Motor wire size

I am installing a power source to my grinder, so I can remove several extension cords in my work area. Will # 14 wire handle my 1/2 hp grinder, and my radio. It's about 25 ft from the main. Thanks for your help. Stan

Personally, I'd go with #10 ROMEX .

Doc

yes

#14 will handle 15 amps. Size the breaker accordingly. Personally I would use #12 and a 20 amp breaker.

I"d go with #12.......#10 seems to me to be overkill!!
#14 would handle a 1/2 HP grinder (check the amps) but almost all outlets are #12 with 20 Amp breaker.
#14 is generally used on lighting circuits.

Heres an engineering approach and answer:

1) HAVE TO KNOW THE FLA TO GIVE AN ANSWER

HOWEVER I can make some educated guesses as follows:

2) ASSUMING That 1/2 HP Motor draws around 10 Full Load Amps if operated at 120 VAC Single Phase

3) The smallest wire I would specify would have to have a MINIMUM ampacity of 125% x 10 or say 13 amps. (Radio is very small draw I'm assuming, less then an amp Im guessing, but no warranty absent the radio specs)

4) 14 Gauge wire (in general, subject to enclosure and insulation and temperature) is rated for 15 amps

THEREFORE 14 gauge will suffice and meet code

HOWEVERRRRRRRRRRR If I were designing the circuit I would over engineer it a bit and allow room for expansion and even less voltage drop and even a biggggggg radio lol and go for a more useable standard typical 20 amp shop branch circuit

ALSO if the motor draws 10 amps you don't have much excess wiggle room to plug another load (in addition to radio) into the branch circuit if 13 to even 15 amps is all it can handle.

SO I WOULD USE 12 GAUGE WIRE (and that even reduces voltage drop some small extent)

Of course, heck you could go with 10 or 8 gauge wire and it can work but theres such a thing as too much overkill unless you plan to use a MUCH bigger motor in the future. Also, if youre gonna wire a typical box and a 15 or 20 amp receptacle (are you????) that wire is kind of BIG to fit and terminate!!!!

Use 12 Gauge is my advice but 14 suffices

John T

(quoted from post at 20:05:38 11/21/13) I am installing a power source to my grinder, so I can remove several extension cords in my work area. Will # 14 wire handle my 1/2 hp grinder, and my radio. It's about 25 ft from the main. Thanks for your help. Stan

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Check your building code. While #14 would work, where I live #14 wire is only allowed for switch legs on lighting circuits. Even if your code allows #14 I suggest using #12 so you can use the circuit for other things.

I checked my grinder is draws 5.8 amps. I am tapping into a receptacle that is 12 ga from the panel on a 15 amp breaker. If I were going to buy new wire I would go with 12 ga, but since I already have 14 ga looks like from what I am reading I can get by with 14ga. Stan

If you are tapping on to a 12 gage circuit........ You NEED to use 12 to be protected. Even if you are on a 15 amp breaker now, someone might notice the #12 on 14 bkr and upgrade to 20 amp. What is a few bucks? joe

I learned years ago it code calls for #14 I use #12 just so I know the wire is over kill and that way if in the future I need heavier wire to run something it is already there. Back some 25 or so years ago when I wired my dads shop I use #12 in most places and #10 or better for any 220 stuff

You will be happier with a double pole 20 amp breaker. 12/3 wire and a 20amp T-slot receptacle.

Stan, you already said that its a 15 amp breaker. 14 guage will work just fine for that 15 amp breaker. Sure, you could do as others say and run 12 guage (20 amp). Heck, you could run 10 guage (30 amp), but your circuit breaker is 15 amp. The important thing is that your wire and receptical are rated at equal to or greater than your circuit breaker, NEVER less than. You are equal to, and thats what you have in stock, use it. You are drawing less than 15 amps, far less than, so do it.

Heck, you could run 8 or even 6 guage might fit in the lug, but your breaker is only 15 amp. You are ok.

Good luck.

Mark

Just remember stan, you'll be putting a load on that grinder when you use it.

Thanks for the feedback, okay based on the new information heres the engineering:

1) 14 Gauge wire (15 amps) will suffice just fine as the expected continuous load is less then 12 amps......

2) 14 Gauge wire requires a 15 amp overcurrent protection device AND YOU SAY THATS WHAT YOU HAVE so that"s okay.

Do things right and you will be safe, beware of Billy Bob and Bubba Im always warning people about lol

John T

WHY

Never could figure out how they rated #14 at 15 amps when it overheats the wire bad with that draw. It's a dangerous wire that shoulden't even be made for inside wiring. JMO

There is no reason to run a 15 amp circuit in a shop for anything but lighting. Sooner or later you're going to plug something into that outlet that will trip the breaker.

I watched a film once where it took 90 amps for 14/2 wire to start to smoke.If it was dangerous it would not be used to wire every room in the house except kitchen and dining room.Only reason dining room is for large coffee pots at parties.

Bad practice to mix two wire sizes in the same rsidential circuit.

Zacalacaly . The electrician will think he is doing you a favor by replacing that 15 for a 20 for the 12 awg wire size not knowing it splices to 14 later in the circuit.