Electrical Question?

[Cozy439]

Blower fan went out in the wood burner. My model wood burner is discontinued from the maker so no OEM replacement. Secondary suppliers had knock-off models for $230ish. Reading the specification sticker, I typed that info in and found the current equivalent model from the fan maker - $58. It arrived yesterday and I hooked it up last night. I am at work now so I can not take/post pix. Here is the issue. Old unit was 2-speed HI-OFF-LOW, with a temp. sensor to turn it off and on, with an extension cord and plug. New model is 1-speed (listed as HI speed equivalent), no sensor and no cord/plug. I hooked up a cord/plug last night so wife had heat today. I can live w/o the 2-speed, we hardly ever used LOW speed anyways. Can I wire the old temp sensor into the new unit? When I took old one off, I opened it to get cord off to reuse. Temp. sensor was wired in to the WHITE wire. Is it just that easy? Rewire the new unit in-line with the white wire? I am no electrician. I can rewire anything where I am given and can see a diagram. But I know my limitations well enough to know its better to ask for help then to burn up a motor or the house. All help is welcome. Thanks.

 

[churchmouse]

Those cheap fan units are a crap shoot for reliability so I hope you have good luck with it.
Yes, you can do what you are thinking about.

 

[Cozy439]

The unit is from the maker of the original and it lasted 16 yrs. Same casing, same bolt pattern to mount. Hope this one holds up too. I figured I was good to go on the wiring, but feel better asking. Thanks

 

[churchmouse]

The unit is from the maker of the original and it lasted 16 yrs. Same casing, same bolt pattern to mount. Hope this one holds up too. I figured I was good to go on the wiring, but feel better asking. Thanks

Those units are all outsourced off continent now. I put a blower in the gas log fire place and researched who made what and where. I paid a bit for it but hope it will last.

 

[17 squirrel]

Yes, its just that easy..
Alot of times you can source a exact replacement from Industrial supply houses like Grainger and Industrial Suoply. Use the data off the electric motor and in most cases it will cross over with newer part numbers.

 

[bulletsmith]

Blower fan went out in the wood burner. My model wood burner is discontinued from the maker so no OEM replacement. Secondary suppliers had knock-off models for $230ish. Reading the specification sticker, I typed that info in and found the current equivalent model from the fan maker - $58. It arrived yesterday and I hooked it up last night. I am at work now so I can not take/post pix. Here is the issue. Old unit was 2-speed HI-OFF-LOW, with a temp. sensor to turn it off and on, with an extension cord and plug. New model is 1-speed (listed as HI speed equivalent), no sensor and no cord/plug. I hooked up a cord/plug last night so wife had heat today. I can live w/o the 2-speed, we hardly ever used LOW speed anyways. Can I wire the old temp sensor into the new unit? When I took old one off, I opened it to get cord off to reuse. Temp. sensor was wired in to the WHITE wire. Is it just that easy? Rewire the new unit in-line with the white wire? I am no electrician. I can rewire anything where I am given and can see a diagram. But I know my limitations well enough to know its better to ask for help then to burn up a motor or the house. All help is welcome. Thanks.

If by white wire you are referring to the white conductor in the cord, then no. This would be an unsafe practice. As long as the cord is a standard cord with the white wire connected to the blade that's wider than the other, you don't want to switch it. Just wire your switch to the black wire (again, assuming this is a standard cord).

 

[17 squirrel]

If by white wire you are referring to the white conductor in the cord, then no. This would be an unsafe practice. As long as the cord is a standard cord with the white wire connected to the blade that's wider than the other, you don't want to switch it. Just wire your switch to the black wire (again, assuming this is a standard cord).

His original blower motor had two speeds, low and high. That's why the common was used for the thermostat on and off.
Don't change a thing OP.
Normal practice within the NEC.

 

[bulletsmith]

His original blower motor had two speeds, low and high. That's why the common was used for the thermostat on and off.
Don't change a thing OP.
Normal practice within the NEC.

You are stating that it is within normal practice within the NEC that the neutral is switched?

 

[17 squirrel]

You are stating that it is within normal practice within the NEC that the neutral is switched?

In those conditions ... Yes... This is not household and commercial wiring.
You have a two speed motor, that means in most cases two hot wires and a common plus a ground. You can't easily or at a reasonable cost break both hots to turn the motor on to run each speed.
You cut one wire , the neutral to cycle the blower motor on and off.
That's why there is no safe value of electricity. You use a meter and verify, always verify, and that's why they have prints and wiring diagrams.
I would be willing to bet that if you take a old ceiling fan apart you will find the same wiring with the fan motor. There's a three speed motor that one wall switch can turn off. They cut the netural to shut off the fan.
I also would tend to believe it has a UL Approved label attached to the blower assy.

 

[bulletsmith]

In those conditions ... Yes... This is not household and commercial wiring.
You have a two speed motor, that means in most cases two hot wires and a common plus a ground. You can't easily or at a reasonable cost break both hots to turn the motor on to run each speed.
You cut one wire , the neutral to cycle the blower motor on and off.
That's why there is no safe value of electricity. You use a meter and verify, always verify, and that's why they have prints and wiring diagrams.
I would be willing to bet that if you take a old ceiling fan apart you will find the same wiring with the fan motor. There's a three speed motor that one wall switch can turn off. They cut the natural to shut off the fan.

Here's the problem as I see it. The only instances I'm aware of that allow the grounded conductor to be switched, without simultaneously breaking all circuit conductors, is in the case of 3-wire motor control. In that case the only the overload contacts are allowed to exist in the grounded conductor side of the coil. You are talking about an appliance. The risk of switching the neutral is that a if the hot conductor comes into contact with the metal parts of the appliance , while the switch is off, it will not trip the over current protective device. A person touching the appliance, who has a good path to earth, completes the circuit.

What you are describing is electrically sound, it's just not safe.

 

[17 squirrel]

I didn't say I agreed with the practice. But its been done that way for decades and decades. It's a standard within manufacturing some products. And it's acceptable.
I also would believe they do it that way so they don't have to use a more expensive rotary switch and a capacitor.

 

[Cozy439]

Bulletsmith and 17 Squirrel - it appears you both know way more about this than I do. I will spend time tonight looking online for the diagram of the unit I have. I will also attempt to get pix when I get home tomorrow. Thanks and thanks for making each other clarify both sides of this.

 

[bulletsmith]

I can't debate that it is or isn't done. Sometimes we tend to accept practices as acceptable. I'm saying, with a degree of familiarity with the NEC, that I don't agree that it's acceptable to switch the neutral conductor. I'm also saying, with great certainty, that there is at least one scenario where harm can come to the users of such an installation.

Please don't take this as just me being argumentative, this stuff kills and it's important to be aware. Since the switch is yet to be installed, and one way of installing it is safer than another, why not error on the side of caution?

 

[bulletsmith]

Bulletsmith and 17 Squirrel - it appears you both know way more about this than I do. I will spend time tonight looking online for the diagram of the unit I have. I will also attempt to get pix when I get home tomorrow. Thanks and thanks for making each other clarify both sides of this.

No Problem. I have to make sure I don't **** him off, I still need info on my .17 project coming up

 

[churchmouse]

I have seen this practiced on a lot of HVAC equipment in the past. Older units that dropped the neutral to stop function. "But"........There were labels stating multiple power sources to make sure the mains were dropped for service.

 

[churchmouse]

No Problem. I have to make sure I don't **** him off, I still need info on my .17 project coming up

17 is a reasonable man...............Mostly.......

 

[Cozy439]

Pictures as promised
The unit as a whole...


Cover open, wires exposed...


Close up. 2 black wires out from fan. 1 black, 1 white, 1 green from cord.
Blacks were disconnected for clarity. The fan turns the correct way as is so correct black from fan is hooked to white from cord (right? Otherwise it spins in reverse...)

Cannot get picture of temp. sensor to upload, messages says file too large.

So... does this mean I need to wire the sensor between the two black lines or the white and black? All of what you two both say makes sense, nut exactly the reason I am here is to learn from the experts.

Thanks

 

[bulletsmith]

On that type of motor, polarity is not likely to make a difference with respect to rotation.

The white wire from the cord can stay where it is.

The black wire from the cord can be separated from the black wire from the motor. Your temperature switch should have two wires. Connect one of those wires to the black wire in the cord, and the other wire to the black wire to the motor.

When you are done, you should have three connections (I assume wire nuts):
1 - One will connect the white wire in the cord to one of the black wires in the motor.
2 - One will connect the black wire in the cord to one of the wires from your temperature switch.
3 - One will connect the remaining black wire in the motor to the remaining wire in the temperature switch.

 

[17 squirrel]

I am a very reasonable man,, And no feelings have been hurt here either. LOL.... Myself, I would leave the wiring as it was. But thats JMHO

 

[Cozy439]

I am a very reasonable man,, And no feelings have been hurt here either. LOL.... Myself, I would leave the wiring as it was. But thats JMHO

The reason for changing is the temp. sensor will turn the fan off when the fire dies down and not blow cold air. Is this a bad thing?.

PS: Again, thanks to you both.