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240 Volt electrical question

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Forum topic by Julian posted 11-16-2015 02:12 AM 874 views 0 times favorited 24 replies Add to Favorites Watch
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Julian

1033 posts in 2150 days


11-16-2015 02:12 AM

Topic tags/keywords: question

I just purchased a 3 hp Jet table saw and the plug has 3 prongs. I have a 240V circuit in the garage but that outlet has 4 prongs (for a 5hp drum sander). The outlet for the drum sander has 2 black wires, 1 white, & 1 green.
I want to install another outlet next to this one. If is use 1 of the black wires, the white and green will that work?
I don’t want to make a mistake and burn up my TS motor.

-- Julian


24 replies so far

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johnstoneb

2143 posts in 1632 days


#1 posted 11-16-2015 02:25 AM

Given the question you’re asking and how you are asking it. Hire an electrician. He’ll wire it up in a few minutes not to much money and won’t burn your house down or electrcute You.

-- Bruce, Boise, ID

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TheFridge

5764 posts in 946 days


#2 posted 11-16-2015 02:26 AM

Use both blacks for 240v

1 black and 1 white will prob be 120v

I’d check with a meter.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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MrUnix

4203 posts in 1658 days


#3 posted 11-16-2015 02:27 AM

Typically, the two blacks should be the hots, the white is neutral and green is ground. A meter can quickly verify. If so, then you would use the two blacks (hots) and green ground. The white neutral will be unused.

Cheers,
Brad

-- Brad in FL - To be old and wise, you must first be young and stupid

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crank49

3980 posts in 2430 days


#4 posted 11-16-2015 02:45 AM

You can’t depend on the color of wires to determine voltage.
No way to know whether the person hooking them up was an electrician or some body else like you that has to ask this question.
Hire an electrician.
Or, at the very least buy a voltmeter and a book on wiring.

-- Michael: Hillary has a long list of accomplishments, though most DAs would refer to them as felonies.

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Julian

1033 posts in 2150 days


#5 posted 11-16-2015 04:47 AM

The 240V outlet was installed by an electrician. I’ll check with my meter. This is not rocket science. Thanks for the advice.

-- Julian

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DIYaholic

19169 posts in 2134 days


#6 posted 11-16-2015 04:51 AM

True this is not “rocket science”....
However, I’ve seen live video of NASA rockets exploding!!!

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

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TheFridge

5764 posts in 946 days


#7 posted 11-16-2015 05:37 AM



The 240V outlet was installed by an electrician. I ll check with my meter. This is not rocket science. Thanks for the advice.

- Julian

No problem. Some are cautious. Some actually are electricians.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View rwe2156's profile

rwe2156

2187 posts in 940 days


#8 posted 11-16-2015 12:56 PM



You can t depend on the color of wires to determine voltage.
No way to know whether the person hooking them up was an electrician or some body else like you that has to ask this question.
Hire an electrician.
Or, at the very least buy a voltmeter and a book on wiring.

- crank49

What ^ he said X 10!!

My advice: if you’re electrician tells you its ok, get another one!

-- Everything is a prototype thats why its one of a kind!!

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WoodNSawdust

1417 posts in 636 days


#9 posted 11-16-2015 01:22 PM

Most (some?) electrical codes require 240V to be a direct run from a single outlet back to the breaker box. At least here in Missouri that is the rule.

Your idea will work, assuming you use the correct wires, but may not be code. This will cause problems if you get an electrical inspection or if you make an insurance claim.

As others have said it is better to hire an electrician.

-- "I love it when a plan comes together" John "Hannibal" Smith

View HokieKen's profile

HokieKen

1735 posts in 598 days


#10 posted 11-16-2015 02:28 PM

If it were me, I’d either replace the plug on the table saw or make a pigtail to adapt that plug to the existing outlet. Much cheaper than paying an electrician to run another outlet.

And, I think WoodNSawdust is correct. If I remember correctly, your only allowed 1 outlet/circuit for 230V.

-- Kenny, SW VA, Go Hokies!!!

View hhhopks's profile

hhhopks

645 posts in 1837 days


#11 posted 11-16-2015 03:38 PM

I like Kenny’s idea, a conversion plug and should be the cheapest. There will be no wire from the saw to the neutral wire (white) position. You can only operate one tool at a time. Right?

-- I'll be a woodworker when I grow up. HHHOPKS

View Fred Hargis's profile

Fred Hargis

3926 posts in 1953 days


#12 posted 11-16-2015 04:21 PM

You guys that think you can’t have multiple outlets on a 20A/240V circuit aren’t referring to the NEC ( I think 30 amp are OK as well). There is (was) nothing in there that prohibited multiple 240V outlets on a single circuit, although some localities might have stuck that in their requirements.

-- Our village hasn't lost it's idiot, he was elected to congress.

View HokieKen's profile

HokieKen

1735 posts in 598 days


#13 posted 11-16-2015 05:08 PM



You guys that think you can t have multiple outlets on a 20A/240V circuit aren t referring to the NEC ( I think 30 amp are OK as well). There is (was) nothing in there that prohibited multiple 240V outlets on a single circuit, although some localities might have stuck that in their requirements.

- Fred Hargis

You’re right (for VA anyway). I just looked at the code. I thought line-line circuits could only service 1 outlet but according to VA code, as long as all ungrounded conductors are opened simultaneously by the breaker (2-pole breaker), you can run multiple outlets.

I’d probably still opt for a new plug or converter but since it’s a conduit install, it would be a simple thing to throw a junction box in there and run a second outlet.

-- Kenny, SW VA, Go Hokies!!!

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Fred Hargis

3926 posts in 1953 days


#14 posted 11-16-2015 05:33 PM

When I wired my shop I put in 5-240V circuits. One for the DC is dedicated, but the others (3-20A, 1-30A) are all multiple outlet circuits….and when I did it I checked the NEC and found no problems with the practice.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Julian's profile

Julian

1033 posts in 2150 days


#15 posted 11-16-2015 05:43 PM

Kenny; I will use your idea. Just change out the plug on the cord to fit the existing outlet. The neutral prong will not be connected on the TS cord. I will never need to use the table saw and drum sander at the same time. This will be less work and $. Thanks Kenny.

-- Julian

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