newbie furnance motor-blower wiring question

[dbest888@hotmail.com]

I have an old motor-blower assembly from a furnace that i am thinking
of using for an air filtration system. I would like to hook it to a
on/off switch, then to a plug so i can plug it into a receptable.

motor ===== on/off switch ===== plug ->receptable

From the motor assembly, i
see only a two uncolored wires. How do i wire this so that i willbe safe?
Can i just wire it without ground to the switch thten to the two prong plug?
Thanks in advance,

 

[Phasor]

Can i just wire it without ground to the switch thten to the two prong plug?

There's two answers to that - it depends how safe or unsafe you want to be... :shock:

Use a 3-core cord and 3-prong plug (with the earth connected all the way through, of course), and terminate the earth wire somewhere on the motor's chassis (you'll probably need a lug on the end of the earth wire).

The switch must operate in the ACTIVE (hot) lead, not the neutral - unless the switch is a double pole switch, with switches both active AND neutral.

 

[Agent 009]

Don't you think that polarity would affect the motor's direction of rotation?

 

[Phasor]

Don't you think that polarity would affect the motor's direction of rotation?

For a single phase AC motor, no, polarity does not affect it. Even for non-permanent magnet DC motors, polarity reversal will not affect the DOR.

In order to reverse the direction of a single phase motor, it is necessary to reverse EITHER the starting winding, OR the running winding, but not both.

 

[Agent 009]

Yes, indeed, AC motors aren't affected, or if they were, the vaccum cleaner would start throwing out the dirt, if just you switched the orientation of the plug... But for DC motors, I didn't know that they could not be affected by the input's sign...

 

[Phasor]

But for DC motors, I didn't know that they could not be affected by the input's sign...

Reversal of a DC motor is, in a way, similar to reversal of the AC motor - either the rotor winding, or the stator winding must be reversed, but if you reverse both windings, the rotation remains the same.

 

[stevez]

Regarding the switch - make sure the contacts are rated for the application. Usually in the US the switch will have a current rating in amperes as well as a HP (horsepower) rating to address the inductive properties of a motor load. A switch that doesn't have a HP rating probalby shouldn't be used.

 

[dbest888@hotmail.com]

one more question

Thanks guys!! This is the first time i posted here...can't believe the quick reponses. Much appreciated guys!!

I just have one followup question. Since i will be using this in a air filtration system, how must is dust a concern since the the motor is not an enclosed one. Would it be sufficient just to put the motor=blower in an enclosed area, with a filter on the intake??

 

[jeff1608]

I have done air cleaners in the past. The (blower) motors I used had 3 speeds (high,med.,low). I enclosed them in a box that had 2 openings. Where the air went in I put a electrostatic furnace filter on and where the air came out I put a grill on. It seemed to work great until one day I notice a lot of dust coming out. I picked up a handful of saw dust and drop it by the filter. That's when I noticed that it would catch the larger particles put not the fine dust (the ones that plug your lungs). So unless you can find a really super good filter, it won't work well.

I find furnace (blower) motors are great fans. The bigger ones can blow air up to 40-50 feet. Great to have around when you're working outside on a hot summer day.