paul
Senior Member
- Location
- Snohomish, WA
I agree, the NEC shouldn't require a ground wire in EMT, they should ban EMT and require RGS or IMC with threaded connections instead. 
EMT as grounding
- Thread starter Eddy Current
- Start date
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Jim W in Tampa
Senior Member
- Location
- Tampa Florida
I agree, the NEC shouldn't require a ground wire in EMT, they should ban EMT and require RGS or IMC with threaded connections instead.
NEC does not require a ground wire so who are you agreeing with ?
weressl
Esteemed Member
On new installation and under laboratory conditions that may be true. Add a little corrosion, moisture to build up resistance across the couplings and connections and that will no longer be true.
I agree, the NEC shouldn't require a ground wire in EMT, they should ban EMT and require RGS or IMC with threaded connections instead.
Shhhhh!!!!
Don't give Chicago any ideas
On occaision.
Allowing exposed SE cable for service conductors comes to mind.
I wouldn't say that the EGC/EMT issue is boderline dangerous. I'm just saying it aint a bad idea. IMO, the conduit is there to protect the wires. Pulling a full set isn't a big deal. Maybe because it's standard practice/required here and I've been doing it for decades?
Also, IMO, the problem with EMT connections are more wear and tear than simply corrosion. Some conduit systems will remain 100% intact for 50-100 years. Others are more exposed to a ton of rework/remodel/abuse and get pulled apart. No matter how much you tighten conectors, some HVAC guy can pull them apart to make room for his ductwork.
renosteinke
Senior Member
- Location
- NE Arkansas
Borderline dangerous .... hmm, isn't that the very definition of the purpose of the NEC, as outlined in Article 90? The PRACTICAL safeguarding of electricity.
I've witnessed the lab tests, and even a really poor, nearly falling apart run of pipe can carry an amazing amount of fault current. IMO, those who automatically want to 'improve' things with a green wire are the types who would wear both a belt and suspenders. Just in case.
Yet, I have plenty of pictures of situations where the EMT has failed. In every case, the cause was either a) choosing EMT, or the routing, was inappropriate, or b) the pipe was damaged by after-the-fact activities. Let's look at a few:
1) EMT on a wall separates ater being rammed multiple times by stock-handlers as they make their turns. Maybe the pipe should have been run a bit higher up the wall?;
2) EMT separates when a landlord hires a crew to cover his rotting wood siding with stucco. The crew prys the pipe from it's anchors to get the plaster under the pipes;
3) EMT run on the face of a curb separates after years of being used as a step and being struck by dolly wheels or snow plows;
4) Rooftop EMT separates as the roofers replace the roof; and,
5) EMT run underground rusts completely apart at the 6" level.
OTOH, there is no law that says you're forbidden to 'exceed' code. At some point, your professional judgement can tell you that it's a good idea to add a green wire. When you just KNOW the pipe is going to be disturbed - like across a roof - adding that green wire just makes sense. As does, perhaps, using better connectors, more supports, and shanging methods as the exposure requires.
Article 110 requires our methods to be appropriate to the application. Sure, maybe the code says you can use steel outdoors .... but I interpret signs of rust and damage as evidence that the installation does not comply with Article 110's requirements that the wires be mechanically protected and that the materials be corrosion resistant.
I've witnessed the lab tests, and even a really poor, nearly falling apart run of pipe can carry an amazing amount of fault current. IMO, those who automatically want to 'improve' things with a green wire are the types who would wear both a belt and suspenders. Just in case.
Yet, I have plenty of pictures of situations where the EMT has failed. In every case, the cause was either a) choosing EMT, or the routing, was inappropriate, or b) the pipe was damaged by after-the-fact activities. Let's look at a few:
1) EMT on a wall separates ater being rammed multiple times by stock-handlers as they make their turns. Maybe the pipe should have been run a bit higher up the wall?;
2) EMT separates when a landlord hires a crew to cover his rotting wood siding with stucco. The crew prys the pipe from it's anchors to get the plaster under the pipes;
3) EMT run on the face of a curb separates after years of being used as a step and being struck by dolly wheels or snow plows;
4) Rooftop EMT separates as the roofers replace the roof; and,
5) EMT run underground rusts completely apart at the 6" level.
OTOH, there is no law that says you're forbidden to 'exceed' code. At some point, your professional judgement can tell you that it's a good idea to add a green wire. When you just KNOW the pipe is going to be disturbed - like across a roof - adding that green wire just makes sense. As does, perhaps, using better connectors, more supports, and shanging methods as the exposure requires.
Article 110 requires our methods to be appropriate to the application. Sure, maybe the code says you can use steel outdoors .... but I interpret signs of rust and damage as evidence that the installation does not comply with Article 110's requirements that the wires be mechanically protected and that the materials be corrosion resistant.
peter d
Senior Member
- Location
- New England
Allowing exposed SE cable for service conductors comes to mind.
You should qualify your comment by saying that you have no firsthand experience with SE cable and that's only your opinion.
Those of us who do have first hand experience with SE cable and work in areas where it's common know that it's a safe wiring method used in countless installations for decades without trouble.
Fail #1. :roll:
1. I have plenty of first hand experience with SE cable. It's a fine product when concealed and protected via OCPD's
2. Everything I say is only my opinion. It's is stupid to expect me to preface everything I say with a disclaimer.
3. I've also never installed bare split bolt connectors to extend wires in a panel but I KNOW it aint safe.
4. I could go on forever but, if you don't understand my point, you never will.
Fail #2 :roll:
There are a lot of electrical installations that have been in use for decades. Just because it's common doesn't make it safe. Just because you use this method doesn't mean you know anything. Yours is simply another opinion.
Unfused wiring needs to be treated with much more care than fused wire. It's comon sense. More danger needs more protection. I can say it a million different ways that all make sense. The only thing you have is "We do it that way and it's fine".
It's a third world installation.
My opinion of course^
- Location
- Massachusetts
1. I have plenty of first hand experience with SE cable. It's a fine product when concealed and protected via OCPD's
2. Everything I say is only my opinion. It's is stupid to expect me to preface everything I say with a disclaimer.
3. I've also never installed bare split bolt connectors to extend wires in a panel but I KNOW it aint safe.
4. I could go on forever but, if you don't understand my point, you never will.
This from the guy that says the code should use commonsense.
What would be the commonsense of banning a method that has a huge history of safe installations?
You want to ban a method because you are sure it is bad but history proves you are mistaken.
Fear is not a reason for a code rule.
You are right, just the fact it is common does not make it safe.
But the fact that is very common and has not left a trail of burned properties and dead homeowners does say a lot.
Show some proof it causes more fires or more injuries than you might have a reason to want it restricted.
Again if it was just me and Pete using it you would have a point, but I can drive past 100s of SE services in my own town never mind my county, or state, or region.
If SE was as dangerous as you seem to think it is electricians in this area would know about it because we would be replacing them.
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To me, common sense says to protect unfused condutors.
How many people have been hurt by contacting exposed SE service conductors? You don't have any more facts than I do. You are assuming that it is extremely rare.
Fear is the only reason for code rule.
Woo Hoo!!
I have the same documents as you do. None.
Try not to take it personally. The bottom line is that you are allowed by your local AHJ to use this installation. My opinion doesn't matter. And, I will never be making any code decisions or official suggestions so you have nothing to worry about.
readydave8
re member
- Location
- Clarkesville, Georgia
- Occupation
- electrician
yeah but mine was dumber
sd4524
Senior Member
- Location
- Southern California
So should we start selling maintenance contracts where we visit buildings once a year or every other year and tighten/ torque all emt setscrews? Same for compression couplings and connectors. Seams with the right marketing efforts that it could lead to scheduled work and then profitable repairs. Any industrial/ commercial companies ever try this? People can get scared into anything
weressl
Esteemed Member
In real life corrosion of copper wires usually only occurs when aggressive chemicals are present. The copper connectors are designed to be flexible and to maintain the pressure under the thermal cycling. The steel and iron used for raceways are attacked by atmospheric moisture.
This comes from the person that uses sheet metal screws to ground old metal boxes with no threaded holes, interesting.
For the record I think the "wire EGC in conduit" amendment is great but at the same time I hate it, and break it from time to time (oh no :roll
.
- Location
- Massachusetts
And you know this from all your years out in the field servicing electrical installations. ...:grin:
I find corroded copper conductors in any location that they get wet, particularly under the steel spring of a wirenut.
Can you show me one of these copper connectors because I do not run into them in the wild. :roll:
And these extreme conditions exist inside all bldgs? Hmmmm, maybe someone should let the authors of NFPA 99 and CMP #15 know this, they could then change 517.13 and especially 517.13(B) Exception No.2.
Roger
Granted, they aren't machine screws but they aren't sheet metal screws. The box says "self tapping screws". I checked
And, the installation is 100% secure. If you want to meet for lunch in Central Phoenix, we can stop by, pull it apart and tug on it. For a real adventure we can even short it out .
And, the installation is 100% secure. If you want to meet for lunch in Central Phoenix, we can stop by, pull it apart and tug on it. For a real adventure we can even short it out .
I was just being me, I know it works just fine cause I do it too
Oh and I had the help accidentally nick a hot wire in a box I grounded with a self tapper and it tripped the breaker so I am now totally good with it.
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