Overcurrent size for over range microwave

[Mr.electric]

Hello, just wondering if overcurrent protection for a dedicated over range microwave circuit is held to the rule of 422.11(E)(3). Microwave is 1800 watt rating. Should I be taking 150% of 1800 watts. I always put these on dedicated 20 amp circuits but I was just wondering if this rule applied.

 

[LarryFine]

If you mean a 25 or 30 amp circuit, wouldn't you need an incompatible receptacle?

 

[augie47]

Note the requirement in 422.11(E)(3) is a "not exceed" value, not a minimum requirement.
Couple that with 110.3(B) and you will see most microwave manufacturers call for a 15 or 20 amp circuit,
That and, as Larry points out, the appliance likely comes with a 15 or 20 amp plug so your receptacle and overcurrent device would need to match.

 

[Mr.electric]

Makes sense. I was looking at it as a minimum if over 13.3 amps. The minimum would be 1800W/120V= 15 amps assuming it was non continuous load. 422.13 calls for 125% rating of water heater, other than that I don’t see where 422 calls for anything more than 100% the rating of appliance. Would you say 150% max would be for nuisance tripping or 110.3B where the manufacturer would directly call for it?.

 

[infinity]

Makes sense. I was looking at it as a minimum if over 13.3 amps. The minimum would be 1800W/120V= 15 amps assuming it was non continuous load. 422.13 calls for 125% rating of water heater, other than that I don’t see where 422 calls for anything more than 100% the rating of appliance. Would you say 150% max would be for nuisance tripping or 110.3B where the manufacturer would directly call for it?.

15 amp circuit is code compliant.