[Kaffeene]

I frequently install Infratech electric patio heaters. Usually I install with 240V switches or Infratech relay panels controlled by smart switches.
They make a single or dual contactor panel that can be controlled by switches on a separate circuit or use smart switches to control the heaters.

They specify a maximum wattage of 6KW for each contactor relay. If I use 2 - 240V 4KW heaters (1 on each contactor) with 10awg wire to each heater, they specify a 42Amp main feed for the contacotr panel, however there is no individual overcurrent protection for each 4KW heater wiring. I have short circuit & ground fault protection provided by the 42A main feed circuit breaker.

How is this safe or approved to use in this way?

 

[CAUSA]

Does it have a UL sticker?
Note: 2 and 4 in the notes.

Are you using the manufacture high temperature whip?

If UL approved and it has to be inspected, since as the installer you pulled the permit?

Install as the manufacture instructions.

 

[Kaffeene]

Infratech says it's UL approved. And it will be inspected, however they don't always look at every detail and just expect me to install correctly.
I just want to make sure it's safe and each individual heater wire has over current protection. Technically each 4KW heater wire is not a separate circuit.
45A or 50A breaker & #8 wiring feeds it then it's #10 to each heater on the contactor. Maybe the contactor has integral thermal protection up to 6KW, but that still doesn't necessarily protect the #10 for overload, unless part of the UL approval determined that each heater will never exceed it's KW rating.

 

[CAUSA]

So, install as per manufacturer instructions.

Use the supplied porcelain marretts. High temp fibreglass tape if needed.

It is a resistance heater. So only way for high current, is a bolted fault to ground or phase to phase.

Resistance heaters when failing, the tungsten filament burns open. I have seen the filament burn through to ground but the main OCP shut the system down as designed.

I would be more worried of combustible materials on the wall or close to the heater mounted on a wall or ceiling.

Your main feeder is G fault and Arc fault protected.

Just remember if you modify the panel you change the UL rating (technically).

Contact the manufacturer with questions and see if there is a retrofit for protection on the 4K heater conductors.