Steel structure used as a Equipment Grounding Conductor

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Under the NEC, in most if not all cases, no.

If you meant Grounding Electrode Conductor or extension thereof, the answer would be yes.
 
Do you use NEC where you are at? I see your location is Denmark. If not, the answer to your question may be different then it is for NEC applications.
 
No it is for the US market!
According to IEC 60364 it is legal to use steel structure as a ground conductor, for the return path in case of for a ground fault, it just need the same conductivity as defined copper conductor.

There for it is a big design change, for complying the NFPA 70...
 
Martin Bonde said:
No it is for the US market!
According to IEC 60364 it is legal to use steel structure as a ground conductor, for the return path in case of for a ground fault, it just need the same conductivity as defined copper conductor.

There for it is a big design change, for complying the NFPA 70...
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Solidly-joined metallic raceways, certain metal cable sheaths, and enclosures typically qualify as an EGC. Limitations typically apply to flexible metal raceways and sheaths.
 
I guess next question is are you talking steel structure of a building or steel structure of a listed piece of equipment that you may be making to ship to US.
 
Martin Bonde said:
No it is for the US market!
According to IEC 60364 it is legal to use steel structure as a ground conductor, for the return path in case of for a ground fault, it just need the same conductivity as defined copper conductor.

There for it is a big design change, for complying the NFPA 70...
Click to expand...

The US electrical code requires the EGC be run with the circuit conductors in almost all cases, so using something else like the structural steel would not be in compliance. It should not make all that much difference to a machine builder as the builder won't be the one running power to the machine anyway.

However, your profile says you are in the wind turbine industry, and that may change the answer to some extent, since the turbines might be considered part of a generating utility that operate under a different set of rules.

In any case, this does not seem like all that much of a design change to me. Just run an extra wire with the circuit conductors as an EGC.
 
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It will be steel structure of a listed piece of equipment (Wind turbine)! But due to the NFPA 70, do this make a difference if it is a building or some equipment? I'm not used to read the NFPA 70 :huh:
 
Martin Bonde said:
It will be steel structure of a listed piece of equipment (Wind turbine)! But due to the NFPA 70, do this make a difference if it is a building or some equipment? I'm not used to read the NFPA 70:huh:
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NEC doesn't apply to the components of a listed piece of equipment, you need to look at what the listing requirements call for. Wiring running to/from your piece of equipment likely will be required to have an equipment grounding conductor by the NEC though.
 
Added thoughts.

It is hard to comment on your question with any certainty as you have not provided anywhere near enough information about what your actual situation is to make an informed comment.

For instance, in most cases if these are small turbines that a typical homeowner might have installed in their backyard, they would come under a different set of rules than if it is part of a giant wind farm.

If it is in someone's backyard, there may be listing requirements that you need to be aware of beyond just meeting the requirements of the NEC.

Also, in general, what is inside of a manufactured piece of equipment may well have different requirements than the installation as a whole, which is what the NEC (NFPA70) covers. For instance, it is not all that unusual for a piece of equipment to use the structural steel of the equipment as part of an electrical enclosure that also forms part of the EGC. However, the circuit conductors would be inside of that enclosure and thus run with it, so it would effectively comply with the particular code requirement I mentioned.
 
petersonra said:
The US electrical code requires the EGC be run with the circuit conductors in almost all cases, so using something else like the structural steel would not be in compliance. It should not make all that much difference to a machine builder as the builder won't be the one running power to the machine anyway.

However, your profile says you are in the wind turbine industry, and that may change the answer to some extent, since the turbines might be considered part of a generating utility that operate under a different set of rules.

In any case, this does not seem like all that much of a design change to me. Just run an extra wire with the circuit conductors as an EGC.
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Thanks!
Can you tell me which set of rules I am going to use when talking about generating utilities?
 
Martin Bonde said:
It will be steel structure of a listed piece of equipment (Wind turbine)! But due to the NFPA 70, do this make a difference if it is a building or some equipment? I'm not used to read the NFPA 70 :huh:
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If it is a listed piece of equipment, the standard by which you build it will tell you what you are allowed to do. Generally speaking, I would expect that the listing standard would allow the steel to be part of an enclosure that could be part of the EGC path.
 
Martin Bonde said:
Thanks!
Can you tell me which set of rules I am going to use when talking about generating utilities?
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every state has different rules that electrical utilities in that state have to follow. another poster mentioned one that is common to most states. there are also some OSHA issues that you may have to accomodate.

to be honest, I doubt that anyone here is in the business of making wind turbines for the utility market. it is a highly specialized thing. it also seems unlikely to me that such a piece of equipment would be listed due to its nature.
 
As far as I know none of the wind turbines in my area have been installed or are owned by a utility.

Even if you can use a "remote" path as the fault clearing path (equipment grounding conductor), why would you want to? Where you have current flow on conductors that are separated from each other the impedance goes up. On high current circuits the increase in the impedance could move you along the trip curve so that you are not tripping in the magnetic or instantaneous. The longer it takes to clear the fault the more damage you have to the equipment.
 
don_resqcapt19 said:
As far as I know none of the wind turbines in my area have been installed or are owned by a utility.

Even if you can use a "remote" path as the fault clearing path (equipment grounding conductor), why would you want to? Where you have current flow on conductors that are separated from each other the impedance goes up. On high current circuits the increase in the impedance could move you along the trip curve so that you are not tripping in the magnetic or instantaneous. The longer it takes to clear the fault the more damage you have to the equipment.
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I agree, but with a wind turbine we could have a metal pole being used as a raceway for conductors - in that case I don't see an issue with using the pole as the EGC.
 
kwired said:
I agree, but with a wind turbine we could have a metal pole being used as a raceway for conductors - in that case I don't see an issue with using the pole as the EGC.
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On utility size turbines, I would want to see an EGC in each cable. The size of the support pole is big enough to create a large separation between the circuit conductors and the fault return path.
 
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