Bonding of essential and normal systems

[rick hart]

RE: 517.14 2005
In an hospital of several floors where panelboards are set on every level to serve patient care vacinity loads, does each panelboard EGC terminals require bonding together? Or, is bonding the two systems where they originate, in the basement for example, and an insulated bonding conductor is ran, meet this requirement?

It would seem to me that as long as the different systems are bonded at the source, bonding at each floor would be creating a secondary ground/bond loop.

 

[roger]

Re: Bonding of essential and normal systems

Rick, this would only be for the panels of different systems serving the individual Patient Vicinity's. In other words, the panels serving areas on the 3rd floor wouldn't need to be tied to the panels serving areas on the 5th floor.


Roger

 

[rick hart]

Re: Bonding of essential and normal systems

I guess I wasn't clear about the circumstances. It is hard to be short and cover everything....
Let me try again.
Two outlets on either side of a patient bed- one normal, one emergency- each fed from a panelboard from a closet on that floor. Each of those panels are tapped from separate busduct risers with a disconnect for both the normal and emergency panels. This same scenario is repeated on 3 wings, 9 floors. The question is - Does each wing of each floor's panelboard need to be bonded to each other at the wing and floor that serves the bedside?
Or, does bonding the emergency and normal system panel equipment ground together at the origin of the riser with an insulated conductor to the EG terminal comply with 517.14?
If a bond is required on each wing/floor, what is used to size the bond wire.
#10 is all that is required? I realize that what is trying to be accomplished here is keeping the ground potential at the patient vacinity identical. Bonding at the source would do that without a bunch of jumpers everywhere. Thanks Roger

 

[roger]

Re: Bonding of essential and normal systems

Rick, Knowing your experience with hospital design, I figured I wasn't getting the jest of what you were asking. Our state agency over hospitals (AHJ) requires us to install this #10 jumper between the panels common to a room per NFPA 99 and the NEC.

Now as far as this

Bonding at the source would do that without a bunch of jumpers everywhere.

I have wondered this also, but I wouldn't have as much success in arguing this point as you would.

Roger

 

[rick hart]

Re: Bonding of essential and normal systems

As far as arguing the point, You have to choose your battles. I'm letting this one go.

After mulling this over, I think it is one of those things that really doesn't do much harm in attaching a #10 bond wire on an equipment grounding terminal. It gets real close to picking up a ground wherever you can find one but as long as the EGC is installed properly there is really no issue. I just can't see a real benefit other than making double sure stray voltage.....or whatever the latest term is, stay away from the patient. Not a bad thing. I just wanted it clear in my mind what is the code requirement.

Thanks for your input Roger

Just to open a can of worms: what if the normal panelboard was a service entrance where the neutral must be bonded to ground and the emergency was a sub panel where neutral and EGC must be kept separate?

 

[steve66]

Re: Bonding of essential and normal systems

Rick:

The extra ground wires you are running go from ground bus to ground bus. As long as they aren't tied to the neutral anywhere (and they shouldn't be), they don't have any effect on the bonding between neutral and ground.

STeve