Re: [CAD_CAM_EDM_DRO] Re: power supply connection issues

In a message dated 10/16/2002 9:02:19 PM Central Standard Time,
jagco1998@... writes:

> Is the grounded green wire to grounding rod really necessary? Will not
> using this "G" terminal hinder the performance of the PS or cause it to
> malfunction?(ie. just using L and N to power the supply) I realize that I
> probably sound like an idiot , but I payed good money for this used Power
> supply, and I do not want to burn it up before I even get to use it
> throwing some chips!
>

Jim: The "G" wire ("Ground", Green in the USA, and Green with a yellow
stripe in Europe) is "normally" not conducting any current. It is present
for "safety". If there is a "short circuit" in the machinery from "L" (aka
"hot") to the chassis, etc., this Green wire, then, conducts this current to
GROUND, [hopefully-] blowing the breaker or fuze. Oh, it might also serve to
"drain" EMI nasties, but not really much "measureable" current would be
involved in that.

I guess if you live in a building with only TWO conductors to each outlet,
you have then NO clue what a "GFI" is. In NEW houses, there is a "Ground
Fault Interruptor", usually a strange-looking duplex-outlet with a couple of
funny push-buttons between 'em, in the "main bath", where one plugs in
electric shavers and/or hair-dryers. THAT "GFI" has an ELECTRONIC sensor
built into it which COMPARES the current ("amperage") flowing IN via the
"hot" or "L", to that flowing OUT via the "N" Neutral, back to the [ground]
in the electrical panel box where all the "breakers" are. If a VERY FEW
milliamperes more current flows IN than flows OUT, it means SOME of the
current is "escaping" "outside the circuit", such as when you drop your dryer
in the bathtub and kill the child therein, etc. The GFI then instantly OPENS
the circuit (as does a current overload which would blow the fuze), and this
(hopefully) saves the child in the bathtub who pulled his AC-powered radio
into the bath, while attempting to change the hip-hop station.

My meaning for all this "story" is to point out that there IS a reason for
that "green wire", and, while most appliances WILL operate if it is not
connected, doing so is DANGEROUS and "19th Century mentality" and I would
just as soon carry a COCKED and loaded automatic pistol with the "safety off"
in my briefs! VERY CAREFULLY! NOT!

Further: GROUNDING the "box" or "chassis" of your appliance (or the metal
body of your hand-held power-drill, etc.!) will certainly NOT "smoke" your
just-purchased toy, but may-well SAVE YOUR LIFE!!!!

A number of the "other guys" in here have well-described what "N" and "L" and
"G" mean, but I do not recall anyone really saying much about the "value"
(i.e., NECESSITY!!!) of the "G wire"!!! NEVER fail to USE it properly!
You would be WELL-advised to spend some coin and have a professional
electrician install "three-hole" outlets and "grounded" Romex in your
ancient house, particularly in the kitchen, bath(s), and shop-areas!!!!
Really! Sincerely!!!!

Jan Rowland


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