EMT as grounding

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So what does the code say to do when there is no ground wire? Pig tail from the box or ground to the cover plate screw which is acceptable?
 
maybe i should not put my two cents in here but i have seen alot of seperated conduit caused by many different factors.. the steel connectors are great but the old die cast.... well try and tell your helper that tightening them to much strips em out... lol. i agree with jim here. better to add it .
 
dingokangaroo said:
j-boxes where not designed to ground at the ring cover screws... and your answer would be pigtail from a green machine screw in the back of the box
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This is being picky but, there is no requirement for the screw to be green.

Roger
 
What is EGC? If you can use EMT as a ground, then why is a ground wire required by the NEC, assuming it is.


External Grounding Conductor?
 
Eddy Current said:
What is EGC? If you can use EMT as a ground, then why is a ground wire required by the NEC, assuming it is.


External Grounding Conductor?
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Equipment Grounding Conductor and a wire type is only required in some specific areas otherwise just one of the types listed in 250.118 is required.

Roger
 
I have seen a fair number of EMT conduit connections that have come loose so I can understand why some are skeptical of EMT as an EGC. I am too. Having said that, the code clearly allows it most of the time.
 
iwire said:
I find corroded copper conductors in any location that they get wet, particularly under the steel spring of a wirenut.
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Next time you run across one of these look very closely at the actual interface points between the copper conductors. You may find that they are somewhat tarnished but the corrosion does not extend to the actual electrical connection.
 
petersonra said:
Next time you run across one of these look very closely at the actual interface points between the copper conductors. You may find that they are somewhat tarnished but the corrosion does not extend to the actual electrical connection.
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Actually it does extend into the connection and if the wire is stranded it will often extend quite far back under the installation.
 
weressl said:
In real life corrosion of copper wires usually only occurs when aggressive chemicals are present.
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iwire said:
And you know this from all your years out in the field servicing electrical installations. ...:grin:
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weressl said:
Yep, about 40 years.
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So do you design electrical systems or do you service them?

As as service guy you must be very inexperienced if you think it always takes 'aggressive chemicals' to cause corrosion of copper conductors.

Maybe come up here to New England and I can show you many examples.:cool:

I am still waiting for those for a link to these ...

weressl said:
The copper connectors are designed to be flexible and to maintain the pressure under the thermal cycling.
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iwire said:
I find corroded copper conductors in any location that they get wet, particularly under the steel spring of a wirenut.
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I have found the same. While humidity alone is not a corrosive agent, it tops the list of variables that are important to the corrosion process. Reactive chemicals are close to the top and temperature is near the bottom of the importance stack. To state the obvious to some, you will find that, as a general rule, copper tarnishes at a much faster rate in industrial environments.

A high humidity environment is not necessarily the only critical factor as one must control both critical pollutants and the humidity. A good example of control in a high humidity environment is the goo in the wirenuts rated for wet locations.

iwire said:
I am still waiting for those for a link to these ...
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I don't have a link but I will tell you that copper connectors are indeed designed to give better mechanical characteristics. Copper alone has poor spring properties, but by adding beryllium (less than 2%) or phosphorus, you can get a very good spring connector. These are also good up to around 150?C. Belleville washers are usually made of steel but you can get them made of bronze and copper alloys.
 
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