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#59696 - 12/12/05 07:03 PM suggested wire size
jkraft Offline

Registered: 05/05/03
Posts: 75
I'm installing a 1.5 hp 230V 11 amp single phase fan motor from a 120/208V panel about 250 feet away. Any suggestions for wire size.

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#59697 - 12/12/05 07:37 PM Re: suggested wire size
bot540 Offline

Registered: 09/14/04
Posts: 177
Loc: Vernon Hills, IL
Jesus may have been a capenter,but God was an electrician.Genesis1:3

#59698 - 12/12/05 08:08 PM Re: suggested wire size
George Offline

Registered: 02/23/02
Posts: 380
maybe only #10.

#59699 - 12/12/05 08:31 PM Re: suggested wire size
Bob Offline

Registered: 02/05/02
Posts: 182
Loc: Mobile, AL, USA
Have you tried to do the VD caculations yourself?

#59700 - 12/12/05 09:50 PM Re: suggested wire size
gfretwell Offline


Registered: 07/20/04
Posts: 9025
Loc: Estero,Fl,usa
10 drops 6.6v, 12 drops 10.6v @ 11a
Greg Fretwell

#59701 - 12/13/05 02:53 AM Re: suggested wire size
jkraft Offline

Registered: 05/05/03
Posts: 75

I apologize, I have not. I was hoping someone would have previous experience with this.


#59702 - 12/13/05 04:02 AM Re: suggested wire size
resqcapt19 Offline

Registered: 11/10/00
Posts: 2209
Loc: IL
Not all 230 volt rated motors are suitable for use on 208 volt systems. The voltage drop will make this problem worse.

[This message has been edited by resqcapt19 (edited 12-13-2005).]

#59703 - 12/13/05 06:17 PM Re: suggested wire size
renosteinke Offline
Cat Servant

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
Don is quite right; even under the best of conditions, you're really pushing it when you try to run a "230v" motor on 208 volts.

As a general rule of thumb, a motor may be used at plus or minus 10% of the nameplate marked voltage. So if your nameplate avtually reads simply "230v", then it should have a minimum of 207 volts at all times- and make sure that value is measured "under load!"

Now, if the motor is marked 220, or 208/230, etc...well, you get the picture.

I would also be very conservative in allowing for voltage drop. Remember, motors- especially those used in compressors- have a considerably higher curent required for starting; you almost want to base your voltage-drop calculations on the "LRA", or 'locked rotor amps.'

An exhaust fan isn't really fighting a load as it is starting up; so the inrush current needed isn't as great as it might be in other applications. You will probably be able to use #8.

One thing to also consider is a motor satrter with electronic overloads ("heaters"). Even though strictly not necessary, it will provide additional protection for the motor. The electronic elements provide protection against many other power problems than simple 'heaters' do.


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