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-   -   grounding to water pipe question (http://www.diychatroom.com/f18/grounding-water-pipe-question-5458/)

eastvantrading 12-18-2006 10:37 AM

grounding to water pipe question
 
Hi everybody,

I have an older house with, among other outdated wiring issues, several open-ground circuits. I understand that this is generally ok and safe. Everything has worked fine for years.

I recently bought and installed a surge-protection/UPS/backup for my computer that has a 'building wiring fault' indicator, and this indication reminded me that things might not be as up to date as need be. Basically, this unit I bought for my computer is useless unless I remedy this 'fault'.

My question is this: I think the reason for this, is that this receptacle is open-ground. Very close by, there is an exposed copper water pipe (main service) which extends underground, through the earth toward the city connection. Would I be able to simply run a ground wire to ths pipe and clamp it in place to effectively ground this circuit?

I appreciate your help.


Evan

Christopher 12-18-2006 11:37 AM

eastvantrading,
Quote:

...I understand that this is generally ok and safe
You are misinformed here.

It is never safe for the third prong of a receptacle to be open, never!

The Underwriters Laboratory's safety rating on equipment with a 3-prong plug is entirely based on the ground connection not being open.
Quote:

Everything has worked fine for years.
I don't doubt this. A ground connection is to provide safety in the rare event that a piece of equipment develops a fault. The longer you go without a fault, the more likely that one will occur.

Computers require grounding for electrical noise suppression in addition to user safety.
Quote:

Would I be able to simply run a ground wire to this pipe and clamp it in place to effectively ground this circuit?
This would have some degree of effectiveness but I do not recommend this. The ground connection should be sourced by the main service so that all grounds are at the same potential, and no anomaly in your plumbing system turns a pipe into a live wire via a faulty appliance.

...Christopher

Sparky Joe 12-18-2006 11:49 PM

Quote:

Originally Posted by Christopher (Post 27313)
eastvantrading,You are misinformed here.

It is never safe for the third prong of a receptacle to be open, never!

The Underwriters Laboratory's safety rating on equipment with a 3-prong plug is entirely based on the ground connection not being open.I don't doubt this. A ground connection is to provide safety in the rare event that a piece of equipment develops a fault. The longer you go without a fault, the more likely that one will occur.

Computers require grounding for electrical noise suppression in addition to user safety.This would have some degree of effectiveness but I do not recommend this. The ground connection should be sourced by the main service so that all grounds are at the same potential, and no anomaly in your plumbing system turns a pipe into a live wire via a faulty appliance.

...Christopher

I do not agree with all this especially the fact that 2 prong receptacles are unsafe. Most every tool I have is double insualted and evreything thing else in the house is two prong except for appliances in the kitchen and bathroom where a GFI replaces the need for a grounded receptacle and is far more safe. My computer also needs a ground prong, but I'll get to that.

Your cold water pipe is not an effective ground. A ground is a direct electrical link back to the transformer from where the power was created(on the power pole behind your house). Before it hits your meter this wire is called the neutral, at the meter it's purpose remains the same, but it's name changes to 'grounded conductor', at this same place a new wire is created called the 'grounding conductor' this would be the third prong on your receptacles. At your meter and only at the meter the grounded and grounding conductors are connected also the bonds to your water pipe and ground rod are connected here, this connection is called the target or "bullseye". Keep in mind the water pipe or ground rod or any other grounding electrode are only there to provide lightning protection and no other protection or stability in you electrical system.

What you need to do is somehow run a piece of #12 wire, bare or insulated, in anyway you can see fit back to your meter and connect it to the neutral bus(if you can follow the wire from ground rod, or water pipe connect it to the same place).

Speedy Petey 12-19-2006 05:43 AM

.....

Christopher 12-19-2006 09:12 AM

Sparky Joe,
Quote:

I do not agree with all this especially the fact that 2 prong receptacles are unsafe
I never stated the above as you attribute me having said.

I said that 3-prong receptacles with an open ground are unsafe. Equipment with 3-prong plugs is not double insulated.

Furthermore, grounding is no longer for safety only. Nearly all electronic today contains an electrically noisy switch-mode power supply. If the specific piece of equipment has a 3-prong plug then grounding is required to meet FCC, CE and other agency requirements for low EMI/EMC/RFI noise.

If you disagree with anything that I have stated please provide an NEC code reference.

...Christopher

joed 12-19-2006 06:14 PM

It is permissble under the NEC(I can't give you a code) to have GFCI protected three prong receptacles with no ground present. This will not make a device such as a surge suppresor, that requires a ground, work properly but it is permissible.

eastvantrading 12-20-2006 09:49 AM

thanks and update
 
Thanks to everyone who replied. It was educational. Good news, it turns out - I finally looked behind the receptacle (it's too dark to turn off breakers & work these evenings) and it turns out a ground wire does exist and wasn't connected. I hope this is the case with all my 'open' grounds'.

Best,
Evan


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