USA neutral wire does not equal ground

USA neutral wire does not equal ground

Postby zeeway » Wed Feb 12, 2014 10:00 pm

Last week, I lost the ability to zero my z axis through the touch plate, and it puzzled me for several days. The touch plate is connected to the controller at a connection that is designed for a touch probe. When the connection is grounded, a script stops the router bit and sets z to zero.
I checked the wiring and everything looked good there. Then I began to suspect a problem with my Gecko controller, which would have been very expensive to correct. But I ran a wire from the probe connection to ground and everything worked as it should.
Then it finally struck me…I had replaced my 110v Makita router (three prong plug) with a 110v Porter Cable router (two prong plug). I ran a separate wire from the grounding lug on the receptacle to the router, and finally it all worked as it should.
If this seems long-winded, I apologize, but it took me two days to figure this out. My hope is that this will save someone else some troubleshooting time. Moral of the story: the USA neutral wire does not equal a ground; and so, two-prong plugs are not equal to three- prong plugs.

Angie
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Re: USA neutral wire does not equal ground

Postby fretsman68 » Thu Feb 13, 2014 2:33 am

Excellent bit of info to post here as I could easily see this happening to many of us.

Thanks you for posting it!

Dave
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Re: USA neutral wire does not equal ground

Postby usLEDsupply » Thu Feb 13, 2014 5:24 am

if your plug is grounded correctly it should be the same as the netural (unless it is on an Arc Fault breaker as they monitor the neutral wire) the path may be longer but in the USA both the neutral and ground should go back to your electric panel and be connected together.

With a 3 wire plug the metal on the device/router should be connected to the 3rd prong "the ground" but
with a 2 wire plug the metal on the device/router shouldn't be grounded (if it were connected to the neutral you could possibly get electrocuted) so the bit would be floating until you ran the extra ground wire, so i would bet that is what the trouble is
(if you were to connect the router to the neutral wire i bet it would work just fine, it just wouldn't be a s safe)
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Re: USA neutral wire does not equal ground

Postby zeeway » Thu Feb 13, 2014 11:44 pm

My understanding is that a neutral may or may not have current flowing in it, depending what is happening in its circuit...if the circuit is live and working, the neutral should be seeing a flow of electrons. So while it ultimately is connected to a ground at a distribution panel, it cannot be assumed to be at "ground" potential; whereas a true ground is always at ground potential, unless, of course, something bad has happened and the ground has to act as a quickie safety valve for some rogue electrons coming through a short circuit. My further apologies to any electricians or electrical engineers that happen to read this.

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Re: USA neutral wire does not equal ground

Postby Ms Wolffie » Fri Feb 14, 2014 3:55 pm

2 prongs are double insulated and should not be earthed.
Don't ask me how I learned but it was expensive.
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Re: USA neutral wire does not equal ground

Postby ohiococonut » Sat Feb 15, 2014 12:47 am

Ms Wolffie wrote:2 prongs are double insulated and should not be earthed.
Don't ask me how I learned but it was expensive.
Cheers
Wolffie


That's not always the case, at least here in the U.S. There are many things with two prongs that are not double insulated. Unless you see the symbol which is a black square inside of a black box don't assume it's double insulated.
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Re: USA neutral wire does not equal ground

Postby Ms Wolffie » Sat Feb 15, 2014 2:18 am

Ah OK, I stand corrected :D
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