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#22983 - 03/09/03 07:15 PM Wiring size for a long run  
ksan  Offline
Junior Member
Joined: Feb 2003
Posts: 3
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 07:51 PM Re: Wiring size for a long run  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
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

#22985 - 03/09/03 11:26 PM Re: Wiring size for a long run  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
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).]


#22986 - 03/09/03 11:34 PM Re: Wiring size for a long run  
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
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

#22987 - 03/09/03 11:54 PM Re: Wiring size for a long run  
Edward  Offline
Member
Joined: Dec 2002
Posts: 308
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

#22988 - 03/11/03 12:56 AM Re: Wiring size for a long run  
frenchelectrican  Offline
Member
Joined: Feb 2003
Posts: 939
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?)


#22989 - 03/11/03 07:38 PM Re: Wiring size for a long run  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
iwire — Sorry for the slow follow-up. Motor starting current is usually something like 6xFLC.



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