I'm used to working on "service supplied" and not generator supplied as sparkey874 has. I am clear on the need for a bond between neutral and equipment ground and in the situations I encounter this would be at the service panel. In his situation, would you bind at MDP or at the generator ??? (I understand the generator does have a main breaker)
Grounding vs Bonding issue.
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e57
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Call me salty but back in my day (USMC 1142 90-94) the NEC was not applicable to field installations. IMO certain political organizations are using it, and fatalities to their own political advantage to insert their personnel into lucrative positions....
But that said, 250.32 can provide guidance. That said, there have been recent changes to it... But may or may not be applicable to the install you have... Bottom line is if you have an equipment ground it will need to go to any rod at the separate structure, lacking any suitable equipment ground conductor would mean using the neutral bonded at the remote structure as a ground fault path so long as you are not creating a parallel path for neutral current. While this method is only as an exception to the current version of this code section, it is perfectly safe IMO.
As for this "metal braid" issue.... I assume your MDP is free standing next to a gen set, and this metal briad is a strain releif for the cable feeding it? This does not sound like a suitable grounding means to me, and IMO should be a 4-wire with ground cable, or neutral bonds as seperate structures would be... Otherwise this 'metal braid' is a second path for neutral current. And unsatisfactory...
But that said, 250.32 can provide guidance. That said, there have been recent changes to it... But may or may not be applicable to the install you have... Bottom line is if you have an equipment ground it will need to go to any rod at the separate structure, lacking any suitable equipment ground conductor would mean using the neutral bonded at the remote structure as a ground fault path so long as you are not creating a parallel path for neutral current. While this method is only as an exception to the current version of this code section, it is perfectly safe IMO.
As for this "metal braid" issue.... I assume your MDP is free standing next to a gen set, and this metal briad is a strain releif for the cable feeding it? This does not sound like a suitable grounding means to me, and IMO should be a 4-wire with ground cable, or neutral bonds as seperate structures would be... Otherwise this 'metal braid' is a second path for neutral current. And unsatisfactory...
e57
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This is the older version of the code, and may help you better understand it.
That's the problem, they can't. There is so much that goes into the contract side of the whole deal as well, which seems to be important than actually making everything safe.
The generators would be considered Seperatly Derived Systems, and yes you would bond at the generator. The big problem in Iraq/Afhganistan that I ran into is that they never ran a grounding conductor. You would have 3 phases and a neutral conductor. Basically, the distribution system would go; gen set to MDP, MDP to SDP, and SDP to end user. With only 3 phases and a neutral being ran to each panel, every panel needed to have a bond as well, so that fault current could get back to source.
I do understand that this is not the proper way to wire these installations. These are considered "temporary systems" by the powers that be, and they don't want to put more money into something that is "temporary". We can only inspect the contractors work, and make it is safe as we can with the limited resources.
In his situation, would you bind at MDP or at the generator ??? (I understand the generator does have a main breaker)
If a grounding conductor is ran from the gen set to the MDP, then you would bond at the gen set.
Exacately. The problem we saw was no grounding conductor being ran, just the steel braid being used as the grounding conductor. We did not allow the steel braid to be used as a grounding conductor. We would have the contactor disconnect the steel braid on one end, and then do the neutral bond at the remote structure or panel.
sparkey874
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Ok, I'm trying to get a plan fromulated so I get get 2 guy's working on it. In need to;
1) Ground and bond at the genset, now do I bond them together, the seperate set's because they both feed the MDP?
2) At the MDP I shoulodn't have to bond, just ground it to a rod
3) At the PP, I carry the ground from the MDP to the PP and can leave the ground rod alone because it's grounding the metal frame of the CHU, not the PP. How am I doing so far?
Thanks gent's for all your help.
1) Ground and bond at the genset, now do I bond them together, the seperate set's because they both feed the MDP?
2) At the MDP I shoulodn't have to bond, just ground it to a rod
3) At the PP, I carry the ground from the MDP to the PP and can leave the ground rod alone because it's grounding the metal frame of the CHU, not the PP. How am I doing so far?
Thanks gent's for all your help.
Connect a bonding jumper from your equipment ground (lug or bar) to your neutral bar . Size per 250.28 (250.66 normally) The bond should be there (at the gen set) IF you have a separated equipment ground and bond to MDP
Bond to all electrodes available & building frame, etc.
Forgot what "PP" is and did not catch in re-reading. IN summary, there is one neutral ground point, after that everything is bonded via your equipment grounding conductor. At separate buildings, you also add a grounding electrode connected to your equipment ground and assure all metal is bonded to that point also (water pipes, building steel, etc)
e57
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While you may not be familiar with this - you want this to act as a "service". It should be the most permanent part of the whole system.... Collectively - with this "service" (MDP) and the collection of generators on it, lets call it a single entity, a "generator farm" (As I would back when doing the same type of crap...) Think of this area seperately than one would for the whole sytem including everything else. FYI there has been previous debate about referring to your particular situation as a "SERVICE" as you have no untilty "serving" you - IMO you ARE the utility!
Also in code terminology you are using a number of "Seperately Derived Systems" to serve as the main source of power - again - IMO YOU ARE A UTILITY!
It's important for you to find out if there is a neutral/ground bond at the generator. Most of the military issue 60kw and above I worked on do not bond here - and that's OK.... All of the trailer mounted equipment with a generator on the same trailer will bond there - and that too is OK.... Just completely disconnect the unit - and ring it out/check continuity from the generator chassies to neutral at the lugs that would feed your MDP(Service)..... Once you know if there is a bond - act accordingly. You do not necessarily want a bond at each - because this is a second path for neutral current, depending on the grounding arrangement.
OR:
Here you should definately BOND the the neutral to ground, and to a permanent electrode/rods. Reason being - is that there will be times that you take one or more of the gen sets off line or remove them completely. (I Know I did A LOT!) You never want the system to be without a MBJ ('Main Bonding Jumper -neutral to ground bond)
If you mean a Power Panel in/on on the equipment/CHU you would also have an electrode there, and depending on if the thing is fed with an equipment grounding conductor - it either should, or should not have a neutral bond there as well.... These trailers or "CHU's" are "Seperate Structures" fed by "Feeders", and serve "Branch circuits" from the panels in/on them. See below:
Now if they do not have an EGC run with the circuit conductors it can be done like this - But - and very important in your particular situation - YOU CAN NOT BE ABLE TO TOUCH TWO STRUCTURES (CHU's) AT THE SAME TIME! THEY NEED TO HAVE SOME DISTANCE BETWEEN THEM!
Hope this helps.... Semper Fi
Mark Heller
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e57
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Additionally - I'm going to say the following - for your particular situation - the two following arangments are the safest for generator grounding/bonding and seperate structure feeder grounding - in your particular situation>>>>
EGC to each generator set - Not this "metal braid" you speak of - but if present grounded on one side only.
Or seperate electrodes - also without this 'metal braid you speak of as a conductor - but if present grounded on one side only.
EGC with the feeder - Not this "metal braid" you speak of, as it does not qualify as a grounding conductor in my personal and professional opinion. And does not expose the metal exterior of the structures as "current carrying". Since from experiance stuctures can be very close together....
EGC to each generator set - Not this "metal braid" you speak of - but if present grounded on one side only.
Or seperate electrodes - also without this 'metal braid you speak of as a conductor - but if present grounded on one side only.
EGC with the feeder - Not this "metal braid" you speak of, as it does not qualify as a grounding conductor in my personal and professional opinion. And does not expose the metal exterior of the structures as "current carrying". Since from experiance stuctures can be very close together....
Sparky874
Follow e57's drwaings/explanations, and you shouldn't have any problems. His drawings really show a good example of what I remember seeing over there. I also agree with him that the steel braid should not be used as EGC and should only be connected on one end.
Follow e57's drwaings/explanations, and you shouldn't have any problems. His drawings really show a good example of what I remember seeing over there. I also agree with him that the steel braid should not be used as EGC and should only be connected on one end.
sparkey874
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- Erie, PA in the Civilian work
Ok, first off, thank you all for your help. You have given me a lot of great info about this most confusing subject. Today one of the civilian electrical co's came in and is going to fix the grounding issues. We're up to our neck's in a huge project and the Command Sargent Major wanted to get it fixed faster than I get to it. LOL... I did a turn over with them and printed off the diagrams you sent. They said it was an easy fix. Hope they get it right! I'll be checking up on them before they finish I hope. Again, thank you for all your help. You guy's are great!
R/
CE2 Kennedy
R/
CE2 Kennedy
e57
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Really it's not a problem to help. AND FYI it has not been the first time we have answered questions on this very type of topic - in the very same places.... What you have is a number of situations that do not necessarily fit into the code book so to speak. (Semi-permanent generator fed - semi-permanent campus structures) Glad to help...
The biggest thing you need to do is stand up to the CSM, and tell him if he wants his project done safely and correctly, he needs to back off. Just do it tactifully. You are in one of the few jobs over there where you can (in polite terms) tell someone who out ranks you to back off. Especially with the TF SAFE stuff going on he can't push you too hard. If they make you do something unsafe or incorrect refuse to do the job, as long as you know you are in the right. Your command should have your back.
I am an E6, but at any given time I may have to brief anyone from a 1LT to a General. You can stop a job if it is unsafe, just be able to back yourself up.
e57
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It has been brought up at least twice a year on each of the forums I'm on since '02. Long before TS Safe (an article) - a knee jerk political reaction to shoddy contractor work, and some teary eyed public testimony - result = Lucritive contracts - more outside contractors inspecting work done by other contractors - I hope they are also not inspecting their own work.....
That said:
I have a PERSONAL BEEF and this is less political than it seems, I just want to focus on the TRADE aspect here - Outside contracting was never allowed in such politically sensitive, combat inflicted areas in any previous wars... Who was doing it? Seabees, (Like this guy.) Marine Corps Engineers (like myself formerly), and Army Corps of Engineers. Who does it when they need something done before an RFP can go out to some multi-national corporation - THEY DO! Yet, their training and materials budgets are drained for corporations and contractors to do the same at 5-10 times the cost, and now futher drained by "Inspectors" hired by some other corporation to ensure the work was done right.... Sorry it just makes me mad.
It is a disservice to all that serve, that 'contracting for profit' is taking away from the "bean and bullets" budgets in every branch of service. When that HUGE amount of money would be better spent on better training and more positions for the young people willing to serve in uniform.* Training that is uniform, and accepted by every BAT, UATC, and JATC. Because right now it is not... And that is a huge dis-service IMO. These guys joined to get a skill worth something. And perfect example is this and other continuing questions coming from service members who have had all their training knocked out from under them - stuck in a foriegn country - asking guys like us on internet forums on the other side of the world how to do bonding and grounding.... :roll: When it would be easier and cheaper to hire Mike Holt himself to show up at Court House Bay N.C. once every 3 months.... +/Or printing a code book for every electrician in the service. (Yes - something they do not have.) *Not trying to take away from what the contractors employees are doing there, but I'm sure you get paid a lot more than any E-4 does, at a cost to the branch services of an O-6 or >. And do so with the right tools and material at hand for the most part. (But apparently with very little over-sight, and lots of cut corners...)
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MXStar-keep in mind we at this forum are all about the NEC rules. If you system was installed per the scope of the NEC, then we can help. But if installed per some other foreign standard, then the rules are different, and how the grounding/bonding is done is different.
sparkey874
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- Erie, PA in the Civilian work
Tom,
I started this post. According to Task Force Safe we are all suppost to be following the NEC here in Iraq. We are suppost to be going back over the original work and bring it up to Code, especally in the wet CHU's and in the various sleeping quarters. I'm not really sure why were not using the european standard here instead of the american NEC. Do you know?
Thank you
I started this post. According to Task Force Safe we are all suppost to be following the NEC here in Iraq. We are suppost to be going back over the original work and bring it up to Code, especally in the wet CHU's and in the various sleeping quarters. I'm not really sure why were not using the european standard here instead of the american NEC. Do you know?
Thank you
I am not sure what this is about?
It has been brought up at least twice a year on each of the forums I'm on since '02. Long before TS Safe (an article) - a knee jerk political reaction to shoddy contractor work, and some teary eyed public testimony - result = Lucritive contracts - more outside contractors inspecting work done by other contractors - I hope they are also not inspecting their own work.....
That said:
I have a PERSONAL BEEF and this is less political than it seems, I just want to focus on the TRADE aspect here - Outside contracting was never allowed in such politically sensitive, combat inflicted areas in any previous wars... Who was doing it? Seabees, (Like this guy.) Marine Corps Engineers (like myself formerly), and Army Corps of Engineers. Who does it when they need something done before an RFP can go out to some multi-national corporation - THEY DO! Yet, their training and materials budgets are drained for corporations and contractors to do the same at 5-10 times the cost, and now futher drained by "Inspectors" hired by some other corporation to ensure the work was done right.... Sorry it just makes me mad.
*Not trying to take away from what the contractors employees are doing there, but I'm sure you get paid a lot more than any E-4 does, at a cost to the branch services of an O-6 or >. And do so with the right tools and material at hand for the most part. (But apparently with very little over-sight, and lots of cut corners...)
I agree with you, and I am a E6 in the Army. I don't like all the contractors over there either, because my job has turned into contract oversight rather than actually doing the work.
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