40A fixed space heating equipment

[marmathsen]

Can I Install a 40A branch circuit for a heater in a dwelling?

Here's the situation:
In a single family dwelling we have a 6000 watt dual element infrared heater on a deck that is currently fed with 8 AWG conductors and a 40 amp circuit breaker. Article 424.3(a) states that a single heater can be any VA or wattage, but also states that two or more outlets shall not be fed by a circuit larger than 30A. Article 424.3(b) requires heating circuit conductors, panels and overcurrent protection to be rated at 125% of the load, but Article 210.20(a)exception permits sizing the panels and overcurrent protection at 100% if the equipment is rated for 100% operation.

My inspector first said that the conductors were too small. I responded saying that it is 8 AWG wire. He then said, that the switch being used to control the heater was too small. I responded saying that the 20A switch was listed for this use by the manufacturer (two switches each control 1 phase of each of the 3000 watt elements and should only be required to have a 15.625A rating). He asked for documentation proving that. I sent it, he escalated it to the lead Seattle inspector, the lead inspector called the manufacturer. The lead inspector eventually settled on the fact that he felt that the dual element heater is considered 2 outlets (I don't agree, do you?) and 424.3(A) limits the circuit to 30A.


So to summarize:
Can I have a 40A branch circuit feeding a 6000 watt heater in a residence?
-if not then-
Can I use a 100% rated circuit breaker and enclosure and install a 30A circuit breaker?

-also-
Are individual element connections on one heating appliance considered individual outlets, or is it one outlet that supplies one heating appliance?

 

[GoldDigger]

-also-
Are individual element connections on one heating appliance considered individual outlets, or is it one outlet that supplies one heating appliance?

Where the wiring which is part of the heating appliance (UL listed, I presume) meets the fixed building wiring is the location of the outlet.
If the switches in question are inside the heater and fed from one set of wires, then the inspector has no ground to stand on.

If somebody took two individual 3600W heaters and built them into a cabinet and provided two switches, it might be two outlets, especially if two separate runs of building wire went to the two switches or the wiring after the switches was building wiring.

 

[marmathsen]

especially if two separate runs of building wire went to the two switches or the wiring after the switches was building wiring.

To clarify, the switches ARE attached to the building wiring. It is a stack switch that controls the conductors that feed through one conduit to the appliance.

On that premise a ceiling fan with one switch for the fan and one switch for the light would be two outlets also. Or even more to the point, a receptacle with one switched outlet and one constant hot outlet would be 2 outlets. Correct?

 

[GoldDigger]

To clarify, the switches ARE attached to the building wiring. It is a stack switch that controls the conductors that feed through one conduit to the appliance.

On that premise a ceiling fan with one switch for the fan and one switch for the light would be two outlets also. Or even more to the point, a receptacle with one switched outlet and one constant hot outlet would be 2 outlets. Correct?

Pretty much. One could even argue that a duplex receptacle is two outlets.

 

[marmathsen]

So then does any one see a reason that I couldn't use a 100% rated overcurrent device?

 

[infinity]

So then does any one see a reason that I couldn't use a 100% rated overcurrent device?

Where would you find such a device for a dwelling panel? I don't think that they were even made in the form factor that you've mentioned.

 

[edlee]

Can I Install a 40A branch circuit for a heater in a dwelling?

Here's the situation:
In a single family dwelling we have a 6000 watt dual element infrared heater on a deck that is currently fed with 8 AWG conductors and a 40 amp circuit breaker. Article 424.3(a) states that a single heater can be any VA or wattage, but also states that two or more outlets shall not be fed by a circuit larger than 30A. Article 424.3(b) requires heating circuit conductors, panels and overcurrent protection to be rated at 125% of the load, but Article 210.20(a)exception permits sizing the panels and overcurrent protection at 100% if the equipment is rated for 100% operation.

My inspector first said that the conductors were too small. I responded saying that it is 8 AWG wire. He then said, that the switch being used to control the heater was too small. I responded saying that the 20A switch was listed for this use by the manufacturer (two switches each control 1 phase of each of the 3000 watt elements and should only be required to have a 15.625A rating). He asked for documentation proving that. I sent it, he escalated it to the lead Seattle inspector, the lead inspector called the manufacturer. The lead inspector eventually settled on the fact that he felt that the dual element heater is considered 2 outlets (I don't agree, do you?) and 424.3(A) limits the circuit to 30A.


So to summarize:
Can I have a 40A branch circuit feeding a 6000 watt heater in a residence?
-if not then-
Can I use a 100% rated circuit breaker and enclosure and install a 30A circuit breaker?

-also-
Are individual element connections on one heating appliance considered individual outlets, or is it one outlet that supplies one heating appliance?

Is it wired to the manufacturers instructions, i.e. do they recommend a 40a circuit, #8 cu and two switches? If so , I would say the inspector is wrong.

If they insist on something else, why don't you put a little subpanel at the end of your 40a circuit, install two 20a 2-pole breakers and use them as the switches.

 

[marmathsen]

Where would you find such a device for a dwelling panel? I don't think that they were even made in the form factor that you've mentioned.

I've been quoted some Square D products. HDL26030C Circuit Breaker, and a J250S Panel.

These are not typically for a dwelling but the Square D engineers can't find a reason I can't use it.

 

[marmathsen]

Is it wired to the manufacturers instructions, i.e. do they recommend a 40a circuit, #8 cu and two switches? If so , I would say the inspector is wrong.

If they insist on something else, why don't you put a little subpanel at the end of your 40a circuit, install two 20a 2-pole breakers and use them as the switches.

The manufacturer lists the switches as a means to control the elements. They don't list OCPD size or conductor size. That's up to me to figure out.

The subpanel is one option. Yes that would work, but it would require rewiring everything on the deck and a subpanel on a very nice view deck. In spite of the fact that the 100% setup is $530 is would still save me more time and money than a subpanel on the deck.