or, more likely,  in the meter hook-up. If you see this again, measure between hot (black wire) and ground (green) and between hot and neutral (white). You should see 120v in both cases.
If the circuit is still hot, check the voltage now w/o a load per above. That will tell you if you had a bad load/meter connection or if the problem is in the source.
Steve

[Mike Groves]

Thanks Steve,

I will also meter a known outlet just to make sure I understand my meter's output.  I will probably just hook up the Combi to the 20A wiring first to see if I still get no power to the Combi. 

Seems that I went back to the breaker, and put the meter to the black wire output and to the ground bar and did get 120V (or so), then checked at the other end, and nothing, but this was done last fall so I may not be remembering accurately, so I'll just have to do everything again.

Mike

[Gerald Farris]

Mike,
Apparently they used the circuit for your original hot water heater to power the electric element in your new heating unit. I think that the Seaward water heater had a 1200 watt element, so the 1500 watt element in you new heating unit should work fine on that circuit. The low voltage under a load would indicate a bad connection at a junction box, base plug, or breaker most likely.

Gerald 

[Mike Groves]

Thanks Gerald,

What is a "base plug"? 

I am assuming low voltage under load, but the only voltage I measured was when I got into the junction box, disconnected all three wires, left them hanging out of the box, then turned on the generator, waited for it to come online, then used my voltmeter between black + and white - then black + and green - to see if I was getting voltage.  If I remember correctly my meter showed about half of what I expected to see, but I'll hook it up again and see what happens now.  I have removed the wiring from the junction box in the cabinet so that nothing will be touching anything except the 3 wires will be reconnected to the Combi 120V connection wires.

I am hoping I just had some sort of weird coincidence of things which led me to believe the circuit was faulty.  The only thing different from the last time it worked to when it stopped working was I had more insulation in cabinet and it would have gotten warmer in there.  I'd also blocked off the original air intake in the right (towards front of the coach) panel of the cabinet.  I suppose it was for the hurricane system, but the Combi breathes through the same area as the exhaust, and there was a lot of dust coming in that meshed opening.

Thanks,
Mike

[Fred Brooks]

      Hi Mike,

Gerald and Steve are right on task. Typically 120 volt problems don't fix themselves but can elude you with false readings on your meter. From my experience, circuits that have "high amperage or wattage" put a serious demand on any connection between the circuit breaker and the "load". The most consistant failure I have found is a melted wire nut in a J-Box. It usually starts out the wire nut is NOT taped with electrical tape and vibration and or poor assembly causes  the nut to loosen. loose connections cause resistance. Resistance causes heat and the rest is obvious. The false reading is what is left of the connection which is voltage mixed with resistance but  won't carry a load anymore. This is why they put these connections in metal "J-Boxes to contain the potential fire.
    Check the voltage again at the circuit breaker between the breaker output and the neutral white wire buss.
Then check the voltage at the wires you had originally connected to the hurricane. These votages should be within 1 or 2 volts with no load on them. If not, start tracing them backwards until you find a j-box. Hope this helps and please advise.    Happy Hunting!  Fred