Do I really need a 20-amp circuit for this?

[jeff48356]

For a bathroom fan/light/heater unit, the manufacturer's directions call for a separate 20-amp circuit. However, the heater is 1300 watts, fan 145 watts, and the maximum bulb wattage is 100, for a total of 1545 watts. Now, the only time it will be 1545 watts is IF a 100-watt bulb is used. I would personally never use one, but rather, a CFL which is only about 20 watts. This would put the entire unit below the 1500-watt limit for a 15-amp circuit.

Can I wire this with a 15-amp circuit as long as I only use a CFL in the light? Or would I still be required to use a 20-amp circuit?

 

[480sparky]

The instructions don't say you can use a 15a circuit if you install a CFL. They says the unit requires a 20a circuit.

Would you install a 20a circuit for an electric range just because you only use one burner at a time?

 

[iwire]

For a bathroom fan/light/heater unit, the manufacturer's directions call for a separate 20-amp circuit.

110.3(B) Installation and Use. Listed or labeled equipment
shall be installed and used in accordance with any instructions
included in the listing or labeling.

I think that pretty much puts a wrench in your thoughts.

This would put the entire unit below the 1500-watt limit for a 15-amp circuit.

1,500 watt limit?


If it is not a continuous load (and I do not think it is) 120*15=1800 watts

If it is a continuous load 1800*.8=1440 watts.

 

[electricg]

I always thought that heater units had to be calculated at a 125% of the rated load, they are considered continuous. This poster says this is a fan/light/heater unit with a total of 1545 watts without the 125% added in. This would be over 15 amp rated circuit when the 125% is added.

Even without the manufacturers instructions, he would still have use a minimum of a 20 amp branch circuit.

 

[Dennis Alwon]

I always thought that heater units had to be calculated at a 125% of the rated load, they are considered continuous. This poster says this is a fan/light/heater unit with a total of 1545 watts without the 125% added in. This would be over 15 amp rated circuit when the 125% is added.

Even without the manufacturers instructions, he would still have use a minimum of a 20 amp branch circuit.

In general the heat is required to be 125% but not the light & fan. All that doesn't matter if the manufacturer requires a 20 amp cir anyway and I believe the calc. would still be over 15 amps

 

[templdl]

For a bathroom fan/light/heater unit, the manufacturer's directions call for a separate 20-amp circuit. However, the heater is 1300 watts, fan 145 watts, and the maximum bulb wattage is 100, for a total of 1545 watts. Now, the only time it will be 1545 watts is IF a 100-watt bulb is used. I would personally never use one, but rather, a CFL which is only about 20 watts. This would put the entire unit below the 1500-watt limit for a 15-amp circuit.

Can I wire this with a 15-amp circuit as long as I only use a CFL in the light? Or would I still be required to use a 20-amp circuit?

Well, have you considered the cost difference between running #14 or #12? The the cost of a 15A and 20A breaker should be the some.
As such the additional cost of a 20A ckt should be a minor issue. I know that for ease of installation #14ga wire is much easier to work with. # 12 is much harder to dress and terminate and the there is the arduous task of trying to fold the into the box.

 

[acrwc10]

Well, have you considered the cost difference between running #14 or #12? The the cost of a 15A and 20A breaker should be the some.
As such the additional cost of a 20A ckt should be a minor issue. I know that for ease of installation #14ga wire is much easier to work with. # 12 is much harder to dress and terminate and the there is the arduous task of trying to fold the into the box.

This is the perfect time to use 12-4 NM as the switch leads, 1 neutral and 3 switch legs in one cable.

 

[iwire]

I always thought that heater units had to be calculated at a 125% of the rated load, they are considered continuous.

I honestly never thought of a heat / fan / light combo as space heating equipment but now that you mention it of course it is.

 

[templdl]

This is the perfect time to use 12-4 NM as the switch leads, 1 neutral and 3 switch legs in one cable.

Oh what punishment that would be sort of like drinking Drano or hitting you thumb with a hammer.

 

[iwire]

Oh what punishment that would be sort of like drinking Drano or hitting you thumb with a hammer.

We work with 12 solid all the time, it is not a problem.

I don't even find 10 AWG that bad if the NEC box sizing rules are followed and some thought is given about where the cables enter the box.

 

[mjf]

For a bathroom fan/light/heater unit, the manufacturer's directions call for a separate 20-amp circuit. However, the heater is 1300 watts, fan 145 watts, and the maximum bulb wattage is 100, for a total of 1545 watts. Now, the only time it will be 1545 watts is IF a 100-watt bulb is used. I would personally never use one, but rather, a CFL which is only about 20 watts. This would put the entire unit below the 1500-watt limit for a 15-amp circuit.

Can I wire this with a 15-amp circuit as long as I only use a CFL in the light? Or would I still be required to use a 20-amp circuit?

:slaphead: Yes.

Don't complicate the simple answer with calculations and such

 

[templdl]

We work with 12 solid all the time, it is not a problem.

I don't even find 10 AWG that bad if the NEC box sizing rules are followed and some thought is given about where the cables enter the box.

Yo DA man. I find that #12 is a pain to fold back into a box and get the devices secur and making sure that pesky bare EGC stays out of trouble.

 

[iwire]

Yo DA man.

Naw, it's just all in what each of us is used to doing.

Doing things like securing the box well, entering the box from one side only, not skimping on box size, using better grade devices etc. can make trim out much easier.

A lot of jobs we do want us to jump up to 10 AWG on 20 amp circuits when the one way circuit length exceeds 100'.

 

[templdl]

Naw, it's just all in what each of us is used to doing.

Doing things like securing the box well, entering the box from one side only, not skimping on box size, using better grade devices etc. can make trim out much easier.

A lot of jobs we do want us to jump up to 10 AWG on 20 amp circuits when the one way circuit length exceeds 100'.

That #10 reminds me the 20a ckt that I needed may have approached 100' was required to support 3000-4000w of amplifiers for an audio system. A 20a ckt was well oversized but I wanted to assure that the dynamics for the power requirements did not result in voltage drops resulting from current peaks. I wanted to assure that the voltage stiff for a system with (8) 15" sub's and (24) in wall 8" surrounds. It will knot your socks off.

 

[jumper]

I honestly never thought of a heat / fan / light combo as space heating equipment but now that you mention it of course it is.

IDK, I think that it is more of of an appliance IMO, the heater is only really intended to heat part of the space for a limited amount of time. It is not the primary source of heat for the bathroom.

 

[brother]

IDK, I think that it is more of of an appliance IMO, the heater is only really intended to heat part of the space for a limited amount of time. It is not the primary source of heat for the bathroom.

Interesting concept. When I think of a 'heating appliance' and when you read 2008 NEC article 422, most of those heating types of appliances deal with cooking units, or it's a water heater etc...
Central systems implies it falls under both articles.

Fixed electric space heating article 424 deals more with space heating, basically intended to heat an area for the comfort for people. I will say that bath/light/heater combo would fall more under 424 than the appliance article. ;-)

 

[Dennis Alwon]

IDK, I think that it is more of of an appliance IMO, the heater is only really intended to heat part of the space for a limited amount of time. It is not the primary source of heat for the bathroom.

Where does the code specify primary heat source. I have put the heater part on a t-stat in the past.

 

[Dennis Alwon]

Yo DA man. I find that #12 is a pain to fold back into a box and get the devices secur and making sure that pesky bare EGC stays out of trouble.

Never had a problem but I use 22 cu. in boxes

 

[growler]

Now, the only time it will be 1545 watts is IF a 100-watt bulb is used. I would personally never use one, but rather, a CFL which is only about 20 watts. This would put the entire unit below the 1500-watt limit for a 15-amp circuit.

Can I wire this with a 15-amp circuit as long as I only use a CFL in the light? Or would I still be required to use a 20-amp circuit?

This fan/light/heater was designed with a 100W max lamp acceptance. So it doesn't matter what size lamp you actually install.

There will be a little sticker on the fixture that states max lamp size 100W. The next person to change out the lamp may want a 100W lamp.

If you already have a 15 amp circuit ran to the bathroom then you can look for a fan/light /heater that is designed to work on a 15 amp circuit.

 

[growler]

Fixed electric space heating article 424 deals more with space heating, basically intended to heat an area for the comfort for people. I will say that bath/light/heater combo would fall more under 424 than the appliance article. ;-)

A fan/light/heater is just a space heater combined with a light and fan. Is there some difference between the heat of a ceiling mount fixture and say a wall mounted space heater?