Electric Water Heater upgrade trips circuit breaker

[KJAir]

We recently purchased a 1976 27' Overlander, and have been busy getting things operational. The original Bowen 10 gallon Water Heater was leaking through pinholes on the bottom. We replaced it with an Atwood GC10A-4E 10 gallon dual gas/electric. The install went well with minimal sheet metal work to get the original SS door to fit. We just spent 2 nights camping with it and are very pleased with both the electric and gas options. The problem is that I wired it into the General Services 15 Amp Breaker(tapping off at the polarity light junction box which was located just above the unit). The breaker trips if there is anything else running besides the heater. I calculate this heater draws 12.7 amps(1400 watts/110 volts=12.7 amps). I don't see any other options, as the other 2 available breakers each have a high draw appliance(air cond, fridge). There is no room in the Main Panel for another circuit breaker, so can I add another Breaker Box for this circuit, or is it ok to increase my 15 amp general services breaker to a 20 amp breaker? By the way, it is our first Airstream and my wife and I are very excited! We have learned sooo much from these forums this past month.

[J. Morgan]

I say no to the 20 amp breaker unless the circuit is wired with 12 gauge wiring.

Does your box currently use the full width breakers or does it use the narrow breakers?

If wide, you can double the breaker capacity of the box by moving to the narrow style.

[KJAir]

I was not aware that narrow breakers were available. I do have the original 1" wide breakers, but to change the breaker style it appears the bus-bars will need to be replaced as well. Thoughts?

[Nuvite-F]

A separate breaker for the water heater would be nice if it wouldn't be too hard to run the wire for the new circuit.

An easier solution might be to replace the 1,400 watt heating element with something smaller. As I recall the electric heating element of our gas/electric water heater is only 600 watts and it works fine. If you need to heat water faster you can run the gas burner until it gets up to temperature.

[KJAir]

I found some Atwood literature that says this model was initially designed with a 1500 watt heating element, but downgraded it to 1400 watts(12.7 amps) to keep it below the 15 amp limit. Not much margin!

Changing to a lower wattage element would work, but I hate to drop the recovery rate. Our attraction to this model was to enable us to save our gas and use campground electricity instead. Running a new circuit will not be too difficult but I want to ensure I don't overload the 30 amp main this summer when the air cond, fridge, water heater and coffee pot are all on. I guess if I have to run the fridge or water heater on gas when the AC is on, that's just the way it is.

[J. Morgan]

Most buss bars in most boxes will accept narrow breakers of the same brand and type.

Some will only accept the two 1/2" breakers in one 1" unit though. Either way you should be able to double the circuit capacity of your existing box.

(Two circuit breakers integrated in one 1" package, where two breakers in one fit on one spot on a buss bar)

[Jammer]

Hello KJ

The water heater should have its own breaker.

If your breaker panel will not accommodate another breaker, then I would suggest that you replace the entire panel.

[KJAir]

Thanks for the advice everyone. While shopping for a suitable new panel, I found the narrow breakers that J. Morgan was describing. I removed the 15 amp Gen Service Breaker, and installed a dual 15 amp breaker(one for gen service, and one for my electric water heater). I ran 12 gauge wire from breaker to heater. Works great!

[J. Morgan]

Excellent!