Air handler circuit question

[byoungblood]

For context, I live in Virginia.

My air handler in the basement is on a 100A breaker, however the air handler (with electric aux heat) is rated at about a 50A load. The air handler itself is directly protected by 60A circuit breakers located on the unit itself. I presume that the old unit (replaced before I owned the home) may have had a higher ampacity requirement than the unit currently installed.

I would like to have a 240v, 20A outlet down in my basement, unfortunately it is located on the opposite end of the house from the panel so running another circuit down there is likely to be cost prohibitive. Main panel is in the garage which is on a slab, all of the existing wiring runs up and over the garage, and the circuits to the basement run down an interior wall on the other side of the garage where the crawl space opens up.

Anything in code that prohibits installing a sub panel downstairs on the existing 100A circuit, putting the air handler on a 60A breaker and then adding a 20A breaker for my outlet?

 

[Innovate1]

Is it a 4 wire run to the air handler? You need both a neutral and a ground wire and you may not have a neutral for a 240V unit. If that is good I don't see why not. A sub panel would be a lot cheaper and less work than running wire back to the main panel.

 

[byoungblood]

No, only two hots and a ground. As it would only have 240v circuits, the neutral isn't needed. I have no issues with the 120v wiring down there.

 

[alfredeneuman]

Is it a 4 wire run to the air handler? You need both a neutral and a ground wire and you may not have a neutral for a 240V unit.

He wants a 240 outlet......

 

[wyliesdiesels]

Is it a 4 wire run to the air handler? You need both a neutral and a ground wire and you may not have a neutral for a 240V unit. If that is good I don't see why not. A sub panel would be a lot cheaper and less work than running wire back to the main panel.

No neutral needed. It’s 240v loads only

 

[Innovate1]

He wants a 240 outlet......

Missed that detail. Although some 240 receptacles have a neutral conductor so just saying 240V doesn't automatically mean no neutral.

 

[Terry D]

What size wire is feeding the air handler

 

[byoungblood]

What size wire is feeding the air handler

#2

 

[Terry D]

When you say the air handler is protected by 60 amp breakers, is there 2 of them. If that is the case, are you sure it is only a 50 amp load.

 

[sparky 1971]

Missed that detail. Although some 240 receptacles have a neutral conductor so just saying 240V doesn't automatically mean no neutral.

If it needs a neutral it is referred to as a 120/240.

When you say the air handler is protected by 60 amp breakers, is there 2 of them. If that is the case, are you sure it is only a 50 amp load.

I bet it has two 50 amp heat strips.

 

[Terry D]

I bet it has two 50 amp heat strips.

That's what I'm thinking. Probably needs the whole 100 amp for the furnace

 

[Innovate1]

If it needs a neutral it is referred to as a 120/240.

And we know that everyone here always uses the complete technically correct names for everything.

 

[alfredeneuman]

And we know that everyone here always uses the complete technically correct names for everything.

as in 110/220?

 

[Innovate1]

220, 221. Whatever it takes.

 

[alfredeneuman]

Although some 240 receptacles have a neutral conductor so just saying 240V doesn't automatically mean no neutral.

The only thing I've ever run into (in 45+yrs) that took a 20A 120/240 recp, was a large copying machine.
(Which I would not imagine being in a basement)

 

[Norcal]

The only thing I've ever run into (in 45+yrs) that took a 20A 120/240 recp, was a large copying machine.
(Which I would not imagine being in a basement)

While not normally found in residential, Hoshizaki 208-230V single phase ice machines require a neutral, the water pump & condenser fan is 115V. But agree that other then cooking equipment & clothes dryers a neutral is not normally required.

 

[byoungblood]

When you say the air handler is protected by 60 amp breakers, is there 2 of them. If that is the case, are you sure it is only a 50 amp load.

It is protected by 2 60 amp breakers, one on each 120v leg. Main panel has a 100A tandem feeding the circuit.

 

[sparky 1971]

It is protected by 2 60 amp breakers, one on each 120v leg. Main panel has a 100A tandem feeding the circuit.

Confusion has set in. Will you please post a picture of the breaker(s) that are in the furnace. If it is one 60 amp 240 circuit, it should have one 60 amp two pole breaker. Not two single pole breakers. Maybe the climate in VA is gentle enough to only need one heat strip, but every electric furnace around here has two, which means two 50 or 60 amp breakers for the furnace.

 

[PoorUB]

220, 221. Whatever it takes.

 

[alfredeneuman]

But agree that other then cooking equipment & clothes dryers a neutral is not normally required.

...and dryers or ranges do not take a 20A circuit

 

[mike93lx]

Is the #2 wire aluminum or copper? If aluminum, you will have to switch the breaker in the main to 90a as #2 isn't rated for 100a.

If the unit really has 60a breakers in it, then I don't see how it could draw 100a anyway. Worst case, the breaker in the main pops when the heat is on full tilt and you are using your 240v receptacle.

 

[wyliesdiesels]

And we know that everyone here always uses the complete technically correct names for everything.

proper use of technical details is important in this field

 

[Norcal]

...and dryers or ranges do not take a 20A circuit

Was only going by neutrals being required.

 

[ycgoat]

I would reccomend looking at the FLA rating on the name plate of the AHU to verify what it needs, vs relying on what you see inside the unit.

 

[byoungblood]

Confusion has set in. Will you please post a picture of the breaker(s) that are in the furnace. If it is one 60 amp 240 circuit, it should have one 60 amp two pole breaker. Not two single pole breakers. Maybe the climate in VA is gentle enough to only need one heat strip, but every electric furnace around here has two, which means two 50 or 60 amp breakers for the furnace.

Yes, it came from the factory with two single pole breakers, one on each hot leg.
H
It keeps up well enough in the winters here, even down into the upper single digits. But I don't try to keep the house at 70+ degrees either.

 

[sparky 1971]

Yes, it came from the factory with two single pole breakers, one on each hot leg.
H
It keeps up well enough in the winters here, even down into the upper single digits. But I don't try to keep the house at 70+ degrees either.

If that truly is the case, and I have no reason to doubt you, there should be no problem with the subpanel and the 20 amp 240 volt outlet. You should probably label the panel 240 volt only, no neutral. You are probably missing a tie bar that connects the two breaker halves together. I'm picturing a Siemens or GE two pole, still common trip, but you can't turn both legs off simultaneously without the handle tie.

 

[Terry D]

Yes, it came from the factory with two single pole breakers, one on each hot leg.
H
It keeps up well enough in the winters here, even down into the upper single digits. But I don't try to keep the house at 70+ degrees either.

We need pictures. Like sparky said, your tie handle may be missing, although they do make 60 amp single pole breakers. If that is the case, then you have a 10KW furnace. Why someone ran a 100 amp circuit for it is to your advantage. You should be able to install a sub panel with no problem, It will just be for 240 volt loads since no neutral is present.

 

[byoungblood]

If that truly is the case, and I have no reason to doubt you, there should be no problem with the subpanel and the 20 amp 240 volt outlet. You should probably label the panel 240 volt only, no neutral. You are probably missing a tie bar that connects the two breaker halves together. I'm picturing a Siemens or GE two pole, still common trip, but you can't turn both legs off simultaneously without the handle tie.

It has me scratching my head too. I'm looking at the schematic and it shows that the breakers are supposed to be common trip. Guess I'll track down a tie bar for them.

 

[sparky 1971]

It has me scratching my head too. I'm looking at the schematic and it shows that the breakers are supposed to be common trip. Guess I'll track down a tie bar for them.

What kind of breaker is it (are they)?

 

[byoungblood]

What kind of breaker is it (are the

Square D series 3, type QOU.

I looked at it again and the light turned on. It needs the entire 100A for the air handler and heat. I was expecting to see a tandem breaker but these are two pole and tied together internally.

 

[sparky 1971]

I bet you have (2) two pole 60 breakers. QO's only have the handle on one half of the breaker, but it will still operate both halves of it with a single throw off or on. It's what I suspected, and the reason I asked for a picture in post #18.

 

[byoungblood]

I bet you have (2) two pole 60 breakers. QO's only have the handle on one half of the breaker, but it will still operate both halves of it with a single throw off or on. It's what I suspected, and the reason I asked for a picture in post #18.

That's exactly what I have. I've been working on installing a vanity and finally got around to taking the pictures this morning.

Now the main breaker to that circuit keeps nuisance tripping. No obvious overloads (I compared the voltage at the panel to that present at the air handler, they're within two volts of each other) but there is a distinct buzzing/humming coming from the breaker itself, so off to buy a replacement.

 

[sparky 1971]

That's exactly what I have. I've been working on installing a vanity and finally got around to taking the pictures this morning.

Now the main breaker to that circuit keeps nuisance tripping. No obvious overloads (I compared the voltage at the panel to that present at the air handler, they're within two volts of each other) but there is a distinct buzzing/humming coming from the breaker itself, so off to buy a replacement.

It's more than likely a bad breaker, but checking for voltage won't tell you a whole lot about why a breaker is tripping. You want an amperage reading. Unfortunately, most of the meters that homeowners wind up with don't have that function.

 

[byoungblood]

It's more than likely a bad breaker, but checking for voltage won't tell you a whole lot about why a breaker is tripping. You want an amperage reading. Unfortunately, most of the meters that homeowners wind up with don't have that function.

I've got a Fluke 87V and Simpson 260 (I work on old tube radios and amps amongst other things) I just don't have a shunt or clamp capable of measuring that much current, as I seldom need to measure more than 5 amps.

It isn't an instant trip, only happens when the aux heat has been running for a while. Only other likely fault could be the heating elements, but I find it a bit odd that the main is tripping before the one on the handler if that is the case.

 

[sparky 1971]

I've got a Fluke 87V and Simpson 260 (I work on old tube radios and amps amongst other things) I just don't have a shunt or clamp capable of measuring that much current, as I seldom need to measure more than 5 amps.

It isn't an instant trip, only happens when the aux heat has been running for a while. Only other likely fault could be the heating elements, but I find it a bit odd that the main is tripping before the one on the handler if that is the case.

Make sure take a look at the bus stab connection when you pull the old breaker out. If it's cooked, all you are doing is putting a bandaid on it and delaying the inevitable. If you have the breaker spaces available, move the new 100 amp breaker to a fresh set of stabs.

 

[byoungblood]

Make sure take a look at the bus stab connection when you pull the old breaker out. If it's cooked, all you are doing is putting a bandaid on it and delaying the inevitable. If you have the breaker spaces available, move the new 100 amp breaker to a fresh set of stabs.

Will do. I've got some room in the box.