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Use of EMT in grounding

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jlardino

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I am a new forum member. I am a fireman, not an electrician. I have strong general knowledge of electricity, but certainaly, I have had no formal training. Recently, I have become involved in a discussion in a model railroading forum about grounding control systems. Living in suburban Chicago my whole life, the use of EMT has been the standard in buildings around me. I know Romex and other stuff exist, and I am familiar with it and its uses, but not around here...The power sources we use for model railroading are commonly 120 VAC input and 15 VAC, 5A output which is connected to a Digitrax brand Command Station/Digital Signal Booster which issues track power and control signals to the trains. I asked if connecting the ground terminal of the control device to the screw that holds the outlet cover on serves to ground the system. Was told to connect it to the green wire. Replied that (of Course) "I don't have a green wire-only have conduit." Oh my God! What a discussion I have created in the Model railroad forum! It seems like no one has even heard of Cconduit (EMT)! Replies have almost entirely been of the flavor of "I have never heard of an entire home being wired with conduit, but maybe you are referring to that armored BX flex cable that used to be used extensively in house wiring. That type of cable has an uninsulated ground wire running through it that provides the continuous ground required by code.
However, taking what you said at face value, your home is probably not in conformance with the current National Electrical Code as far as
grounding practices are concerned."

So, I'm turning to those who should be able to educate me! What's up with conduit and why is it so foreign to so many? Seems like everyone thinks my house is a death trap!! Of course, I know it isn't, but as weird as they think I am, I guess I think they're weird for NOT using conduit!

Thanks to all in advance!

Your Friend,
John Lardino
Woodstock, IL
 
Re: Use of EMT in grounding

John
Just tell them that Chicago is wierd and that they should get over themselves. The US NEC specifically permits the use of Electro Metallic Tubing (EMT) as an Equipment Grounding Conductor (EGC).

250.118 Types of Equipment Grounding Conductors.
The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a combination of the following:
(4) Electrical metallic tubing.
--
Tom Horne

[ May 19, 2004, 03:52 PM: Message edited by: hornetd ]
 
Re: Use of EMT in grounding

John,
There should be a hole in the back of the box for a 10-32 ground screw.
If not, then use a ground clip.
Do not wrap the wire around the screw that holds the cover on.
Todd
 
Re: Use of EMT in grounding

Tell those that, as a result of the Chicago fire, as well as the fires at the Columbian Expo (Worlds' Fair that introduced electricity to the general public), Chicago has had an extremely conservative approach to electrical safety- and hasn't accepted those newfangled, unprooven things (like Romex, which came out in the '30's).
You can alos boast about how much easier it is to troubleshoot, repair, and alter a piped-in system. For example, it was no trouble at all to, back in the '60's, replace the two-prong receptacles with three-prong ones.
 
Re: Use of EMT in grounding

i honestly think it is much safer for a lot of reasons. however, not as the grounding conductor even though it meets code. my own home has all green wires pulled. i feel this way because couplers corode and come loose or were not tightened completely to begin with.

what i like best about rigid conduit is that if wires overheat you are covered. if something was wired improperly you are most likely covered(depending on how bad the mistake was). best of all you can drive a nail anywhere into any wall as long as you do not act like a gorilla! try that with nm.

ron g.
 
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