seperate panel to feed electric furnace

[slick 50]

We have been doing this for years but now an inspector that we do not know turned us down for this.

When an electric furnace requires (3) 60 amp 240v circuits and (1) 30 amp 240v circuit, we would mount a 100 amp MLO panel next to the furnace and feed it from the main panel with 100 amp SEC....just 2 hots and a ground, no neutral since this panel is for 240v equipment only and simply acting as disconnects for the equipment ( furnace ).

The inspector says this needs to be treated like a subpanel and needs a neutral ran to it as well which needs to be isolated from equipment ground.

Where in the NEC can I find this particular installation? I can't find it in feeders or sevice disconnects. ANY HELP WILL BE GREATLY APPRECIATED!:-?

 

[Dennis Alwon]

A neutral only needs to be run to the building with the service not with a feeder. Ask him to show you where it is-- it is not there. You often see a 3 phase panel that only has a few circuits and 3 phase loads.

 

[Dennis Alwon]

If I decide to use a 2cir breaker panel as a disco for say, a water heater, would I need a grounded conductor to that panel. I don't think so.

 

[calhaz]

I think the inspector may be looking at 215.2 A as a requirement for a grounded conductor. Because the wording does not say "Where needed" or " Where Required". It could lead to requiring a grounded conductor

 

[LarryFine]

The inspector says this needs to be treated like a subpanel and needs a neutral ran to it as well which needs to be isolated from equipment ground.

He's wrong about needing a neutral to a panel that does not serve any line-to-neutral loads.

I wonder, though, how a 100a feeder and panel can supply three 60a and one 30a circuit?

 

[slick 50]

He's wrong about needing a neutral to a panel that does not serve any line-to-neutral loads.

I wonder, though, how a 100a feeder and panel can supply three 60a and one 30a circuit?

The elements never run all at once. They oscillate similiar to a water heater so elements dont burn out

 

[Dennis Alwon]

The elements never run all at once. They oscillate similiar to a water heater so elements dont burn out

I have never seen that. So you may have a 20 kw unit with only 10 or 12 kw going at one time. Cool.

 

[slick 50]

I have to meet the inspector today and I am going to just explain that this panel is simply equipment disconnects as well as OCPD's. I will point out 424.19 to him and see if he goes for it.

 

[Dennis Alwon]

I have to meet the inspector today and I am going to just explain that this panel is simply equipment disconnects as well as OCPD's. I will point out 424.19 to him and see if he goes for it.

I don't think that article will help. Ask him to show you the article that applies and then show him 200.2 where it state premise wiring shall have a grounded conductor. All that means is that a grounded conductor needs to be brought in at the service and no further than that.

 

[slick 50]

Thanks guys!

 

[AV ELECTRIC]

Let him know that this panel is dedicated to the heating system If a neutral is run people may want to use it to supply other circuits and you dont want that.

 

[neutral]

The elements never run all at once. They oscillate similiar to a water heater so elements dont burn out

If only one heater at a time is energized why would you need 3 circuits? How do they determine which element is energized and for what duration? Could you list the mfg. and model number? At what fequency do the water heater elements oscillate?