What Would You Do?

[liquidtite]

I was thinking that 250.32(B)(1) Exception might allow the bonding to the grounded conductor. I would not consider the rusted rigid to be a continuous metallic path.

check for continuity with your tester.if its not continuous pull a new gec

 

[kwired]

I am going to get on my high horse once and then bow out of this discussion. There are so many things that can happen. What if the neutral opens up at the main service, You now have 240 volts on the conduit, panel shell etc. trying to find a path. If the conduit is as bad as you think this would probably result in death! Regardless of how unlikely that is, it is really possible. When the neutral and ground are bonded at least a ground rod is driven, but that is sometimes not enough, which is likely why the code was changed in the first place. I have not been here as long as you, but if you are looking for a place to validate substandard work, this is probably not the best place. Tell the customer to install a new conduit run or walk away from it. The greatest sin here would be someone trying to circumvent the code and getting someone else killed. That is a VERY REAL albeit unlikely result.

Voltage encountered on grounding system in the case of an open grounded supply conductor will not necessarily be 240 volts but can be well over 120. It all depends on what the loading conditions are. Perfectly balanced between the two lines will not have any voltage to ground but that is not likely to happen either, one situation that balance is more likely is no load on either side.

You are better off isolating the rigid pipe and bond the neutral to the can. You could also test the rigid to see if there is enough of it together that the impedance is not to high. Personally I would try and run a new run with PVC and 4 wires. If the conduit is that bad then the wires are probable sitting in the soil in places. I wonder whether the insulation is rated for wet location.

If it was underground and done properly it should be rated for wet location, but may not be rated for direct burial.

check for continuity with your tester.if its not continuous pull a new gec

Continuity check will not tell you how much fault current it can carry without burning the circuit to an open condition.

 

[liquidtite]

what about puting a new groundrod in at the location of the subpanel even if you have to jackhammer through the slab

 

[kwired]

what about puting a new groundrod in at the location of the subpanel even if you have to jackhammer through the slab

At a separate building there needs to be grounding electrode system and if initially done correctly there is already a GES there. GES is not a substitute for an equipment grounding conductor, it is for dissipation of transients.

 

[Dennis Alwon]

what about puting a new groundrod in at the location of the subpanel even if you have to jackhammer through the slab

Required yes but it will not be a substitute for an egc. No way a ground rod will clear a fault.

 

[liquidtite]

dosnt the egc become a grounding conductor because its bonded to the grounding bus bar witch the gec is terminated to.So say if theres a groundfault on a branchcircuit from the mdp wouldnt the fault travel through the egc of that circuit and find its way to eatrh through the gec?.I can see if there was no gec from the mainpanel to the sub and just a gec at the subpanel im shure it would not trip the ocp in the mdp if a fault did occur.I was just curious why the gec wouldnt carry a fault

 

[ActionDave]

...I was just curious why the gec wouldnt carry a fault

I would. Just not enough to be counted on to clear a fault.

 

[kwired]

dosnt the egc become a grounding conductor because its bonded to the grounding bus bar witch the gec is terminated to.So say if theres a groundfault on a branchcircuit from the mdp wouldnt the fault travel through the egc of that circuit and find its way to eatrh through the gec?.I can see if there was no gec from the mainpanel to the sub and just a gec at the subpanel im shure it would not trip the ocp in the mdp if a fault did occur.I was just curious why the gec wouldnt carry a fault

If ground rod has a resistance of 10Ω (which is considered good for a ground rod) and there is a fault on 120 volt ungrounded conductor how much current flows?

Only 12 amps.

Not going to be enough to open even a 15 amp overcurrent device. Guess what all becomes a higher voltage to earth in this situation?

Grounding electrodes are not intended to carry faults, they are intended to bleed off transients primarily from lightning, but also sometimes from POCO switching or other incidents that may send a surge down the lines. A fault is not trying to get back to ground it is trying to get back to the source - usually a transformer. Some fault current may find a way back to transformer via grounding electrodes and earth paths, but there is much less resistance through an intended conductor such as copper or aluminum.

 

[A/A Fuel GTX]

Getting back to the gist of this thread........I'm still wondering why a parallel path is fine for a service but not for a sub panel within the same structure? Not arguing, complaining or whining.........just wondering.

 

[petersonra]

Getting back to the gist of this thread........I'm still wondering why a parallel path is fine for a service but not for a sub panel within the same structure? Not arguing, complaining or whining.........just wondering.

There are all kinds of things allowed for services that are not allowed downstream. I am not sure that what you are sugegsting would be legal for a service either.

In any case, this is not a service, and it is not a seperate structure so you don't have a choice in the matter.

 

[A/A Fuel GTX]

I am not sure that what you are sugegsting would be legal for a service either.

The parallel path where the grounded conductor is bonded to the meter socket, a metallic raceway is run to the loadcenter/panelboard and the grounded conductor is once again bonded to the enclosure. Perfectly legal.