Why is SER ground so large

Status
Not open for further replies.
Tulsa Electrician said:
I would think this is two different in items.
480.40 grounding of panle boards.
Click to expand...
I see I used the incorrect code reference. 408.40 is the one I wanted to state.
Sorry for that.

It says in part " Where the panel board is used with nonmetallic raceway or cable or where separate equipment grounding conductors are provided, a terminal bar for the equipment grounding conductors shall be secured inside the cabinet. The terminal bar shall be bonded to the cabinet and panel board frame, if of metal; other wise it shall be connected to the equipment grounding conductor that is run with conductors feeding the panel board."

If I'm understanding correctly this requires a bar. This bar must be bonded to the enclosure if metal.

Then the attachment of this bar must meet bonding requirements.

So if a terminal bar not a lug is used I do see where it can be bolted as long as it is installed according.
250.4 (A) (5)
250.12
250.148 ( metal boxes (C))

As far as the bar goes it can be several configurations.
For this case a load center it would be the most common available from the mfg of that load center.
Then we have other types that lugs can be attached to however still a bar. Case in point a grounding buss bar which is bolted to the enclosure inside switch gear etc.



So based on that is why I say I would not do that. I believe A single lug should not be attached to the back of the can because there is not a large enough hole on equipment grounding terminal bar. Instead use the correct one made for the equipment and the equipment grounding bar if a larger conductor is required. In this case an add a lug or change the bar out with a one that has a larger lug on it.

I can personally say I have seen this a lug added to back of a can and in most cases after the wire had been added is was loose and not tight or more than one wire was under the lug. Makes for a poor installation.

I would also say how would you ever tighten it back up using the bolt and nut if you can not get to the bolt head after panel installation. If this load center in a wall. A loose lug is not a low impedance path. A loose nut and bolt does not have two threads in contact with the enclosure. However it does have a nut.
 
EeeeVeee said:
The way I see it, if someone is so concerned about this that they would pull an extra conductor, then they are the same type of person who would be concerned with installing the raceway properly. So there will be no issue.
Click to expand...

That's pretty much the way I see it. I always say if you're not confident in your conduit workmanship, you should probably reevaluate your career choice. If you aren't confident in your guys' workmanship, you should train them better. And good and proper conduit workmanship is always important and whether there is an EGC or not should not be a part of how it is done.

Finally I just think there is an overall excessive obsession with grounding and bonding. Sure bonding back to the source is an important component of solidly grounded electrical system that improves safety, but I don't think it's importance is commensurate with all the OCD that goes on over it. Let's go through the steps of what would have to happen to have a bad outcome from a raceway used as an EGC:

1. A fault actually has to happen
2. That fault has to not clear because of some major problem with the raceway.
3. For a fair comparison, If a wire EGC HAD BEEN installed, that would have cleared the fault, which is certainly not a given.
4. Whatever damage or problem with the raceway goes unnoticed and unresolved.
5. A fire has to actually start or someone actually has to get shocked.
6. If someone gets shocked, that actually results in an injury or death.

How come no one installs redundant ocpds or gfcis?
 
electrofelon said:
That's pretty much the way I see it. I always say if you're not confident in your conduit workmanship, you should probably reevaluate your career choice. If you aren't confident in your guys' workmanship, you should train them better. And good and proper conduit workmanship is always important and whether there is an EGC or not should not be a part of how it is done.

Finally I just think there is an overall excessive obsession with grounding and bonding. Sure bonding back to the source is an important component of solidly grounded electrical system that improves safety, but I don't think it's importance is commensurate with all the OCD that goes on over it. Let's go through the steps of what would have to happen to have a bad outcome from a raceway used as an EGC:

1. A fault actually has to happen
2. That fault has to not clear because of some major problem with the raceway.
3. For a fair comparison, If a wire EGC HAD BEEN installed, that would have cleared the fault, which is certainly not a given.
4. Whatever damage or problem with the raceway goes unnoticed and unresolved.
5. A fire has to actually start or someone actually has to get shocked.
6. If someone gets shocked, that actually results in an injury or death.

How come no one installs redundant ocpds or gfcis?
Click to expand...
If you are a couple man shop, that’s reasonable to do, but if you have several hundred employees, that’s a little harder. It’s not that they don’t know better, it’s just people are extremely lazy nowadays. When I fist started the trade, we would have maybe one slacker on a crew of 10, now you have 6-7 slackers on a crew of 10. Most on their phones talking to their girlfriends or baby momma’s half the day or more.
 
jaggedben said:
Some of you have clearly never had to tighten raintight EMT couplers from the top of a 32ft extension ladder. Wire EGCs for sure have their place.
Click to expand...
And that right there is my second problem with the members of the Cult of the Green Wire. Members of the cult are far more likely to settle for poor workmanship because, "Hey, it's got a green wire, so if it comes apart not such a big deal. We tried and came up short but we are spending more money on wire so that makes up for it".
 
jaggedben said:
Some of you have clearly never had to tighten raintight EMT couplers from the top of a 32ft extension ladder. Wire EGCs for sure have their place.
Click to expand...
This goes back to my point from earlier. If someone is so concerned about grounding being perfect that they will throw copper wire in the garbage by running a copper EGC, then they are the same type of person who would move their ladder to a better location (or get a new ladder, bucket truck, etc.) so that he can properly tighten the fittings on the raceway he is building.
 
EeeeVeee said:
This goes back to my point from earlier. If someone is so concerned about grounding being perfect that they will throw copper wire in the garbage by running a copper EGC, then they are the same type of person who would move their ladder to a better location (or get a new ladder, bucket truck, etc.) so that he can properly tighten the fittings on the raceway he is building.
Click to expand...
You clearly have never have never costed a 45ft ladder that you'll use twice. And I didn't say I didn't properly tighten the fittings.
 
jaggedben said:
You clearly have never have never costed a 45ft ladder that you'll use twice. And I didn't say I didn't properly tighten the fittings.
Click to expand...
In my 25 years I have done countless things that required a lot of work, money, and time just to do something that someone would consider “small“, for no other reason than because it’s the right way to do it.

I maintain what I said, if someone is going to go to the excessive lengths of running a redundant EGC, then they are the same type of person who is going to do whatever is necessary to properly build a raceway, which cancels out the need for the redundant EGC.
 
EeeeVeee said:
I maintain what I said, if someone is going to go to the excessive lengths of running a redundant EGC, then they are the same type of person who is going to do whatever is necessary to properly build a raceway, which cancels out the need for the redundant EGC.
Click to expand...
No they are going to run the wire EGC because the boss who can't there all the time looking over their shoulder told them to. Because the boss finds it a lot less time consuming to inspect the bonding in the j-boxes (perhaps by photo) than checking every coupler and connector, even while still telling people to do the latter. And because the boss knows that hiring the 'type of person' you're talking about isn't something one can do in today's labor environment just because the boss wants to. And because the boss considers that it might be a good thing having redudancy that exceeds code requirements to ensure saftey, while doing one's best to train, hire, and fire to get a good crew of such people is a constant battle.

All of which doesn't mean the boss won't skip the green wire when he is there personally and sees that a conduit size can be reduced, or another circuit run in the same raceway, or just to save time and money.
 
That's it, I'm installing a second, redundant OCPD in every circuit now, it's just not worth the risk having just one and having it fail. Plus, the chances of someone installing the wrong size breaker or swapping it out with a higher one later is not insignificant. It will be a good selling point, that I go above and beyond code minimum and install a second redundant ocpd for safety.
 
electrofelon said:
That's it, I'm installing a second, redundant OCPD in every circuit now, it's just not worth the risk having just one and having it fail. Plus, the chances of someone installing the wrong size breaker or swapping it out with a higher one later is not insignificant. It will be a good selling point, that I go above and beyond code minimum and install a second redundant ocpd for safety.
Click to expand...
I’m not sure if that’s going to help though. Without exaggerating, there has been countless times when I was troubleshooting an issue in a house and I found that the terminal on a breaker or the neutral bar was not tightened down. I’m talking it was completely open, no one ever tightened it when they put the wire in. The wire was making enough contact for the circuit to work but after enough current was drawn it would heat up and cause issues.

The only way to avoid this is to have every circuit fed from a second panel in some type of European loop design. This way if they forget to tighten one terminal they’ll be sure to tighten the other.
 
Some of you all have never done much service work, and/or have been in a limited number of environments and it shows. Lots of conduit gets installed on non-conductive surfaces. I've walked into tons and tons of boxes with loose lock nuts over the years. The argument can be made that "if it was properly installed it wouldn't be an issue" - but the fact of the matter is that in practice it isn't getting properly installed, or it's being field modified after initial installation in such a way that can potentially yield a weak EGC.

So, to counter this, a wire-type EGC is specified. That's just the way it is.
 
sparkie1 said:
Some of you all have never done much service work, and/or have been in a limited number of environments and it shows. Lots of conduit gets installed on non-conductive surfaces. I've walked into tons and tons of boxes with loose lock nuts over the years. The argument can be made that "if it was properly installed it wouldn't be an issue" - but the fact of the matter is that in practice it isn't getting properly installed, or it's being field modified after initial installation in such a way that can potentially yield a weak EGC.

So, to counter this, a wire-type EGC is specified. That's just the way it is.
Click to expand...
A loose locknut or setscrew is very likely not going to be an issue. Why does everything everyone think it's like the end of the world? It's going to be totally fine, chill out. Again, fascinating how the wire nuts and ground screws and ground lugs are always for some reason going to be properly made up.
 
electrofelon said:
A loose locknut or setscrew is very likely not going to be an issue. Why does everything everyone think it's like the end of the world? It's going to be totally fine, chill out. Again, fascinating how the wire nuts and ground screws and ground lugs are always for some reason going to be properly made up.
Click to expand...
Because your lock nuts are what hold the pipe tight to the box. Finding a poor ground makeup is just not as common as finding a loose locknut. You know, that whole part about how conduit gets ran on non-conductive surfaces all the time. It's an easy thing to forget.
 
We will just have to agree to disagree. That being said, job specs tend to agree with me.
 
electrofelon said:
I am not denying the reach of the cult of the green wire is very deep. By the way most people who write jobs specs have never installed any of this stuff and don't know poop from apple butter.
Click to expand...
Well, they know enough to know that conduit can easily come apart in the field.
 
electrofelon said:
Not in my experience. I see so many bad wirenut bundles, I trust the pipe more. A fault is still going to clear just fine ( if one happens at all) even with a few loose locknut or two, it's going to be fine. There is other more important stuff to worry about.
Click to expand...
I trust the rack install more than the locknut. Those have gravity helping maintain ground continuity.
 
Status
Not open for further replies.
Top