iso grd recepts in cath lab

[brentp]

The plans call for an isolation panel in a cath lab with iso grd recepts. The grd wires from the recepts are shown to terminate on the reference grd bus in the iso panel. The plans also call for a seperate grd wire from the reference grd bar to all metal boxes, med gas recepts, film illum...etc.

I don't understand the purpose of the iso grd recepts when the grd wires terminate at the same place as the equipotential grding. Can anyone help me out with this?

Brent

 

[roger]

Re: iso grd recepts in cath lab

Hello Brent, I actualy see it as defeating the intended redundant grounding of 517.13.

It is allowed per 517.16 (see the FPN) but is a poor design IMO. I don't think any of the equipment in the room needs isolated grounding for noise or any other reason. The receptacles aren't realy part of the equipment anyways.

I have never seen isolated ground receptacles in any cath lab I have done or been involved with.

Roger

[ July 16, 2004, 07:51 PM: Message edited by: roger ]

 

[brentp]

Re: iso grd recepts in cath lab

Thanks Roger.

I haven't seen this design in cath labs, or O.R. rms. I don't get it.

I need some 'backup' before I talk with the engineer.

Brent

 

[ron]

Re: iso grd recepts in cath lab

Brent,
Where is the closest upstream neutral to ground bond from the isolated ground panelboard? Does it occur in that panelboard (maybe the first disconnect after a SDS)

[ July 17, 2004, 02:33 PM: Message edited by: ron ]

 

[roger]

Re: iso grd recepts in cath lab

Ron, the EGC in this panel is already isolated, or to be correct, I should say the winding/s or source is isolated because there is no grounded conductor, the EGC on the primary side would be from a remote panelboard.

Using items that reference EGC's for operation (i.e. some PC power supplies) can cause problems on these systems due to coupling one side of the secondary to a grounded point, and in essence creating a grounded system. This is the reason there are "hospital grade" TV's, PC's, etc... listed for use on "Isolation Systems" and designed for this application

The bonding for these systems are for equipotential.

Roger

[ July 17, 2004, 03:16 PM: Message edited by: roger ]