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Sizing new power cord for Grizzly jointer

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Forum topic by moosie posted 05-09-2019 04:57 PM 884 views 0 times favorited 34 replies Add to Favorites Watch
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moosie

14 posts in 767 days


05-09-2019 04:57 PM

Hi,

I just received a Grizzly 0858 jointer. The power cord is about ten feet, and I want to replace it with a 20-25 footer. The unit is rated 12A @ 240V, and comes with a 14 gauge cord. I suspect I can get by with 14 gauge, but to be safe I plan to use 12-3.

I’m considering just getting a standard 120V cord and chopping the ends off. Wire direct into the machine, and fit a male 6-20 on the other end.

Is there any reason I shouldn’t do that? All the regular 12-3 extension cords say rated for 125V on them, but is that relevant in this context?

Thanks.

By the way, real quick unboxing review of the jointer:

This unit comes all assembled, in a plywood crate. All I had to do was mount the control panel pole, which was folded down for transport. The hardest task was getting it off the pallet.

The preservative gunk on the cast iron came right off with a bit of naphtha on a shop towel. Then it got a light coating of Boeshield T-9.

Quality control was excellent on this beast. Table flatness and coplanarity are all within .001” overall.


34 replies so far

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moosie

14 posts in 767 days


#1 posted 05-09-2019 05:03 PM

Follow up info:

I calculate wattage through my power cord to be 12A x 240V = 2880.

I’m looking at a typical 12-3 extension cord, and it says max is 125V @ 15A = 1875 watts.

https://www.homedepot.com/p/Duromax-XPC12025A-25-ft-12-3-Gauge-Single-Tap-Extension-Power-Cord-XPC12025A/302795695

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bigblockyeti

5782 posts in 2141 days


#2 posted 05-09-2019 05:43 PM

12-3 should be perfectly fine for what you’re trying to do. If you look at the jacket on the cord, It’ll likely say 250V or 600V max.

-- "Lack of effort will result in failure with amazing predictability" - Me

View CarlosInTheSticks's profile

CarlosInTheSticks

395 posts in 793 days


#3 posted 05-09-2019 05:44 PM

If your going to a 25 ft. cord then definitely go with a 12-3 cord. The 125V at 15A designation is for a 125V circuit which has 1 hot and 1 neutral wire. For a 240V circuit you would have 2 hot wires which means your actually good for double the wattage 2(125V at 15A) = 3750 watts.

-- "There are no utopias, chaos theory reigns, anyone who says different is selling you something"

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Smirak

99 posts in 939 days


#4 posted 05-09-2019 05:55 PM

When I extended the power cord for my G0833P table saw, I went with 12-3…

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BlueRidgeDog

497 posts in 200 days


#5 posted 05-09-2019 06:00 PM

I always go up a size for stranded and make my cords out of #10, but 12/3 would easily handle it. 12 house wire would be code for 20a, 14 is approved for 15a.

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clagwell

29 posts in 213 days


#6 posted 05-09-2019 06:19 PM

The current and voltage ratings are for the extension cord in total, not the cable. The extension cord ratings are, in this case, determined by the connectors. The connectors are 5-15. That makes it a 125V 15A extension cord. The cable itself will be good for at least 300V 25A (cords have a higher current rating than Romex).

Btw, 12awg is overkill here, a 14awg cord is rated at 18A, and 25’ will only drop about 1.5V at 12A. Your motor is likely rated for 230V operation which allows for 10V drop from a 240V supply.

Check the gland where the power cord enters the unit. Make sure it will take the larger cable if you choose that route.

-- Dave, Tippecanoe County, IN

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SMP

1190 posts in 326 days


#7 posted 05-09-2019 06:39 PM

sometimes extension cords can be limited by the ratings of the plug(the least common denominator). I’ve had cheap extension cords where you plug something in and you see sparks and the arc literally fries the connectors.

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CarlosInTheSticks

395 posts in 793 days


#8 posted 05-09-2019 06:55 PM

For long cords the issue is not so much current draw as long as it is below rated draw, but the heat build up in a long cord, the longer the cord the more resistance and the more heat generated in a 240V circuit with two hots double the heat generation. You can get away with it in a 6’ cord, on a long extension cord it is always recommended you go a size larger, you will usually find this warning in the literature.

-- "There are no utopias, chaos theory reigns, anyone who says different is selling you something"

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CarlosInTheSticks

395 posts in 793 days


#9 posted 05-09-2019 07:01 PM

SMP sounds like you tried to plug a 115V plug into a 240V or something like that. Your plug connectors are marked with there ratings and should match the circuits they are connected to.

-- "There are no utopias, chaos theory reigns, anyone who says different is selling you something"

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clagwell

29 posts in 213 days


#10 posted 05-09-2019 07:29 PM


...more heat generated in a 240V circuit with two hots double the heat generation…

Both 120V circuits and 240V circuits carry current on two wires. The current in the 240V circuit is half that of the 120V circuit. So if the same wire gauge is used the heat generated in the 240V wiring is one fourth that of the 120V circuit.

For long cords the issue is not so much current draw as long as it is below rated draw, but the heat build up in a long cord, the longer the cord the more resistance and the more heat generated..

The heat generated per unit length doesn’t vary with total length. The total heat generated is of course proportional to length. This only becomes a problem if a long piece of cord is coiled up in a pile and insulated.

For the OP’s example, 14ga wire is .0026Ohm/foot. One foot of cord has two feet of wire so .0052Ohm. 12A squared is 144 so 144x.0052 = 0.75Watt/foot. For a 25’ cable that’s 19Watt for the whole cord, or 12Watt for 12ga wire.

-- Dave, Tippecanoe County, IN

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moosie

14 posts in 767 days


#11 posted 05-09-2019 07:31 PM

Thanks guys. The connectors determining the lower rating makes sense.

I hadn’t thought about the 12-3 not fitting in the strain relief / hole. I guess if it won’t fit, then I’ll plug the existing cord into a 10-15 foot extension cord.

Grizzly doesn’t mention lengthening the cable, but states a 12-3 extension cord is acceptable, 50 ft or less.

Either way I go, it seems I can just chop up a regular 12-3 125V extension cord.

View CarlosInTheSticks's profile

CarlosInTheSticks

395 posts in 793 days


#12 posted 05-09-2019 07:53 PM

No argument with your theory here, it’s your theory. Manufacturers recommendations stand out when ever I wire a machine, some of the heavier machines I have rebuilt came with heavier cable and they were on short cords, and I have always spent a little extra on wire to be safe rather than run close to the line. But thats my opinion.

-- "There are no utopias, chaos theory reigns, anyone who says different is selling you something"

View DBDesigns's profile

DBDesigns

220 posts in 418 days


#13 posted 05-09-2019 08:41 PM

FYI,
The way I approach my cords in the shop is to oversize them so I never have to worry about length. I always keep a few extra “power hoses” around in case I need to work far from the shop with a skill saw, chop saw, or compressor. Here’s a hint; HD sells various gauges of stranded wire cords by the foot and connection ends in different current ratings. I always assemble my own cords so I can determine the capacity and it costs way less. As far as strain relief, I would just increase the size of the hole in the tool case and use a strain relief from the electrical section.

-- I remember when Grateful wasn't Dead

View sgcz75b's profile

sgcz75b

72 posts in 181 days


#14 posted 05-09-2019 11:37 PM

Recently bought a GO858 jointer. I needed it by a certain island wall where I didn’t have a 220 outlet. Since I have several other 220 tools all using the identical plug I simply made a 16’ 10 gauge 2 wire (with ground wire) extension cord. Ran it from an existing 220 receptacle up the wall, over, and down EMT to the work island where I secured it in a receptacle box.

Easy to do and you don’t have to replace the jointer cord. Cost about 10 bucks for the 220 plug and receptacle as I already had plenty of 10 gauge wire, EMT, and receptacle box.

If it was me wanting a 25’ 220 extension cord, I’d go with 10 gauge. You paid $1800.00 for the jointer. This isn’t the time to count pennies for an extension cord.

-- "A dying people tolerates the present, rejects the future, and finds its satisfactions in past greatness and half remembered glory" - John Steinbeck

View ibewjon's profile

ibewjon

683 posts in 3214 days


#15 posted 05-10-2019 03:38 AM

E (voltage) x I (current in amps ) = P (power in watts ). 1000 watts equals 1 kilowatt. If you double the voltage, current is reduced to half, and watts used is the same with either voltage. The cost savings with higher voltage comes from reduced wire and conduit size. ( Manufacturers can use smaller cord than code allows us to use. ) For a short cord, 12 is ok, but a heavier 10 awg cord is cheaper than a new motor.

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