Ground Bars in Laboratories

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cvirgil467

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NewYork
We recently received an objection from an inspector for installing ground bars in laboratories. The ground bars are for bonding of laboratory equipment such as gas cabinets, and other similar enclosures to place all equipment at the same potential to mitigte potential differences between equipment and users. The floor also has grounding mats that are grounding back to the ground bar.

The ground bar is copper and is exposed (not protected in an enclosure or fence) and the conductors connected to the bar are insulated but not installed in a raceway.

Anyone have any experience with this ground bars in labs and if they pose a life safety issue? I can see a lightning strike being a potential issue and the ground bar being a source of small disipation. Other than that, I don't see this as an issue.

Thanks.
b
 
An electrical inspector? Your bonding is not covered under the scope of the NEC, well maybe under an auxillary ground rod, but that's a stretch.
So ask him what code section applies.
 
It is the unprotected conductors he is arguing. He is not stating a code section. It's his gut feeling.

I should say the the building has a dedicated ground riser specifically for connecting ground bars in the labs. The ground riser is conneted back to the main groudn bar at the service switchboard. The ground bars are conneccted back into the main groudn riser.
 
cvirgil467 said:
We recently received an objection from an inspector for installing ground bars in laboratories. The ground bars are for bonding of laboratory equipment such as gas cabinets, and other similar enclosures to place all equipment at the same potential to mitigte potential differences between equipment and users. The floor also has grounding mats that are grounding back to the ground bar.

The ground bar is copper and is exposed (not protected in an enclosure or fence) and the conductors connected to the bar are insulated but not installed in a raceway.

Anyone have any experience with this ground bars in labs and if they pose a life safety issue? I can see a lightning strike being a potential issue and the ground bar being a source of small disipation. Other than that, I don't see this as an issue.

Thanks.
b
Click to expand...

Man, He'd hate a cell site or a Motorola R56 compliant building........
 
cvirgil467 said:
We recently received an objection from an inspector for installing ground bars in laboratories. The ground bars are for bonding of laboratory equipment such as gas cabinets, and other similar enclosures to place all equipment at the same potential to mitigte potential differences between equipment and users. The floor also has grounding mats that are grounding back to the ground bar.

The ground bar is copper and is exposed (not protected in an enclosure or fence) and the conductors connected to the bar are insulated but not installed in a raceway.

Anyone have any experience with this ground bars in labs and if they pose a life safety issue? I can see a lightning strike being a potential issue and the ground bar being a source of small disipation. Other than that, I don't see this as an issue.

Thanks.
b
Click to expand...

These are used to establish equipotential for the lab spaces. There are various ground network schemes that can be employed for connecting them to the GES (i.e. floating, single-point, multi-point, etc) depending on the function of the labs (low-frequency, high-frequency, EMI control, etc.). They all have their pros and cons but all configurations have to ultimately connect to the facility GES. There is no more safety risk for exposure to these ground bars than exposure to bonded equipment enclosures. Here are a couple links for additional info.

http://www.erico.com/public/library/fep/LT0359_2.pdf

http://www.erico.com/public/library/fep/LT0359.pdf
 
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