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Electrical question

S

Stephen Newell

Well-known Member
I have a table saw that runs on 220v and the cord is only three prong with two hot and a neutral. Is there any benefit of putting a wire with a four prong plug on it and attaching a ground wire to the body of the machine.
 
Its always a good idea to ground the frame of any device, IMHO. Assuming the socket you're plugging into is 4 prong and is grounded back to the panel, of course.

Got fired from a carpentry job one time because I complained about being shocked by the boss's ancient ungrounded circular saw while using it in the rain.
 
If you are not getting shocked by touching the table saw, then don't worry about it. If you are getting shocked, do as you say. Run a wire from frame of table saw to ground (cement floor, dirt, etc.). I use to do it all the time when working outside in elements. Also, if you're getting shocked, check for wrong polarity in electrical wiring.
 
The 220v you have now is the voltage difference between the two hots (+110 to -110 as they alternate out of phase with each other).

You only need a fourth conductor if you want 110v at the saw and use either of the hot leads to get it. In that case you would need to add a neutral; you already have a ground.
 
A ground is of course a good thing!
However, people so often get a neutral and a ground wire confused, it is hard to advise you without seeing what you really have.

If the saw has no 110v features (electronic controls, clock, etc) then there is no need for a neutral on a pure 220v machine, and you likely already would have the two hots plus a ground, with no neutral?

--->Paul
 
Mike, better to be fired than end dead like a friend of mine's brother using an electric drill that the ground pin cutoff. Company got a big fine but someone died. That was 30 years ago.
Now, my neighbor works in construction and he says the Inspectors are always doing work site spot checks of electrical equipment, checking for damaged and ungrounded power cords and equipment. Cordless and air tools have eliminated some of the problems.

JimB
 
Without being there I have to take an "educated guess" at what you have which may or may NOT be what your post indicated. I just cant say settin here from your post alone, sorry.

If you really have a straight 220 volt (i.e. NO 120) device/saw and it has a factory installed 3 wire cord and/or plug Id GUESS THAT THIRD WIRE (especially if its bare or green instead of white) is the safety equipment GroundING Conductor NOT a Neutral !!!!!!!!!!!!

Put an ohm meter or continuity tester on that third wire and see if it's electrically attached to the saws outer conductive metal case/frame??? IF SO, ITS THE SAFETY EQUIPMENT GROUND ING CONDUCTOR NOT A NEUTRAL.

The ONLY reason you would need 4 (2 Hots, Neutral, Equipment GroundING Conductor) wires is iffffffffffffffff the device requires BOTH 120 and 240 volts. THEN AND IF SO YESSSSSSS USE 4 WIRES

HOWEVER if its straight 240 (NO 120) all you need is 2 Hots and the Equipment GroundING Conductor which is attached to the outer conductive metallic case/frame. Similar, if it were 120 volt ONLY, again all you need is 3 wires, Hot, Neutral, Equipment Ground

THE SAFETY EQUIPMENT GROUND ING CONDUCTOR ATTACHED TO A DEVICES OUTER CONDUCTIVE METALLIC CASE/FRAME SHOULD ALWAYSSSSSSSSSSSSS BE USED REGARDLESS IF 120 OR 240 VOLT.......... IT CAN SAVE YOUR LIFE

NEVERRRRRRRRRRR MIX N MATCH OR USE GROUND FOR NEUTRAL OR NEUTRAL FOR GROUND IT CAN GET YOU KILLED THEY ARE NOTTTTTTTTTT REPEAT NOTTTTTTTTTTTTT THE SAME. The Neutral is a live return current carrying GrounDED Conductor, the Equipment Ground is a GroundING Conductor dedicated to provide a direct low resistance current carrying path FOR FAULT CURRENT ONLYYYYYYY so the breaker can trip and de energize the circuit and save your life.

The live current carrying Neutral is insulated for a reason, you wouldnt peel off the Neutral insulated jacket and touch the wire would you ??????????? BUTTTTTTTT if you start mixin n matching and using Ground for Neutral or Neutral for Ground THAT COULD BE WHAT YOURE EFFECTIVELY DOING

If I missed anything hopefully other professional electricians, electrical techs, and engineers (NOT Billy Bob and Bubba who wired their own houses over a case of beer lol) can add to this

John T Longgggggggg retired Electrical Engineer and yes rusty on latest NEC so no warranty, but believe all the above is still true and potentially life saving advice
 
Good Morning Oliver, I have a friendly and hopefully helpful comment on your statement: "Run a wire from frame of table saw to ground (cement floor, dirt, etc.). I use to do it all the time when working outside in elements."

While its true, that may indeed prevent you from feeling any shock THAT DOES NOT CURE THE HAZARDOUS PROBLEM if a hot wire is shorted the the metal case/frame. It stops the shock because theres a very low resistance and low voltage across the wire you ran to ground thats in paralell with your body.

WHAT REALLY NEEDS TO BE DONE TO STOP THE SHOCK AND MAYBE SAVE YOUR LIFE is run a third wire Equipment GroundING Conductor (usually bare or Green) from the device back to the Equipment Ground Buss in the Panel. That way the FAULT CURRENT caused buy a hot wire against the case/frame has a low resistance path back to the panel so the breaker can trip, de energize the circuit and save your life. The earth or concrete ect alone (i.e. no copper ground wire)is usually too high of a resistance to allow enough current to flow that trips say a 20 amp breaker so the case/frame remains HOT and you could still be killed since that only takes maybe 30 to 50 milliamps of current thru your old ticker ouchhhhhhhhhh.......

Fun chattin with ya, hope this helps

John T
 
Take a good look in your main box remove the inside cover and on one or both sides you will see an aluminum bar that it is bolted directly to the box. Now look to see where your white neutral wire and the bare copper wire are secured. This will answer a lot of questions as to what they both do. GO TO THE GROUND WIRE WHICH IS CONNECTED TO THE GROUNDING ROD.
So what does the bare copper wire do. Hey your guess is as good as mine but I bet Ol John T can tell you if he has enough time and space available.
Walt
 
Hey there Walt you rascal, I just came in to take a break from RV preventive maintenance before my Sunday afternoon nappy (I dont like to hit er quite so hard on the Sabbath dont ya know)lol so I have a few minutes.

Yeppers, youre on track, in the Main Service Panel the Ground Buss and the Neutral Buss are bonded together but thats NOTTTTTTT true if you feed a sub panel off of the Main. Also at EITHER the weatherhead riser orrrrrrrrrr the meter base orrrrrrrrrr the Main Service Panel, a Grounding Electrode Conductor (bare No 4 Copper Wire) is tied to the NEUTRAL and its leads outside to a GROUNDING ELECTRODE such as driven into earth copper rods (called made electrodes) or metal water pipes etc etc.

The Neutral, since its BOTH a live current carrying conductor for normal return current and its tied to mother earth with that Grounding Electrode Conductor, IS CALLED A GROUN DED CONDUCTOR.

The equipment Ground (green/bare 3rd wire) is called a GroundING Conductor and its ONLY purpose and the ONLY time it conducts is TO CARRY FAULT CURRENT back to the panel so the breaker trips and saves your life as opposed to you touching that hot frame/case and fault current flowing through your old ticker n you wakin up dead

Nap time

Ol John T and all
 
(quoted from post at 06:28:45 11/18/12) Its always a good idea to ground the frame of any device, IMHO. Assuming the socket you're plugging into is 4 prong and is grounded back to the panel, of course.

Got fired from a carpentry job one time because I complained about being shocked by the boss's ancient ungrounded circular saw while using it in the rain.
Click to expand...

A union would have mandated that the equipment be safe and that you not be fired for not wanting to use faulty equipment.
 
The receptacle for the cord the saw has, has only a place to attach the red, black and white wire like a air conditioner. The bare wire is just coiled up in the box unused. I was wondering if it would be beneficial to change the cord on the saw so a ground wire could be attached to body of the machine or whether the white wire it was engineered with was just as good.
 
Basically all I’m thinking about doing is change the wiring so the bare wire at the receptacle is attached to the body of the saw. Right now it’s just coiled up inside of the box doing nothing because there is only room for three wires on the 220v receptacle. About 30 years ago I got a major shock on one of these saws and I’ve always wondered if they could be improved on.
 
YES if its straight 220 i.e. NO 110 used, IT WOULD BE BENEFICIAL PLUS COULD BE LIFE SAVING if you re wired so the conductive case/frame is bonded to a wire that leads back to the Ground Buss in the Panel (Normally thats the third wire ground, normally green or bare). NOTE when you use the wrong colored wire, you should get some plastic tape of the correct color and put on the ends!!!!!!!!!!!!

The correct receptacle is a two pole three wire grounding type, 2 poles for the 2 hots 220 volts red n black and the third is the green safety equipment ground wire.

John T
 
You're ate up....You should really try to drop in and visit reality once and a while if you can find your way back there. You've heard of reality....That's where people tell the truth about unions and not the flavor of the day cool aid version.
 
When I did work union construction, the general contractors I worked for had some of the most antiquated, delapidated, old fashioned JUNK tools and equipment. Since union work is all about taking as much time as possible to do mediocre work at the highest possible cost, they weren't at all concerned about the quality or condition of equipment. The non union contractor I work for now has top notch, high quality equipment so we can be productive. That's a concept unions just don't give a flip about. The only place where we lose out? We don't get a dose of cool aid every day either.
 
What an utter and total fabrication as you avoid facts and scramble to follow your emotions.
Get back under your boss"s desk.
"
 
Alwary wondered how the 2 110s can get out of phase when comming from the same high voltage line to a transformer.
 
Alwary wondered how the 2 110s can get out of phase when comming from the same high voltage line to a transformer.
 
I guess electricity can only travel in one direction on the two wires.
A neighbor had a satellite installed and the guy took the cable and put a circle in it before entering house. I ask what's that for.
The answer " to stop lightning as it can't travel around the circle.
Walt
Hey it's sounds as good as your answer.
 
Whoops forgot this one if you have a double insulated item with no ground how does it trip the breaker HUH.
Walt
 
Get more complicated. Buy and properly install a GFCI. They are available for 220volt. I have installed a few of them. Customers alway cry when they get the bill. I say how much is your life worth? No joke. Ever pull a dead man off a circuit. I have. Never forget it. Do you want the responsibility? Be safe as possible. Please. Dave electrician who had 4 licenses until prostate cancer hit
 
Thankyou. That is the answer I was looking for. It is straight 220V. Having nearly been electricuted just touching one of these saws not running it's such a simple fix to improve it.
 
You wrote this and it proves you do not understand. "only a place to attach the red, black and white wire like a air conditioner".
 
Simple, same way a 120V GFI operates. The GFI senses a current difference of 5ma or more of one insulated current carrying conductor vs. the other.
 
We could discuss multiplex signals on a single pair of conductors................
The sat cable loop is a simple air core inductive coil. The diameter and number of loop(s)will vary the XL to the DC pulse. While it does limit the peak voltage and current. The difference is like hitting an egg with a sledge hammer instead of a finishing hammer.
Ordinary electrical ground cables will be less effective conducting lighten pulses. When the installer errors and makes sharp/small dia bends in the ground cable.
 
Carpenter. 41 years so far. 39 years, 4 months in union. Now working in a right to work state so I don't have to pay extortionist's to have a job. Most everyone I work with opted out too. It's ridiculous to pay to have a job.
 
(quoted from post at 18:15:03 11/19/12) We could discuss multiplex signals on a single pair of conductors................
The sat cable loop is a simple air core inductive coil. The diameter and number of loop(s)will vary the XL to the DC pulse. While it does limit the peak voltage and current. The difference is like hitting an egg with a sledge hammer instead of a finishing hammer.
Ordinary electrical ground cables will be less effective conducting lighten pulses. When the installer errors and makes sharp/small dia bends in the ground cable.
Click to expand...
ELLO! The installer was trying to be a smart-A...it is called a drip-loop to keep rain water from running down the wire & into the structure! :roll:
 
Definitely not the case here. Some non union residential pays low, but there's plenty of non union commercial that pays scale or above, with good benefits, opportunity to move up within the company, and no dead spots between jobs. Like any occupation, there's opportunity for those with skill and ability. I've even found a number of VERY good paying residential jobs where skills required are above what the average carpenter can do.

Our local is 99% political. You have to play up to officers. They tell you how to vote, what to think, and who to treat like dirt. Not my cup of tea. I've seen guys who can't tell you which end of a claw hammer to hold and which end to hit a nail with who get favoritism. The union contractors I have a history with tended to accept poor craftsmanship and slow production, where the non union contractor I'm with now is all about excellence and staying ahead of schedule. With almost 40 years of union work, I left for a $8 an hour pay increase, 4 weeks PAID vacation, and the opportunity to work for a firm with the reputation of high quality work done ahead of schedule. And we don't have to work like slaves to get there. It's done by not wasting time. Popular phrase amongst union carpenters I used to work with was: "Expand the task at hand to fit the time available". Translation; Take every speck of time allowed no matter how much it bogs down production.
 
If it's a three prong plug and the machine operates on 240. Why would you think a neutral would be used?
Yet another time for the people here who refuse to believe the facts.
The neutral is an insulated current carrying conductor that is held to near earth potential.
The bare ground is usually a non current carrying system that hold the chassis of machines at earth potential for safety. In case the cases become energized due to a failure of insulation on current carrying conductors.
 
OK, I've been researching this and I didn't know a 220v machine only needed the two hot leads to run. Then what I have always been doing wiring this equipment is using the white wire for the ground because I run a seperate wire for each piece of equipment. This was someone else's shop I was shocked on. I guess the ground on that saw was interrupted somewhere either in the wiring or the plug. I think now if I wanted to do an overkill on ground wiring then grounding the machine twice would help.
 
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