14-3 SJ Cord

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Old 10-15-04, 10:00 AM
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14-3 SJ Cord

I need to replace the cord on my 14 amp, 115 volt table saw. I plan on getting 14-3 (2 conductor + 1 ground) SJ. Would this type of cord also work with a 12 amp, 230 volt table saw?
 
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Old 10-15-04, 10:10 AM
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Why do you ask?
 
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Old 10-15-04, 10:59 AM
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I'm remodelling the shop and need a longer cord for the TS. I plan on purchasing a new 12/230 saw in the next year or so and hope I only have to purchase one 17-foot long cord. A rubber cord protector will be used for the run along the floor.
 
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Old 10-15-04, 11:01 AM
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What size circuit breaker protects the receptacle circuit you will be plugging into?
You have cross the line from a manufacturer supplied cord, and an owner supplied. Now that you are buying it, you should follow the NEC. If the receptacle circuit will be a 20A breaker, then you need 12/2 (two insulated conductors and one ground). The insulated conductors can be line and neutral (for 120V equipment) or line and line (for 240V equipment).
 
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Old 10-15-04, 11:44 AM
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Thank you for pointing that out. The existing breaker is 20 amp and the breaker for the new saw will be 20amp 2-pole. I was going off the amp rating for the motors (12 and 14) which is wrong. I'll get 12-3 instead.
 
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Old 10-15-04, 04:20 PM
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Flexible cords are sized acording to the appliance, not the circuit. If the opposite were true, a table lamp plugged into a DR receptacle would require a 12ga cord.

A 20 amp circuit requires a minimum of 18ga cord. You are fine with 14/3 SJ. 14/3 SJ has an ampacity of 18 amps since it has only two current carrying conductors. Cords do not follow 240.4(D).
 
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Old 10-15-04, 05:04 PM
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Petey,
Could you update that code reference. It doesn't pan out to backup your point.
I figure manufacturers can decrease conductor size as a sample of the total product gets tested by a third party (UL).
 
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Old 10-15-04, 05:15 PM
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Ok I've been successfully confused again. LOL

I see the 18 amp reference in my electricity book from 1986. But from a logical standpoint, how is this safe? If the motor were to overdraw wouldn't the cord become unsafe?

FWIW, the manual for the 12amp/230volt saw I am looking at recomends a 20 amp breaker. My current 14amp/115volt saw runs on a shared 15 amp circuit. The lights dim everytime it goes on. It will go on a dedicated 20 amp breaker when the remodelling is complete.
 
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Old 10-15-04, 05:43 PM
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400.5, 400.6, Table 400.5(A) column B+
Most importantly; 240.5, then 240.5(B), then 240.5(B)(1)

The 18ga is a minimum. The cord needs to be sized according to the appliance draw.
 
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Old 10-15-04, 05:47 PM
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Flexible cords are under article 400, which includes a separate table of ampacities for conductors. Flexible cords are rated with different assumptions for heat dissipation (here is a hint: if you ever use a flex cord at the maximum current in table 400.5(A), _don't coil it up when in use!)

Thus it would be entirely acceptable to use 14ga cord on a 20A circuit for a 13 amp load.

However this may not be the best installation. Remember that motor draw large inrush currents when starting. This won't cause appreciable heating in the 14ga cord, but the resistance of the 14ga cord might result in poorer starting of the motor. Not knowing the details such as length of circuit from panel to receptacle, length of cord from receptacle to saw, and starting amps of the saw, I cannot make specific recommendations, but you may want to use anything from 12ga for the in wall wiring and 14ga for the SJO cord, to 10ga for everything.

Lastly, was this saw specifically sold with a plug in cord, or was it made for hard wiring? If made for a plug in cord, then the manufacturer has determined that it is safe to use with ordinary receptacles. But in general, motors require special 'horsepower' rated receptacles.

-Jon
 
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Old 10-16-04, 07:14 AM
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Art 240.5, Protection of Flexible Cords----, (1) Supply-cords----- "Where a flexible-cord-- is-- used-- it shall be permitted to be supplied by a Branch-Circuit ( as follows)---

"20- amp B-C ---- #18 cord & larger"
"30-amp B-C------ #16 cord & larger"

"40/50 amp B-C---- cord with 20-amp rating and over"
 
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Old 10-16-04, 08:21 AM
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winnie

Thanks for the information. Both saws are designed to be plugged in. I think I will still go with the 12-3 to be safe. I'm learning so much from you guys...thanks again.
 
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