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Sizing my TS power cord for 240V

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Forum topic by moosie posted 07-27-2017 03:22 AM 1351 views 0 times favorited 26 replies Add to Favorites Watch
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moosie

8 posts in 179 days


07-27-2017 03:22 AM

Hi folks,

First time poster here.

I am awaiting delivery of my new Grizzly G0771Z table saw. Pretty excited. Serious upgrade from the little 35 year old Makita job saw with a rusty so-called fence.

Anyway… The saw runs on either 120 or 240V, single phase, and is pre-wired for 120. I intend to run on 240V. It comes with a 6’ power cord, 5-15 plug, 14 AWG. Full load is 15A on 120, and 7.5A on 240.

Obviously I’ll need to replace the connector with a 6-15. At the same time, I really wish it was a 10’ cord. I do not wish to starve my saw of current. Can someone help me properly size the new cord? I’m sure there’s a formula addressing length, voltage, amps, etc, but I haven’t been able to find one.

Once I know what I need, then I’ll either buy a pre-made cord, and cut the female end off (to wire the TS switch), or order one from http://stayonline.com or similar.

Tag on question, while I’m on the topic. I also need to add a 240V circuit to the garage / shop. I don’t have DC yet, but it’s a matter of time. I anticipate DC and TS will be the only two machines I’ll run on 240, and the DC I’m looking at pulls 9A max. With the TS, that’s 16.5A. Do I need a 30A circuit, or will 20A be OK?

Thanks!


26 replies so far

View MrUnix's profile

MrUnix

5973 posts in 2032 days


#1 posted 07-27-2017 03:27 AM

14 gauge would be fine. Don’t run multiple machines on a single 240v circuit.

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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moosie

8 posts in 179 days


#2 posted 07-27-2017 03:36 AM

Thanks.

My panel only has five open slots. One will be the 20A 120 that I badly need for smaller tools. DC and TS will each consume a pair.

What if I eventually add one more 240V machine? The usual single-man caveat applies – I can only run one thing, plus DC, at a time. Is it OK to put all my tool machines on the one 240V circuit, as long as I only run one at a time, and the DC is isolated to it’s own? Or is this a violation?

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Loren

9602 posts in 3480 days


#3 posted 07-27-2017 03:56 AM

You can install duplex breakers to increase the
capacity of your panel. With duplex breakers
you’ll have 10 slots equivalent if you want to
replace all the breakers and your two 240v lines
will take a pair each. It’s not that complicated
to set it up but more than I can explain clearly
here. Duplex breakers may be controversial
among electricians. I’ve used them for years
with no problems.

I’ve always had setups where each 240v outlet
was on its own circuit so to run another machine
switching plugs was needed.

View ArtMann's profile

ArtMann

677 posts in 649 days


#4 posted 07-27-2017 04:32 AM

Running multiple 240VAC outlets on a single circuit is not prohibited in any place I have ever done any wiring. If you are going to call in an inspector, you should check with him ahead of time to avoid problems. I have encountered some pretty strange requirements before. There is no engineering reason that I can think of to run multiple circuits to multiple machines if you aren’t going to use them at the same time. Even if you do, the worst that can happen is your breaker will open up after several seconds. My shop is wired for multiple 240VAC outlets on a single circuit and in 12 years or so, I have never had a problem. I do have my air compressor and dust collector on unique circuits because you never know when the compressor will cycle and a dust collector is always used with some other machine.

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Madmark2

370 posts in 421 days


#5 posted 07-27-2017 05:08 AM

Ummmm, don’t cut the cord. Order the 240v kit.

I wired a 6-20 receptical on a 20A sub panel with 12/2 w/gnd since I was not going to split the 220 into a pair of 110’s

M

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WhyMe

909 posts in 1394 days


#6 posted 07-27-2017 04:11 PM



Running multiple 240VAC outlets on a single circuit is not prohibited in any place I have ever done any wiring. If you are going to call in an inspector, you should check with him ahead of time to avoid problems. I have encountered some pretty strange requirements before. There is no engineering reason that I can think of to run multiple circuits to multiple machines if you aren t going to use them at the same time. Even if you do, the worst that can happen is your breaker will open up after several seconds. My shop is wired for multiple 240VAC outlets on a single circuit and in 12 years or so, I have never had a problem. I do have my air compressor and dust collector on unique circuits because you never know when the compressor will cycle and a dust collector is always used with some other machine.

- ArtMann

International Residential Building Code prohibits multiple receptacles on circuits greater than 20 amps. So multi-outlet 20A 240V is okay, 30A and up not okay.

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moosie

8 posts in 179 days


#7 posted 07-28-2017 11:25 AM

Thanks guys. I appreciate the good information.

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jonah

1442 posts in 3131 days


#8 posted 07-28-2017 11:40 AM

Cutting the plug off the end of the cord is perfectly fine. 14AWG is fine for 7.5A, but you lose nothing other than a little money by using bigger wire. It’s up to you.

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moosie

8 posts in 179 days


#9 posted 07-28-2017 08:16 PM


Cutting the plug off the end of the cord is perfectly fine. 14AWG is fine for 7.5A, but you lose nothing other than a little money by using bigger wire. It s up to you.

- jonah

The cord coming on the saw is only 6 foot. I’m going to need to lengthen it anyway. I hear all these warnings about running a machine like this on an extension cord, so I’m being careful.

For a 7.5 amp load, roughly how long can my cable be before I need to move up to 12 AWG? 20 feet? 50 feet?

Thanks.

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jonah

1442 posts in 3131 days


#10 posted 07-28-2017 09:44 PM

The wiring chart will say something like 30-50ft for 14AWG, but honestly I’d just make a 10 foot power cord with 12AWG and be done with it. Again, all you lose is a bit of cash moving to thicker wire, and you give yourself more of a safety margin if you need to go longer at some point via an extension cord.

View bigJohninvegas's profile

bigJohninvegas

382 posts in 1295 days


#11 posted 07-28-2017 10:02 PM

That new Grizzly saw will come with a manual that will tell you what wire size it needs.
I have a grizzly 17” bandsaw
While it came prewired for 220. It had no plug and the cord was to short for what I needed.
The instruction manual had all the specs for what was required for both cord and plug.
It only had about 6’ of cord and I needed a cord about twice that length. Instead of an extension cord I chose to replace the short cord. Very easy. And good instructions.
A 10 foot cord will be no problem. Even

-- John

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moosie

8 posts in 179 days


#12 posted 07-29-2017 12:10 AM



That new Grizzly saw will come with a manual that will tell you what wire size it needs.
I have a grizzly 17” bandsaw
While it came prewired for 220. It had no plug and the cord was to short for what I needed.
The instruction manual had all the specs for what was required for both cord and plug.
It only had about 6 of cord and I needed a cord about twice that length. Instead of an extension cord I chose to replace the short cord. Very easy. And good instructions.
A 10 foot cord will be no problem. Even

- bigJohninvegas

This is why I asked. I read the manual, and while it describes converting from 120 to 240, and describes proper grounding, it does not specify cord length or wire gauge, except to say what it comes with, and that one shouldn’t use an extension cord, but if you’re going to, then keep it below 50 ft, and at least 12 AWG.

Since the plan is to create a new direct-wired power cord, and not an extension, I wasn’t sure.


The wiring chart will say something like 30-50ft for 14AWG, but honestly I d just make a 10 foot power cord with 12AWG and be done with it. Again, all you lose is a bit of cash moving to thicker wire, and you give yourself more of a safety margin if you need to go longer at some point via an extension cord.

- jonah


I don’t know where that wire chart is, but you make a good point. I like margin of safety.

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Holbs

1721 posts in 1862 days


#13 posted 07-29-2017 12:17 AM

any machine power cord I purchase (have done such for my PM66 saw and a 220v extension cord which I found out having a metal box is not a good idea, but I am just bringing up the SOOW material here) is that thick black rubber that you can run a steam roller over (SOOW material). http://lumberjocks.com/topics/129010

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter

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MrUnix

5973 posts in 2032 days


#14 posted 07-29-2017 12:32 AM

IMO, you won’t accomplish anything by going up to 12ga from 14ga other than spending more money, particularly on a permanent fixed cord that will only be used for that purpose. 14ga can do 7.5A@240v easily up to 50 feet (you could actually get by with 16ga!). At 50ft, 14ga would have approx. a 1.9v drop, 12ga would be approx. 1.2v. For a 10-15 foot cord, there is virtually no difference between the two (~1/4 of a volt or so).

Cheers,
Brad

-- Brad in FL - In Dog I trust... everything else is questionable

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moosie

8 posts in 179 days


#15 posted 07-29-2017 12:39 AM



IMO, you won t accomplish anything by going up to 12ga from 14ga other than spending more money, particularly on a permanent fixed cord that will only be used for that purpose. 14ga can do 7.5A@240v easily up to 50 feet (you could actually get by with 16ga!). At 50ft, 14ga would have approx. a 1.9v drop, 12ga would be approx. 1.2v. For a 10-15 foot cord, there is virtually no difference between the two (~1/4 of a volt or so).

Cheers,
Brad

- MrUnix


See, I don’t have a table, or the knowledge to figure that out.

What you say makes me wonder why Griz basically contradicts with their extension cord mantra. In fact, I was very surprised to see that the stock power cord was only 14 gauge, because for the “shortest possible” extension they’re recommending 12. That’s how I got to wondering if there was some loss just because it’s extension vs direct.

I wish they’d simply have said “when you convert to 240, construct your cord as follows…”

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