Sanity check- EGC required for feeders?

[iceworm]

All of the outfits I have done work for (major Industrial) specify a green wire egc in each conduit.. If there is flex, they spec a green wire external jumper.

I agree. Conduits do crack (at the fittings) and a flex is not much of an egc.

One issue I have run into at an older mill was with deteriorating conduits. The mill was a cadilac job when it was new. But no green wire EGC in the MCC feeders. Fast Forward 25 years. MCCs would develop an arcing ground fault, but with a compromised conduit EGC path, the current would not build quickly. The ground fault would burn away for several cycles until it went phase to phase - then it would trip quickly. In the meantime the faulted MCC was a real mess. No way was the mill ever going to rip out all the major electrical and rebuild.

I call GE and tell them I've got a slug of 1960s vintage, 600A, AK-25s . Do they have a retro fit trip unit that will monitor GF?

"Oh yeah. We got a Micro-Versa-Diga-Flux-fixall" trip unit replacement kit. We developed it for all the old mills that didn't pull a green wire ground. Arcing ground faults are burning up the MCCs that are not trippng quickly on GF and are burning up the MCCs before the phase to phase kicks in."

Ahhhh. Budget price, lead time, please.

So, I like a green wire ground and so do my customers. Is it better than a good conduit - No but they feel better seeing a fat wire in the lug in the connection boxes.

And most are going with MC-HL now, so this is getting to be a moot issue. But it is still in their specs - if conduit, then green wire.

ice

 

[iceworm]

...I guess I can pull a green so I can brag about how great of a guy I am, but I'm humble and a bit of a spendthrift so I don't.

For me, it wouldn't be a case of bragging rights.

If the specs say to pull a gwg - My recomendation would be to pull a green wire ground.

If the specs don't say, then don't.

I'm not a fan of giving away money. I am a fan of meeting spec.

ice

 

[ActionDave]

Agreed, you can always design above the Code requirements. But it sounds like some/many people think that using metal conduit as the EGC is actually better than a wire EGC.

It is. And we haven't even gotten into a discussion about all those green wires popping out of a wire nut that was not made up correctly.

That is the discussion that I am interested in hearing the pros/cons about. I would hope that the EC community could come to a consensus about the preferred method. Then each EC can have a discussion with the client about whether they want to pay for it or just meet Code.

You won't ever get a consensus. The discussion is never about what really works, it is always about what feels right/best or what one was taught when breaking in to the trade.

 

[ActionDave]

For me, it wouldn't be a case of bragging rights.

If the specs say to pull a gwg - My recomendation would be to pull a green wire ground.

If the specs don't say, then don't.

I'm not a fan of giving away money. I am a fan of meeting spec.

ice

Specs that are reasonable and specs that are insane and everything in between don't matter to me a bit when I'm on the clock.

 

[iceworm]

Specs that are reasonable and specs that are insane and everything in between don't matter to me a bit when I'm on the clock.

I'm with you there - except I do draw the line on No Felonies and no Death Traps

 

[iwire]

The metal conduit should be bonded at both ends anyway, even if you run a separate insulated EGC. It's not an 'either-or'. It's a question of whether or not you are able to sleep at night with having only the integrity of the fittings guaranteeing you a fault return path.

Personally, I'll include the insulated EGC's as added insurance every day of the week.

Why don't you loose sleep about the intrigity of the wire EGC connections?

EGC splices are the ones i find to be made poorly.

 

[Pharon]

Why don't you loose sleep about the intrigity of the wire EGC connections?

EGC splices are the ones i find to be made poorly.

I worry about those, too (as for actually losing sleep, it was just a figure of speech).

I realize this is MH Forum and people argue for 200 posts about what time of day it is, but I don't see why this is such a big deal.

We're not arguing the pros and cons of PVC/EGC vs. EMT/no EGC. It's EMT/EGC vs. EMT/no EGC.

Aren't two separate and distinct ground paths always better than just one?

I don't have the luxury of installing and walking away. I'm a facilities guy, and I have to live with this stuff forever. Iceworm's example above is a perfect argument why separate EGCs should always be run in a conduit. Because this stuff needs to last decades.

 

[paul]

Which part of my explanation was confusing to you?

I am not confused. I asked why to your explanation of bonding both ends of the conduit. The only guarantee this gives me is that the connectors are bonded.

 

[Pharon]

I am not confused. I asked why to your explanation of bonding both ends of the conduit. The only guarantee this gives me is that the connectors are bonded.

I'm still not sure what you're asking me about. But from the several posts I've made in this thread, my position on this topic should be clear by now.

 

[iwire]

I worry about those, too (as for actually losing sleep, it was just a figure of speech).

I realize this is MH Forum and people argue for 200 posts about what time of day it is, but I don't see why this is such a big deal.

We're not arguing the pros and cons of PVC/EGC vs. EMT/no EGC. It's EMT/EGC vs. EMT/no EGC.

Not arguing just asking questions. I would guess that at least 80% of the time I run a wire EGC in metal raceways, but that is mostly due to customer specifications.

Aren't two separate and distinct ground paths always better than just one?

No, not if you are the one paying the costs.

I ran a design build job where we installed a 3000 amp service and a 1,200 amp feeder from it. When it came time to run the 250'+ feeder I chose 3 sets of 600 copper in EMT. I chose not to run a wire EGC and used the EMT as the EGC. This saved me about 750' of copper and allowed me to run 3" vs 3.5" or 4". There is no doubt at all this EMT provided more than enough grounding capacity.

I don't have the luxury of installing and walking away. I'm a facilities guy, and I have to live with this stuff forever.

which also explains why installation costs don't seem to enter into your thoughts.

Iceworm's example above is a perfect argument why separate EGCs should always be run in a conduit. Because this stuff needs to last decades.

Underground we run PVC so that is not an issue, EMT run in a building will last as long as the building. If it is pulling out of fittings I have to question if it was installed to code to begin with.


For myself I try not to do things just out of habit, I really try to look at each job on its own merits and decide how to install based on that.

I will say this, I lose much more sleep worrying about wire EGCs to site poles than I do about EMT being as EGCs for other items. I do a lot of site light work and I have this fear of an innocent person getting a 277 volt blast off a light pole that has a failed EGC and a fault to ground. ... That really does worry me as I find bad wiring in these poles often.

 

[Pharon]

No, not if you are the one paying the costs.

Just because I'm a facilities guy doesn't mean I don't pay. I have my own capital budgets, and I have to pick and choose what gets installed in line with the funding I get. But I get paid to prioritize, and to me this is a priority.

I ran a design build job where we installed a 3000 amp service and a 1,200 amp feeder from it. When it came time to run the 250'+ feeder I chose 3 sets of 600 copper in EMT. I chose not to run a wire EGC and used the EMT as the EGC. This saved me about 750' of copper and allowed me to run 3" vs 3.5" or 4". There is no doubt at all this EMT provided more than enough grounding capacity.

So on design/build, there's no engineering specs? You just provide a lump sum for electrical and the owner has no say in what's important, as long as it meets minimum Code?

Underground we run PVC so that is not an issue, EMT run in a building will last as long as the building. If it is pulling out of fittings I have to question if it was installed to code to begin with.

Even the most solidly built system can develop a loose fitting, given enough time. Earthquakes, new work being installed around existing equipment, accidental forklift damage, etc.

I will say this, I lose much more sleep worrying about wire EGCs to site poles than I do about EMT being as EGCs for other items. I do a lot of site light work and I have this fear of an innocent person getting a 277 volt blast off a light pole that has a failed EGC and a fault to ground. ... That really does worry me as I find bad wiring in these poles often.

Yeah, I don't blame you there.

 

[kwired]

So on design/build, there's no engineering specs? You just provide a lump sum for electrical and the owner has no say in what's important, as long as it meets minimum Code?

Many customers have no clue of what to specify on such a topic, they will have preferences on appearance of luminaires and other things but the technical items they trust that the design/builder knows what they are doing.

 

[paul]

I'm still not sure what you're asking me about. But from the several posts I've made in this thread, my position on this topic should be clear by now.

As I mentioned before, the only real guarantee that I get is that my connector is solidly bonded. I get the exact same thing from a locknut or a grounding locknut at a fraction of the cost.

For instance, I just did a take-off on a job. It's upgrading a UPS for a data center. They are running (4) 3-1/2" EMT runs and want grounding bushings. I have a total of 8.. At $23 each that runs $184. Now the NECA book says it takes 1.2 hours of labor each in the normal column (this assumes everything is off and easy to get to). So I have 12.8 hours of labor added into the job. Let's figure low at $90/hour for the job cost on labor, van costs and other misc., I won't get into overhead and profit. That's $1152. Add to that the $184 and I'm up to $1336 in extra cost just to put bushings on the end of 4 runs of 3-1/2", when a locknut would do the exact same thing. If I add in the 3" and 2" runs, it's $160 more in parts and another 17 hours of labor that is put into the bid. Now I'm up to $3025 dollars to put bonding bushings on the conduits. That's not even getting into the EGC wire costs, because they love them in data centers. It's up around $8,000.

The price adds up pretty quick. But hey, what's a few thousand extra dollars on a public works project.

 

[Pharon]

As I mentioned before, the only real guarantee that I get is that my connector is solidly bonded. I get the exact same thing from a locknut or a grounding locknut at a fraction of the cost.

I don't disagree. But it sounds like your beef is with the NEC 250 Code Committee on that one.

The price adds up pretty quick. But hey, what's a few thousand extra dollars on a public works project.

I guess it depends on how important it is to you that future ground faults have an adequate low-impedance path back to source to clear themselves. Murphy's Law and all. Accidental shock deaths? Multi-million dollar equipment failures? What's that liability cost? Nothing, to the installing electrician -- as long as it meets Code. But what about the cost to the owner?

An ounce of prevention is worth a pound of cure.

 

[iwire]

Just because I'm a facilities guy doesn't mean I don't pay. I have my own capital budgets, and I have to pick and choose what gets installed in line with the funding I get. But I get paid to prioritize, and to me this is a priority.

We can agree to disagree, I see no real benefit in a wire EGC with feeder ran in a metal raceway in a dry location.

So on design/build, there's no engineering specs? You just provide a lump sum for electrical and the owner has no say in what's important, as long as it meets minimum Code?

It depends what they want. This customer does not have in house staff to write specs. They where being told by a conveyor company that 480 volt service would make much more sense. So the company I work for gave them a price to do just that. They had no interest in how we did it, they were in the home food delivery business not the construction business. We actually worked more like a GC than an EC.

My project manager handed me an 11.5"x8" sheet of paper with a hand drawn one line of what I was to do. There was a new pad mount, new switchgear, a 1000 kva dry transformer to re-feed the existing 208 service, a couple of 400 amp 480 volt feeders and a 1,200 amp 480 volt feeder. The paper only had breaker sizes, it was up me to fill in the blanks with wire, pipe etc. Certainly some of it was code minimum. That does not make it 'bad' or unprofessional.

Even the most solidly built system can develop a loose fitting, given enough time. Earthquakes, new work being installed around existing equipment, accidental forklift damage, etc.

Exactly, even with a wire EGC stuff can happen.