Hot water heater tripping post breaker

[CanTireGuy]

Hi,

2023 5.0 with a hot water heater element. When plugged into 30amp and I turn on the hot water heater the post breaker will eventually trip. Hot water will heat up and can be used but this is happened at different campsites. Only other thing on is the compresser fridge and maybe a couple lights. EMS says power is normal. I am assuming it's due to heater and fridge starting at same time. Is this normal? Troubleshooting? Any suggestions welcome.

Workaround is to use propane to heat water. Googling/board search has not found any answers.

Mike

 

[Selkirk]

Are you sure the power pedestal is a 30A service?

I believe the HW heater draws about 12A when active. The compressor fridge is 12V, so it will draw power from the converter (along with lights and battery charging). The EMS should display total AC current draw, If it indicates around 15A when the breaker trips I would suspect that the pedestal is only a 15A circuit.

If the pedestal breaker is confirmed to be 30A, but is tripping at indicated EMS loads significantly less than that, it could be a bad pedestal breaker or a loose connection between the power pedestal and trailer (perhaps an issue with the detachable with power cord or inlet at the trailer). There have been reports of loose connections where the inlet is wired into the trailer.

 

[CanTireGuy]

Thanks for the reply. Yes, need to check EMS... good point. I got it... use it.

HW 12 amps. Fridge... need to check on that load. Tripping happened at two campgrounds so I doubt both only had 20amp circuits. I will check for loose connections.

Mike

 

[John in Santa Cruz]

compressor fridges are maybe 60 watts when on (5 amps at 12V). thats 0.5 amps at 120VAC.

the water heater is purely resistive, so no 'surge' when it cycles on, you only get that with a heavily inductive load like an electric motor.

 

[TTMartin]

Be aware the WFCO 8955 converter can and often does draw 11 amps / 940 watts when bulk charging at its full 55 amp 12 volt DC output.

 

[John in Santa Cruz]

Be aware the WFCO 8955 converter can and often does draw 11 amps / 940 watts when bulk charging at its full 55 amp 12 volt DC output.

even 11A for the converter and 12A for the water heater shouldn't blow a 30A breaker. My experience with various converters and lead acid batteries is, they almost never come anywhere close to their rated charge output. Now, my PD4655L feeding my 412AH worth of Lithium batteries definitely outputs a steady 50A DC at 13.6-14V until the batts are fully charged, that's around 700 watts, around 6 amps AC.

 

[TTMartin]

even 11A for the converter and 12A for the water heater shouldn't blow a 30A breaker. My experience with various converters and lead acid batteries is, they almost never come anywhere close to their rated charge output. Now, my PD4655L feeding my 412AH worth of Lithium batteries definitely outputs a steady 50A DC at 13.6-14V until the batts are fully charged, that's around 700 watts, around 6 amps AC.

The 950 watts AC input is what is from the WFCO specs sheet. 700 watts would require 100% efficient AC to DC conversion which doesn't happen.

As far as tripping the breaker there are other AC loads on the circuit even if nothing else is being used. The EMS and the Transfer Switch both have electromagnetic relays that draw constant AC power when plugged into shore power. The microwave and TV both are parasitic. While I agree that 'shouldn't' be enough to trip a breaker. You have to remember breakers on power posts in campgrounds are just regular breakers that in most use cases might get physically switched off an on a half a dozen times in their entire lifetime, but, get physically switched on and off every couple of days as people rotate through the campsite. That likely reduces the actual current required to trip them.

 

[Gingerdog]

The shorted out heating element in the tank ( dead short ) maybe the cause.