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microwave circuit breaker

sccoast99
Explorer
Explorer
My old Dometic m/wave was rated at 13 amps on a 15 amp circuit breaker - came with FW unit when new some 13 years ago. No problem. But old microwave died.

Most (all?) replacement microwaves of similar size (including Dometic) want a 20 amp circuit breaker and my fifth wheel has 15 amp. I have been told not to change the circuit breakers in my FW by a trustworthy dealer. I found a LG microwave rated at 12.5 amps (and a suggested circuit breaker of 20 amps). I am not sure how to have a replacement microwave given my 15 amp circuit breakers.

Any body else faced with this dilemma?
2003 Sunnybrook 30RKFS
2003 Chevy Silverado 2500 Diesel, Allison Transmission
8 REPLIES 8

dougrainer
Nomad
Nomad
MEXICOWANDERER wrote:
Impossible to get a garbage grade 20-amp receptacle. I know of no brand of 20-amp receptacle that isn't "Spec Grade". Tighten the hell out of the receptacle wire screws. Then kill the power, and go check the tightness of all screws in the AC breaker panel.


MOST RV receptacles(excluding GFCI's) have NO screws and are press fit. Doug

MEXICOWANDERER
Explorer
Explorer
Impossible to get a garbage grade 20-amp receptacle. I know of no brand of 20-amp receptacle that isn't "Spec Grade". Tighten the hell out of the receptacle wire screws. Then kill the power, and go check the tightness of all screws in the AC breaker panel.

wa8yxm
Explorer III
Explorer III
Dometic Black Counter Top/Built-In Microwave with Trim Kit Description. Power Draw: 12.1 A ... Dometic: Model: DCMW11B.F: Size: 1.1 Cu. Ft. Cooking Power: 1000 watts:

If that helps 12.1 amps
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times

dougrainer
Nomad
Nomad
Some OEM's had recalls a few years ago on Microwave Oven plugs. They installed a 15 amp rated receptacle instead of a 20 amp rated receptacle that you plug the M/W into. The M/W will not pull more than 13 amps, but they had the receptacle on a 20 amp breaker and realized that they needed a 20 amp rated receptacle. Even a Home type M/w will not pull more than 15 amps. You will have no problem with any Microwave you install. Doug

myredracer
Explorer II
Explorer II
There is normally a label on appliances somewhere because it's a code/standard requirement. The owner's manual for a DCMW11B.F is here.

Manual says "The electrical requirements are a 120 volt 60 Hz, AC only, 20 amp. ". It also says AC power consumption is 1450 watts. 1450 watts equates to 12.08 amps at 120 volts. If you add a 25% safety factor, this equates to a wire & breaker size of 15.1 amps. Question is, is there a power factor to consider and do they round up to the nearest breaker required above 15.0 amps being 20 amps? I have never been able to find any info. on what the current draw is versus input voltage - does it drop in a linear fashion or? Is there an inrush current that necessitates a 20 amp breaker?

The NEC in itself does not regulate the appliance that is plugged into a general purpose receptacle. For example, the hair dryer we have in the TT is rated 1875 watts but the NEC doesn't require bathroom recepts. to be 20 amps. Interestingly, the MW in our TT is on a 15 amp circuit but it also supplies a recept. at the kitchen counter. Have never had a problem with a toaster & coffee maker on plus the MW (900 watt) at the same time.

Microwave ovens typically aren't on very long, though they can be on occasion. Circuit breakers don't trip the instant current rises above it's rating. They have an inverse time-current characteristic as in the graph below. You can have a small overload on a breaker and it can run for a long time. The higher the current, the sooner it trips. A 15 amp breaker running at 20 amps for ex. would hold for several minutes or longer. A clearer image of the graph is here.

I would say it would be fine on a 15 amp breaker. The worst thing that can happen is the breaker might trip on occasion. Do you know if the MW recept. is definitely on a dedicated circuit? You *could* buy a lo-cost clamp-on ammeter (HF) and see what the MW actually draws.

Should the #14 wire be too small, depending on your FW layout, it may be possible to run new #12 romex cable. I've done lots of wiring in the ceiling space and up & down cabinets in walls including #12 - just takes patience.

sccoast99
Explorer
Explorer
Thanks for input. Wire is #14 so I will stay with the 15 amp breaker

The Dometic microwave now being offered (DCMW11B.F) does not provide amps (nor input wattage), only output wattage. I called them but no success there. Anybody know what Dometic's current model amps are?

Some models on the market provide this information, others do not. Frustrating.
2003 Sunnybrook 30RKFS
2003 Chevy Silverado 2500 Diesel, Allison Transmission

KD4UPL
Explorer
Explorer
Any microwave that pulls less than 15 amps will work on that circuit. If it happens to be #12 wire (not likely) then and only then could you replace the breaker with a 20 amp.
I would pick out a microwave and install it. It will be fine.

westend
Explorer
Explorer
There are many microwave ovens that operate on less than 15 A. Circuit breakers are always sized to protect a given wire size. 14 AWG gets 15 A and 12 AWG gets 20 A breaker. Don't put a 20 A breaker on less than 12 AWG wire.
'03 F-250 4x4 CC
'71 Starcraft Wanderstar -- The Cowboy/Hilton