Gound conductor in EMT?

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  #1  
Old 12-20-04, 08:07 PM
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Gound conductor in EMT?

I know the EMT is supposed to be the ground...but...what if one of the box connectors gets loose or corroded? Seems the integrity of the ground is compromised.
So...is it customary/required to run a separate ground conductor in EMT?
Should the ground be connected in every box?
Ok to use bare or must I use green insulated? 14 ga or 12 ga?
Thanks.
Bill
 
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  #2  
Old 12-20-04, 09:12 PM
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The EMT can be used for the ground but quality installations will include a seperate ground wire. As you mentioned, connectors and coupling get loose and rust.
The ground must be connected to every box if there are splices, devices in that box.
Size depends on the largest concuctor in that box. I.e. if all the wires are #14, then you could use a #14 ground wire.
In conduit, we have always used green wire, not bare. You might be able to use bare but why would you want to strip all that insulation off?
~Peter
 
  #3  
Old 12-21-04, 11:20 AM
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I agree with separate ground conductor. It's permissable to use the EMT as the ground, but not always reliable. I personally would not use a bare conductor. (Don't know if it's OK, but I wouldn't do it.) For not much money per foot you can buy black, white, and green insulated THHN/THWN. I buy it by the 50' or 100' spool, one spool of each color.

Grounding to each box is only required with metal boxes. I prefer non-metallic boxes for interior work but in my garage everything was metal. Not necessary, but personnal preference. You do not have to bond non-metallic boxes, and you can't short the hot screw against a non-metallic box when installing or removing receptacles, light switches, etc.

When bonding to your metal box, if there is a screw provided with the box use it. If not, you must use self-tapping screws, never sheet metal screws, per NEC. Screws must be colored green. Home Depot carrries little bubble packs of green-annodized self tappers specifically for this. I used to buy plain bulk self-tapping screws and color them with a permanent Sharpie marker.

#14 wire is for 15 amp circuits (breaker or fuse controlling that circuit is 15 amps. You can exceed #14 and use #12 if you desire. If a 20 amp circuit, use #12, as #14 is forbidden anywhere on a 20 amp circuit.

Hope that helps.

Juice
 
  #4  
Old 12-21-04, 12:50 PM
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Frankly I think it's overkill to go with a separate grounding conductor, but it does in principle make it more reliable.
I have yet to see such an installation however.
 
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Old 12-21-04, 01:04 PM
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Most of the fittings/locknuts used for EMT on the market are made of zinc {hence no rust}.As long as the fittings are tight {setscrew & compression}at every point along the run it is safe. As was posted dont forget to use ground tails from each receptacle to the back of the box.To speed installation some come prepackaged with crimp rings,screws even wirenuts connected to 1 end of the lead.
 
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Old 12-21-04, 02:42 PM
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Once you have seen a burned up emt connector you will always run a ground. Often times a fault will arc and spark and melt metal long before a breaker trips. If the ground path to the breaker is compromosed enough it may never trip a breaker and the conduit will stay live until it finds a common ground. Might even be YOU!
No, it is not code to run one.
Ye, it is a better installation with one. Bare or green. Green is much more common.


Juice, just wondering how you bond your conduit using NM boxes. Do you use bonding bushings on every fitting?
 
  #7  
Old 12-22-04, 08:26 AM
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Thanks

Many thanks to everyone for the comprehensive advice on ground EMT.
Bill
 
  #8  
Old 12-22-04, 11:12 AM
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You can buy EMT connectors with a locknut that has a screw in it . Thread the locknut onto the connector and tighten the screw down. This ensures that the connector/locknut will not become loose and make a poor connection.
 
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Old 12-22-04, 11:48 AM
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Speedy Petey,

I do not bond my conduits when I use NM boxes because I run NM-B in such applications. When I do use EMT or RGS I use metallic boxes. But you've got me curious, what would your answer be if I used NM boxes with EMT? I would assume grounding bushings and a jumper through the box to bond the conduits.

Juice
 
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Old 12-22-04, 12:10 PM
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I think I misunderstood your post in this case. I thought you meany EMT with NM boxes.
If one did do this I guess you'd have to use one of these: <img src="http://www.o-zgedney.com/gif/FamDAInsulated.gif"> like you mentioned.
 
  #11  
Old 12-22-04, 12:20 PM
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Speedy,

That's the animal I was talking about.

BTW, I also am a Charles Schultz fan and a huge Chuck Jones fan. Big Tom & Jerry fan, too. But I suppose we should continue this discussion in the DIY Cartoon Forum...

Juice
 
  #12  
Old 12-22-04, 02:05 PM
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Originally Posted by JuiceHead
the DIY Cartoon Forum...
Sounds like a suggestion for the admin of this site!

The reason for my sig line is I am sick of people calling sports stars heros.
At least our heros help humanity. How else would we know that you can fill a rabbit hole full of dy-nee-mite and bring up a carrot gusher!
 
  #13  
Old 12-23-04, 07:30 AM
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Speedy,

The original Looney Tunes were packed with social commentary and satire. They were written as much for adults as for kids. They also parodied history as well as contemporary issues of the day. And through the animal characters they often addressed the human condition, ironically.

I, too, am wary of our society placing so much emphasis on sports heroes. In truth, I will not waste my time watching televised sports, but will gladly sit down with my kids for a couple hours to watch Bugs Bunny!

Oh, and I sure hope Wmozer's grounding thing works out.

Happy Christmas to all.

Juice
 
  #14  
Old 12-23-04, 11:19 AM
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I love loonie tones, the unedited versions. It bugs the heck out of me to sit down and watch one and it has been editted to modern day standards. I like to see Sylvester's tail get jammed into light socket. I don't care they think some idiot might copy it.
 
  #15  
Old 12-23-04, 12:06 PM
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Joed,

I also thrill to the unedited versions. There was this "anti-violence in kid shows" movement in the '80s when they removed exploding cigars blowing up in people's faces, cat tails jammed in electrical sockets and other things that MAIMED A DRAWING FOR PETE'S SAKE. Yes, give me the good old fashioned originals, violence and all, any day.

Hey, Wmozer, how's that grounding thing going?

Juice
 
  #16  
Old 12-23-04, 12:10 PM
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I mean we all grew up watching this stuff right? Has anyone tried any of those stunts? I know I haven't.


















Well, maybe one or two.
You know how hard it was for an 8 year old to get a hold of TNT???
 
  #17  
Old 12-23-04, 12:22 PM
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This thread has gone off topic. While it doesn't bother me any, site admin lets me know from time to time that, as moderator, I'm not supposed to let this go on.
 
  #18  
Old 12-23-04, 12:57 PM
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John Nelson,

While I appreciate the rules and the purpose of this site, perhaps occasionally we can have a little fun, so long as we don't go into politics, religion, or, god forbid, plumbing!!!

I appreciate your sense of responsibility. I also continued to refer to Wmozer's grounding issue, just to keep it loosely on topic.

Since Christmas lights are electrical, and so many people use them, by some far-flung association can I wish every body a happy holiday without drawing attention from the moderator?

And also, my wish for a very proseprous and electrically happy new year.

Juice
 
  #19  
Old 12-23-04, 01:24 PM
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Sorry, but all forms of fun are certainly forbidden! And wishing everyone happy holidays is a capital crime!! Consider yourself sternly reprimanded!!! Happy holidays to you too (knowing, of course, that the happiness of your holidays is directly proportional to the quality of your electrical grounding)!!!!
 
  #20  
Old 12-25-04, 07:09 PM
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FYI ........ Turner Classic Movies shows old toons the 1st saturday of every month {hopefully it will be every week soon}.I guess Juice,Speedy,Joe & myself have all been naughty.....no presents next year.Happy Holidays everybody
 
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