20 amp 240v continuous load calculations

[Chuck B]

I am installing three (3) digital wall heaters in my cottage on a 240v 20 amp circuit. My calculation at 80% is 3,840 Watts.

However my plan is to install (2) 1,600 volt and (1) 800 volt heaters (wall units with built in thermostats) which places me at 16.666 amps and a 4,000 watt draw on the 20-amp circuit.

It is likely all heaters would run simultaneously in my northern Michigan cottage.

Does the additional .6666 amps over the 80% 16 amp calculation present a safety or CB trip problem in practice.

Thanks.

 

[WorthFlorida]

You'll need two circuits @ 20amps each or a (1) 30 amp breaker with 10 gauge wire. This link explains it perfectly. You're at 4000 watts, not 3850 watts. There is no 80% factor on the load.

https://www.king-electric.com/pdfs/helpful-hints-sizing-chart.pdf

 

[Sponsor]

 

[Jadnashua]

On items that can be expected to be on continually, generally, the 80% rule does apply. It's actually calling for the circuit to be 125% of the load if it could be continuous for 3 or more hours, which when you look at it another way, equals 80%.