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#22983 - 03/09/03 03:15 PM Wiring size for a long run
ksan Offline
Junior Member

Registered: 02/23/03
Posts: 3
Loc: Gulf Breeze, Florida
I need to run 115 to a motor rated at 10.6 amps that is about 250 ft from the main service. The motor is the only thing on the circuit. Is 12 guage wire sufficient or should a smaller guage be used?

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#22984 - 03/09/03 03:51 PM Re: Wiring size for a long run
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
Using a voltage drop calculator I got on the Web and the info you gave you will have voltage drop of 10.5 volts or 9.2% if you use #12

#10s would be 5.5% drop or 6.3 volts
#8s would be 3.5% drop or 4.0 volts
#6s would be 2.2% drop or 2.2 volts
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#22985 - 03/09/03 07:26 PM Re: Wiring size for a long run
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
Not wanting to throw a wrench in the gears, remember that for motors, one needs to also consider starting voltage drop. A rule of thumb for starting is 15% maximum. This is why 230 and 460V motors become attractive.

{Note that starting voltage drop is not a Code requirement, or even an FPN. Overlooking it can cause problems, and is commonly part of the commercial and industrial design process.}




[This message has been edited by Bjarney (edited 03-09-2003).]

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#22986 - 03/09/03 07:34 PM Re: Wiring size for a long run
iwire Offline
Moderator

Registered: 01/05/03
Posts: 4343
Loc: North Attleboro, MA USA
Bjarney, not a wrench in the gears but do you apply the 15% to the FLC, so 10.6 x 1.15 = 12.19 amps and then apply the voltage drop calcs. And does 15% work for all voltages.

Bob
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts

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#22987 - 03/09/03 07:54 PM Re: Wiring size for a long run
Edward Offline
Member

Registered: 12/14/02
Posts: 309
Loc: California
Check to see if you can wire it to 240 Volt
If you can then use 240 Volt connections and use 8 AWG wires.

Edward
_________________________
Thanks
Edward

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#22988 - 03/10/03 08:56 PM Re: Wiring size for a long run
frenchelectrican Offline

Member

Registered: 02/06/03
Posts: 938
Loc: Wi/ Paris France { France for ...
ok i look at my electican calculator and for 115 volts appactions for that kind of distance i recomoned #10 is minumin wire size other wise if the moter can change to 230 volts. if so all by the mean go for 230 volts and i got one note from power company say any electric moter over 1 1/2 hp will like to keep on high side (voltage) due less stress at the transformer and line effcts and btw most motors dont like to start when voltage get too low ( i have alot of sevrvice call with waterwell pumps and came with way too small a wire size )


merci marc
_________________________
Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)


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#22989 - 03/11/03 03:38 PM Re: Wiring size for a long run
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
iwire — Sorry for the slow follow-up. Motor starting current is usually something like 6xFLC.

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