Residential Electrical Question

[mjah]

Here's a question for the ES home-electric gurus.

I'm installing a 240V baseboard heater in a new finished room in my basement, which of course requires a 2-pole breaker in the panel. My town code requires an AFCI breaker for this work. The 2-pole combination type AFCI breaker I picked up has a load neutral pigtail running from the breaker to the panel's neutral bus. And given that there's a "neutral" terminal in the breaker, the breaker seems to expect that the wiring I run will also have a neutral wire.

Fine, but -- simple question: Why have a neutral in a 240V line? My understanding is that there's no reason for a neutral in a 240V line: you have two hots 180 degrees out of phase with each other, and therefore there's no need to provide a separate line back to the panel; it's already there. So my plan is to run the two hots plus a ground -- no neutral necessary. And this mysterious neutral terminal in the breaker is ruining my plan.

Is there a different kind of 240V AFCI breaker which expects no neutral and therefore has no neutral terminal? Can I just ignore the neutral terminal and wire up the hots and ground? Or do AFCI breakers always require a neutral in the circuit? And in the latter case, WTF does a neutral even do in a 2-pole circuit?

[DeanCollins]

mjah, I assuming an AFCI is and Arc Fault breaker, that's required on everything in a bedroom. In the panel the neutral wire bar is essentialy the same as the ground bar.

It sounds like you want to run a 10/2 w/ground wire instead of a 10/3 wire.

[Johns Bass]

Here's a question for the ES home-electric gurus.

I'm installing a 240V baseboard heater in a new finished room in my basement, which of course requires a 2-pole breaker in the panel. My town code requires an AFCI breaker for this work. The 2-pole combination type AFCI breaker I picked up has a load neutral pigtail running from the breaker to the panel's neutral bus. And given that there's a "neutral" terminal in the breaker, the breaker seems to expect that the wiring I run will also have a neutral wire.

Fine, but -- simple question: Why have a neutral in a 240V line? My understanding is that there's no reason for a neutral in a 240V line: you have two hots 180 degrees out of phase with each other, and therefore there's no need to provide a separate line back to the panel; it's already there. So my plan is to run the two hots plus a ground -- no neutral necessary. And this mysterious neutral terminal in the breaker is ruining my plan.

Is there a different kind of 240V AFCI breaker which expects no neutral and therefore has no neutral terminal? Can I just ignore the neutral terminal and wire up the hots and ground? Or do AFCI breakers always require a neutral in the circuit? And in the latter case, WTF does a neutral even do in a 2-pole circuit?

There are different kinds of 240 - balanced and unbalanced. So yes you can have a neutral on a 240 line. On the ther hand - I have never heard of a 240 Arc Fault Breaker but I do not live where you do.

Quite frankly, an arc-fault in this instance does not make sense anyway unless this is some kind of plug-in device - which is what an arc fault is meant to protect. AF breakers are meant to protect from a spark or overload at the plugin - if the device is hardwired the breaker will protect it (unless the breaker is not sized to the circuit).

So A> I have not ever installed a baseboard with a neutral so installing an Arc fault would never work and anyone that would require one has no concept of AC theory

And B> Unless the device is a plug-in (has a cord-cap that goes into an outlet) the AFCI does not do anything anyway. It is designed for overloads of arc's (which would constitute an instantaneous overload) at an outlet - not at a hardwired device.

Basically - if your baseboard heater is wired directly to the breaker through the wiring in the wall without going through any kind of plug; then the Arc Fault interrupter is pretty much USELESS. It will not provide any more protection than a normal breaker would.

If your city needs a lesson in AC theory then have them give me a call. I have been doing electrical work long before Arc fault breakers (20+ years) were required for anything and helped the State of WA figure out exactly what they did and what they were good for.

[Larry]

Reasons to have a neutral.

The device isn't guaranteed to pull equal amounts of power from both lines. You clothes dryer, for example, may have 220V heating elements, but the controll panel and the light bulb inside the dryer run on 110. (Meaning, they're wired between one of the "220" lines, and the neutral.)

When an unbalanced load occurs, then the neutral wire will carry a current, equal to the difference between how much power each of the 110 lines is carrying.

If one of them is carrying 10A, and the other one is carrying 12, then the neutral will be carrying 2.

(The fact that the neutral carries the difference, rather than the total, is why the neutral doesn't have to be bigger than the hot wires. If the two hot wires have 20A breakers on them, then the most the neutral will ever carry is 20A. (If one leg is carrying 20, and the other is zero.))

Now, that said? Odds are really good that your baseboard heater consists of exactly one load: A 220V heating element. If it's one of those where the thermostat literally is a 220V switch, then there is nothing that can cause a differential load.

It might work, if this is the only thing you're hooking up.

But, why risk it? Frankly, wire is cheap compared to labor. (Even if it's only your labor.) You really gonna save enough money just by cheating on the wire, to justify the possible aggravation?

[SC_RedskinsFan]

You should not have to have an Arc Fault breaker on the heater because it is for dedicated use. The purpose of an Arc Fault is to have them on the recepticals.

Now as far as it having a neutral bar and not using it. A lot of things require a 240 GFCI breaker that do not have a neutral. Pool motors for instance. A motor does not need a neutral to run it, but the GFCI breaker will still work correctly even though nothing is hooked up to the neutral.

[DeanCollins]

My guess is this electric baseboard heater has a plug. Why else would the building department require and arc fault breaker? Cut the plug off and wire into the junction box and loose the expensive breaker.

[mjah]

Thanks for the replies so far, guys. Couple of details, per your questions and comments:

- This is a hardwired baseboard, with no receptacles or anything else on the circuit. Just the heater with its single element.

- The heater doesn't have a neutral on it as far as I can tell -- so I'm not even sure how I'd wire a neutral to it in the first place. I have no intention of cheating on the wire. I just can't see what the far end of the neutral would be connected to.

- The way it was explained to me is, it's possible to cause arcing in a hardwired device by driving a nail in exactly the wrong place, getting a break in the wire insulation, etc. These scenarios are largely implausible but certainly not impossible, so the city now requires everything to be AFCI except for bathrooms which must be GFCI. :whoknows:

[DeanCollins]

Sounds like the city is making a requirement that is not part of the national electric code.

I would ask them to show you the page in the code (national or city) that the requirement is in. Some times inspectors and plans examiners over reach by way of "interpretation".

Some of these interpretations are reasonable but many of them are not. I challenge these regularly and most of the time the official drops the requirement when I ask for the written code showing the requirement.

Last time it happened the gas inspector, while inspecting a new gas supply line in my laundry room, told us that we would have to provide a return air duct for the laundry room or cut a hole in the wall and install two AC wall registers so that the laundry room could breathe, apparently to prevent spent gas fumes from accumulating in the laundry room (carbon monoxide I guess). So I took the laundry room door hinge pins out and removed the door from the area, which provided about 15 sq/ft of venting . He then told me that I had to remove the other half of the hinge on the door frame because it showed "intent" to re-install the door. Even though I could've removed the 12 screws and the hinges from the frame in 30 seconds, I called up his boss (who made the call) and chewed him out, respectfully of course. In his argument, earlier about the venting of the room, he said that "he was only trying to enforce the "minimum standards". I told him that "interpretation" was not "enforcing the minimum standards". He grew tired of my circular argument and gave up. :pfft: