Electrical Question - Almost Done with the Shop....

[Justin Jump]

Hello all....

Joined a few months ago, nad have been reading as much as I could. I got an electrical question, maybe more like advice......My uncle, who works in construction, was able to score me a 250' roll of 10/3 for wiring.

I am concerned that some of the equipment, existing and future, may require 8/3, but my initial research of most table saws, routers, etc, seem that I should be OK with 10/3.

Even the heat pump I plan to put in next year, a wall mount Mitsubishi unti, calls out 30 amp max, wich seems that 10/3 should be OK.

Any advice on the wiring, should I run some 8/3 circuits?

Thx,

JJ in Pittsburgh - Outside of Shop Picture Attached.....

[Sean Kinn]

I have to ask...what machines are you thinking of that will require 8-3? I'm using 12-2 w/ground for all curcuits up to 20A, and 10-2 w/ground for the largest machine that calls for a 19.6A circuit. Other than exceptionally long runs, or some truly commercial-sized machine, welder, etc. I can't think of any "common" tools that would require the 8-3. Since you got it for a good price I would just use up the 10-3, and consider heavier later only if needed.

[Justin Jump]

My plan is the norm, table saw, dust collection, planer, jointer, setup....air compressor in the basement, nothing in the plans I can research are over 20 amps or so....

Just one piece, my TIG welder, needs 6/3, but thats already ran (had to pay for this one though!!)

[Kirk Poore]

I have 10 ga wire on my 240V circuits, with 30 amp breakers. This is sufficient for 5 hp single phase motors. It would be quite unusual for you to need more than that in a shop. If so, you could put in a dedicated line later. But 8 ga is a lot more expensive, and I doubt it will give you anything you really need.

Kirk

[Duane Bledsoe]

Hope this helps....the following wire gauge sizes have the current carrying capacity listed. Each one's current capacity is also the size breaker you should use, and should not exceed, while using each one. Also, if you were to upsize the wire, the breaker may need to be upsized with it due to the fact that a lot of them are made to only accept the size wire they are intended for. NEVER under any circumstance should you use a larger sized breaker with a smaller sized wire (example, 30 amp breaker with 12 gauge/20 amp wire). Current builds heat, and the larger breaker will allow the rated current to pass through it, but a smaller wire cannot carry it safely and may overheat. This causes fires.

14 AWG wire = 15 amp capacity
12 AWG wire = 20 amp capacity
10 AWG wire = 30 amp capacity
8 AWG wire = 40 amp capacity
6 AWG wire = 50 amp capacity

[Daniel Berlin]

Hope this helps....the following wire gauge sizes have the current carrying capacity listed. Each one's current capacity is also the size breaker you should use, and should not exceed, while using each one. Also, if you were to upsize the wire, the breaker may need to be upsized with it due to the fact that a lot of them are made to only accept the size wire they are intended for. NEVER under any circumstance should you use a larger sized breaker with a smaller sized wire (example, 30 amp breaker with 12 gauge/20 amp wire). Current builds heat, and the larger breaker will allow the rated current to pass through it, but a smaller wire cannot carry it safely and may overheat. This causes fires.

14 AWG wire = 15 amp capacity
12 AWG wire = 20 amp capacity
10 AWG wire = 30 amp capacity
8 AWG wire = 40 amp capacity
6 AWG wire = 50 amp capacity

Just to point out: the 6 AWG capacity is wrong, it should be 55 (even for NM-B which uses the 60C rating).
At least, that is what 2008 and 2011 NEC says.
Additionally, if you are running them all as individual wires in properly rated conduit, the capacities of 8 AWG and 6 AWG would be 50 and 65 respectively (75C rating, since i'm not not aware of any consumer level 90C rated breakers).

The rest is good advice. Never mess around with electricity. If it doesn't electrocute you it'll burn you.

[Van Huskey]

It would be unusual to run into a single phase piece of woodworking equipment needing more than a 30 amp 240v circuit, in fact the vast majority of "hobby" woodworking machines are not going to need more than 20 amp 240v. The exceptions to this is if you plan to get one of the larger Italian bandsaws 20+ inches some off them require a 40 amp circuit, the other exception is if you plan to look for used industrial equipment, even though they will probably be 3 phase they will likely need some more ampacity no matter how you end up running them.

[Kirk Poore]

... the other exception is if you plan to look for used industrial equipment, even though they will probably be 3 phase they will likely need some more ampacity no matter how you end up running them.

Actually, 3 phase motors require smaller wires for the same horsepower. For example, my 1ph 5 hp DC motor takes 19 amps, and will be on a 30 amp/240v/1ph circuit (10 ga wire). My 5 hp 3ph bandsaw motor only takes 13 amps, and starts fine on a 20 amp/240v/3ph circuit (12 ga wire). However, since industrial motors can quickly get much bigger than 5 hp, you are correct in implying that the bigger motors need bigger wires.

Kirk

[Justin Jump]

So - the bottom line is 10/2 is good enough for almost all my tools - the fact that my 10/3 was free, just use it and not use the 3rd conductor.....

Thanks for all the fast responses.

JJ in Pittsburgh

[Daniel Berlin]

So - the bottom line is 10/2 is good enough for almost all my tools - the fact that my 10/3 was free, just use it and not use the 3rd conductor.....

Thanks for all the fast responses.

JJ in Pittsburgh

If you have 10/3, wire the circuit with the black (hot), red (hot), and ground (ground), and cap off the white.

That will make it blindingly obvious to anyone that both legs are hot.

[Van Huskey]

Actually, 3 phase motors require smaller wires for the same horsepower. For example, my 1ph 5 hp DC motor takes 19 amps, and will be on a 30 amp/240v/1ph circuit (10 ga wire). My 5 hp 3ph bandsaw motor only takes 13 amps, and starts fine on a 20 amp/240v/3ph circuit (12 ga wire). However, since industrial motors can quickly get much bigger than 5 hp, you are correct in implying that the bigger motors need bigger wires.

Kirk

Agreed, I was going on the assumption he would never have 3 phase power to the socket, he would either run an RPC, VFD or remotor all of which will likely tax a 30 amp 240V single phase circuit even at 5hp.

[Ken Harris]

This is what I did with circuit for table saw.My motor is 3 horse If I remember it pulls 16 or 17 amps,so I used 12/3.At the table saw I have a router table on far right side of the cabinet saw,I installed a 2 gang plug near on/off switch and another 2 gang 20 amp plug just before 120 circuit goes to power switch for the router.Since you already have a neutral why not utilize at your machinery and install plugs.In your case since the wire is #10 you would have to have a 20 fuse ahead of any plugs.Just another thought to throw in the mix