Not satisfied with SawStop's answer?

[Steve Mathews]

I just finished assembling a recent SawStop purchase, an ICS with a 5hp single phase motor. I was prepared to install 10/3 SOOW cable to the saw but the supplied strain relief on the SawStop terminal box is too small and the opening on the terminal box is sized for 1/2" conduit. SawStop technical support stated that 12/3 wire is OK. I looked inside the cabinet today and found all of the strain relief fittings to the motor and contactor box are the larger size for 3/4" conduit. I still think 10/3 cable is more appropriate for a 5hp motor and the strain relief fittings should be larger. Comments?

[Paul F Franklin]

10/3 would be preferable, assuming this is for 240 volts. If it's a short run, 12/3 would be ok. Ampacity for typical SO or similar cable is higher when only two conductors are current carrying (as they would be for a 240 motor). Typically 25 amps instead of 20 amps with 3 current carrying conductors. That's going to be close for a 5 HP motor running at full load, but as a practical matter, you probably won't often run at full load for long periods of time.

A step drill makes quick work of enlarging the knockout if you don't have or can't borrow a greenlee punch.

[Dan Friedrichs]

It's a short length, so voltage drop is not much of a concern (unlike, say, a long run to a panel). And it's exposed - not hidden in a wall - so its ability to dissipate heat is much better. So you can get away with smaller gauge than you'd use for a service conductor.

Just looking at a random SO cable vendor's ampacity table, I see a 12/3 cable rated for 25A in single-phase service. That's good for ~8HP.

Use the 12/3.

[johnny means]

I'm betting the SawStop engineers know what they're doing.

[scott vroom]

NEC 2017 Table 400.5(A) (1) states that 12ga SOOW cord is approved for 25 amps in a 2 conductor application.

[Ben Rivel]

Ha, dont worry Steve, SawStop kinda knows what they're doin...

[Frank Pratt]

I wanted a longer cord for mine (3HP), so I just cut the cord to about a foot long & put a twist lock plug on it. I then made a longer extension cord using 12/3 & twist lock connectors. It is so cramped in the control box that I didn't want to mess with it and not take a chance on messing up the warranty.

But ya, like the others said, what SawStop built it with will work fine.

[Patrick Irish]

My used cb (ICS) came with 10/3 hooked up. I checked all connections and they seem to fit on mine.

[Bill Dufour]

Ask them why they wasted money on 3/4" fittings if they do not need the larger cable.
Bill D.

[Mike Cutler]

Steve

You're not limited to just SOOW/SJOOW cord. 3/C 10awg comes in other outer jacket materials. PVC, TFE, etc.
Go to your local home center and measure the diameter of the 3/C #10 and then go over to the extension cords and find a #10 cord with a PVC jacket and measure that. It will probably fit through that 3/4" conduit connector.

[Carl Beckett]

but as a practical matter, you probably won't often run at full load for long periods of time.



This is my thinking. If I am pulling full current for continuous time frames on a 5hp table saw I would worry my setup is dangerous... (you production guys can set me straight, but as a hobbiest I havent come close to pushing the limits of the 3hp saw even - sharp blades and proper technique goes a long ways)

Code already has a certain safety margin built into it, so doesnt seem necessary to add another layer of margin on top of that.

What rating is the socket you are plugging it into? (I assume 30A outlet?) I am not an electrician, and on 'most' of my equipment the wall wiring (sized for 30A wiring/sockets/breakers) feed a piece of equipment that has a cable and internally wiring rated for much less. Short distances so its not a Vdrop concern. Then a motor has internal protection and may be treated a little differently as a load than say pure resistive loads.

[eugene thomas]

I would put 10 gage wire on so I can use 30 amp breaker. If go with 12 gage wire would need 20 amp breaker. Seen one site that listed amp draw of 20.8...

[John Lanciani]

I would put 10 gage wire on so I can use 30 amp breaker. If go with 12 gage wire would need 20 amp breaker. Seen one site that listed amp draw of 20.8...

This is false logic. Aside from the fact that The NEC does not cover cord and plug installations if this logic held true every single table lamp in America would be unsafe since they are all wired with 16 or 18ga cords and plugged into 15 and 20 amp circuits. As posted above, #12 S cord is listed for 25 amps continuous, there is no need for anything larger. A table saw in a hobby or one man shop is intermittent duty at best, it’s not like a heater that may run continuously at full load for hours on end.

[Marc Jeske]

Many 10/2 + gnd portable cables will just BARELY fit through a 1/2" romex connector.

Bring the connector to the store and see if the cable fits it... I used drop of dishsoap last time, was snug, but worked out for air compressor 30 a ckt.

I would have used a step bit to enlarge to 3/4" KO, but the Condor pressure switch housing wasn't overall agreeable dimensions to accept the bit.

Marc

[eugene thomas]

Ya know John. I really don't care what is the NEC. I care about what makes sense to me. So in my shop if tool takes more than say 20 amps gets cord with breaker rated for more. But you seem to be the expert.

[Simon MacGowen]

"SawStop technical support stated that 12/3 wire is OK."

These guys err on the safe side, and so 12/3 is fine for any hobbyists if they say so. Have you ever run your saw, any saw, non stop for half an hour at a time? I doubt anyone including those who do woodworking for a living in a non-industrial setup would run any of their machines (saws, routers, etc). non-stop for hours at a time.

Simon

[David Kumm]

As good as that company is with ergonomics and user friendly features, a larger box and knockouts seems like a no brainer. Not much cost and it sure makes life easier when you can use either size wire or connectors. I generally use 10 soow and 30 amp twist lock to have some uniformity around the shop and it is a pain to have to buy smaller wire or work in a small box. Dave

[Mike Cutler]

Steve

10/3 SO cord has an outer diameter of .670.
12/3 SO cord has an outer diameter of .610.
10/3 PVC has an outer diameter of .550.
12/3 PVC has an outer diameter of .490

10/3, or 12/3 is your decision. Ampacity for 10awg is 30 amps. 12awg is 25 amps.
FLA for a 5HP motor is 28 amps.
10/3, or 12/3 SO cord, is limited to the amps spec'd if the cord is less than 50'.

[Dan Friedrichs]

Those of you who favor 10/3 might want to think about your logic, for a second.

All wire gets hot when current flows through it. Picking wire size is just a question of "how hot is too hot?".

To be SUPER SUPER conservative, it was decided that 10AWG was sufficient to carry a continuous 30A load, even when that wire runs through a hot, insulated attic in the middle of summer in Arizona. Even in that adverse situation, 10AWG is the right size to not get too hot.

Now: why does anyone think 10AWG is required in an intermittent duty application, in a shop (probably laying on a cold cement floor)?

[Mike Cutler]

Dan

No arguments from me.
I'm in agreement with John Lanciani. #12awg would be fine for this application. If memory serves, John is also a licensed electrician, so I'm confident in his answers. The awg of the wire coming out of the plug, has little to do with the size of the wire required to feed the receptacle.
The OP however wants a solution to use #10. It's his house, and his shop, and #10 certainly wouldn't be the wrong choice. I am only trying to provide an answer to the solution he wants to use, not change his mind.
Both cables have the same curves for heat. It's length that makes the difference.
Both of the 5HP motors I have are on #10, simply because they are both on SOOW "extension cords" that are right at the 50' length. I could have used #12, but one is an air compressor, the other is commercial washing machine. The washing machine probably has an actual 5hp motor, the air compressor is probably about 4-4 1/4, not counting service factors, and the manufacturer just used a little "Madison Avenue Engineering" to make it a 5HP. Probably the same "engineering " used for most new "5HP" wood working machines. Additionally, my "extension cords" have been known to spend the winter outside powering up trough heaters, for horses, from time to time. ;)

All of this info is readily available on the Southwire website for anyone to access. You don't need to be an engineer, nor a licensed electrician, to understand it. Engineers Toolbox is another valuable website resource, for all kinds of topics.

[Dan Friedrichs]

Absolutely, Mike - and I think your idea of PVC cord is pretty slick, if one wanted to squeeze 10awg in that spot.

[Steve Mathews]

Before purchasing the ICS I contacted SawStop and they recommended a dedicated 30A circuit, which I did using 10 gauge wiring and a twist lock receptacle. Looking more closely at the internals of the saw, the cable between the contactor, main switch, motor and terminal box is SOOW 12/3. It originally looked like 10 gauge because of the thicker 600V outer covering. So in conclusion, it looks like the 12/3 SJOOW (20' in length) I'm using based on SawStops recommendation is OK. The 5hp motor data plate shows 19.7A. 19.7A x 1.25 = 24.625A The 12/3 SJOOW is rated for 25A. Is this what makes it OK?

In response to one of the earlier comments. The SawStop Industrial cabinet saws do not come with a power cord like their Professional models.

[Mike Cutler]

Steve

What makes it okay is the length of the cord, that it is only 2 current carrying conductors, and that it highly doubtful you will exceed the temp rating of the cable/conductor.
If you were to need to run a very long extension cord, say 100', than you would have to go up a size. To account for the voltage drop, and ampacity loss, of a longer cable.
I know that you ran #10 aww to the 30 amp receptacle, per the NEC, but it's as John Lanciani pointed out,the gauge of wire for the device plugged into a wall receptacle may have very little to do with the gauge of wire going to the receptacle.

I personally think it's kind of crappy that machines do not come with power cords. I understand why they do not, because the manufacturer can't possibly forecast all of the different installations, but they should at least be outfitted with the minimum length, and gauge, cord so that if a person were to change it, they would know it had to be "upsized".
I feel it leaves the owner in a vulnerable position. Simply stating to have the power connected by a licensed electrician can open a person up to some very expensive wiring mods, if they don't know any better. To make your cord will probably cost $50-$60 dollars. To hardwire it per the NEC might easily cost you twenty times that amount. Both installations are correct, and neither is wrong.

12/3 SOOW is still a fairly good sized cable, diameter wise. I would make sure it will fit through the strain relief first.

[Martin Wasner]

As good as that company is with ergonomics and user friendly features, a larger box and knockouts seems like a no brainer. Not much cost and it sure makes life easier when you can use either size wire or connectors. I generally use 10 soow and 30 amp twist lock to have some uniformity around the shop and it is a pain to have to buy smaller wire or work in a small box. Dave

The knock outs are never the ideal size unless it's on 480v. Then it's a hotdog in a hallway.

It's not the saw manufactures fault either. They don't make the control housings.

Some of the euro stuff is down right infuriating trying to shove wires into the cabinet. Or, they put them in a really stupid spot and it's a bear to put a strain relief on.