Is it a requirement or good idea to ground metal bleachers?

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bradmaggard

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We are wiring a new football stadium which utilizes metal bleachers. The engineer has not added any type of grounding or lightning protection to these bleachers. Is there any requirement for this and if not, is it a good idea to do so, or does it cause the potential for other hazards?
 
bradmaggard said:
We are wiring a new football stadium which utilizes metal bleachers. The engineer has not added any type of grounding or lightning protection to these bleachers. Is there any requirement for this and if not, is it a good idea to do so, or does it cause the potential for other hazards?
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JMNSHO.

What do you mean by grounding?

what do you mean by lightning protection? who cares if the bleachers are hurt by lightning? and there is no practical way to protect people sitting in them from lightning, even if you could protect the bleachers themselves.
 
petersonra said:
JMNSHO.

What do you mean by grounding?

what do you mean by lightning protection? who cares if the bleachers are hurt by lightning? and there is no practical way to protect people sitting in them from lightning, even if you could protect the bleachers themselves.
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Suppose the bleachers were somehow energized by the conductors serving the field lights. Wouldn't grounding be a good idea, for protecting spectators and providing a pathway to operate the OCPD?
 
gadfly56 said:
Suppose the bleachers were somehow energized by the conductors serving the field lights. Wouldn't grounding be a good idea, for protecting spectators and providing a pathway to operate the OCPD?
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Well then we probably better make sure we bond to all the cars in the parking lot also for the same reasons.
 
bradmaggard said:
We are wiring a new football stadium which utilizes metal bleachers. The engineer has not added any type of grounding or lightning protection to these bleachers. Is there any requirement for this and if not, is it a good idea to do so, or does it cause the potential for other hazards?
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Welcome to the forum!
I know of no requirement in the NEC.
 
If they are likely to become energized then they probably should be bonded to the equipment grounding conductor of whatever circuit may energize them, otherwise what is going to energize them? As far as lightning goes, the metal bleacher is a conductor, the lightning is not too likely to do any serious damage to them, maybe somewhat minor burns where arcing jumps from this conductor to something else. Hopefully there are no people around during a lightning storm anyway, bad place to be even if the bleachers were non conductive.

One other situation where bonding them may be worth consideration may be if they were sitting directly under a high voltage transmission line to reduce induced voltages, but how likely is it that they will be that close to such lines?
 
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gadfly56 said:
Suppose the bleachers were somehow energized by the conductors serving the field lights. Wouldn't grounding be a good idea, for protecting spectators and providing a pathway to operate the OCPD?
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again I ask - what do you mean by grounding? are you thinking to pound in a ground rod next to a bleacher and connect a wire from the bleachers to the rod?
 
kwired said:
Well then we probably better make sure we bond to all the cars in the parking lot also for the same reasons.
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OK, that's just a little ridiculous. When you exit a car you don't normally contact metal and ground at the same time, plus you're only going to have 1-4 people entering/exiting at once. The exterior handle is typically metal, but may or may not have a good path to the car's body. The car is typically painted (classic DeLoreans aside) and may include plastic panels (a la Saturn) additionally limiting contact. Metal bleachers can hold hundreds of people, the aluminum isn't coated and when you step off you typically DO make contact with the ground. Just sayin'.
 
petersonra said:
again I ask - what do you mean by grounding? are you thinking to pound in a ground rod next to a bleacher and connect a wire from the bleachers to the rod?
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Shouldn't hurt anything, but isn't necessary either - in general until there is something that may energize it, then see my last post in this thread.
 
petersonra said:
again I ask - what do you mean by grounding? are you thinking to pound in a ground rod next to a bleacher and connect a wire from the bleachers to the rod?
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EGC to the panel.

I admit this is way outside our usual wheelhouse. But would grounding be a bad idea? Just remember, code is the minimum that's required.
 
gadfly56 said:
Metal bleachers can hold hundreds of people, the aluminum isn't coated and when you step off you typically DO make contact with the ground. Just sayin'.
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Aren't the metal bleaches in intimate contact with ground already? Every metal bleacher structure I have seen is either sitting on the ground or it is on supports which have been pounded into the ground.
 
gadfly56 said:
EGC to the panel.

I admit this is way outside our usual wheelhouse. But would grounding be a bad idea? Just remember, code is the minimum that's required.
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Bad idea - no, worth whatever benefits may be gained - probably not worth that either. What if these are portable bleachers and are moved on a regular basis? That does happen around here at some small facilities, field may be a football and baseball field, they move portable bleachers onto the an unused part of baseball part of field when playing football, there is nothing electrical in the vicinity that would present any risk of energizing it.

How about metal bleachers with concrete below, or even metal bleachers with support members embedded in concrete? Chances are the whole assembly is already a better electrode than any driven ground rod. Now only bond it to electrical system if there is an electrical system nearby. Some places there may be nothing electrical within 50, 100, maybe even 200 feet. If there is no lighting for the playing field - maybe even farther.
 
If there are wiring methods going through the bleachers feeding an electrical load, then the bleachers will be bonded to that circuit/feeder. Other than that driving a ground rod next to the bleachers does not serve any purpose. Besides how many grounding rods or groundinng electrodes are you going to install? 1, 5, 10,....
 
gadfly56 said:
When you exit a car you don't normally contact metal and ground at the same time...
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Au contraire. On cool clear days with low humidity I frequently get shocked exiting my car when my foot hits the ground and my calf is touching the door frame.
 
gadfly56 said:
OK, that's just a little ridiculous. When you exit a car you don't normally contact metal and ground at the same time, plus you're only going to have 1-4 people entering/exiting at once. The exterior handle is typically metal, but may or may not have a good path to the car's body. The car is typically painted (classic DeLoreans aside) and may include plastic panels (a la Saturn) additionally limiting contact. Metal bleachers can hold hundreds of people, the aluminum isn't coated and when you step off you typically DO make contact with the ground. Just sayin'.
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Missed this reply somehow - what does it matter if there are 1-4 people vs 100's or whether or not you "typically" contact insulated parts and the ground at the same time or not? They both are conductive bodies and you can touch the conductive part and ground at same time with both, now enter with possibilities of whether either one has much chance of becoming energized.

Like I said earlier, if metal bleachers with metal supports embedded in concrete footings - you are not going to get much better of an electrode anyway. If they are portable, maybe they are more prone to voltage differences but need a source of voltage or you still don't have a problem.
 
gadfly56 said:
EGC to the panel.

I admit this is way outside our usual wheelhouse. But would grounding be a bad idea? Just remember, code is the minimum that's required.
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"Grounding"? We are still not sure what you mean. Try this. If you connect a wire the bleachers what color is it and what does it do?
 
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