Clean grounding for medical locations

[m sleem]

Do we have anything in code says it's mandatory to have a separate (clean) earth for medical locations? i would think it is required for the IPS only.

 

[roger]

Do we have anything in code says it's mandatory to have a separate (clean) earth for medical locations? i would think it is required for the IPS only.

No, there is no code requiring a separate Grounding Electrode for Medical facilities or equipment and is in fact a violation of the NEC. There can only be one Grounding Electrode System.

250.50 Grounding Electrode System.
All grounding electrodes as described in 250.52(A)(1) through (A)(7) that are present at each building or structure served shall be bonded together to form the grounding electrode system. Where none of these grounding electrodes exist, one or more of the grounding electrodes specified in 250.52(A)(4) through (A)(8) shall be installed and used.

Roger

 

[dereckbc]

Article 517 is not my area of expertise but if you mean Isolated Ground Receptacles (IGR) then the answer is NO, they are not required but permitted. However 517.13 does have some special requirements which basically amount to there must be two plannned paths for equipment bonding conductors. For example a standard EBC and metallic raceway. I suggest you read and understand the options.

517.13 Grounding of Receptacles and Fixed Electrical
Equipment in Patient Care Areas. Wiring in patient care
areas shall comply with 517.13(A) and (B).

(A) Wiring Methods. All branch circuits serving patient
care areas shall be provided with an effective ground-fault
current path by installation in a metal raceway system, or a
cable having a metallic armor or sheath assembly. The
metal raceway system, or metallic cable armor, or sheath
assembly shall itself qualify as an equipment grounding
conductor in accordance with 250.118.

(B) Insulated Equipment Grounding Conductor. The
grounding terminals of all receptacles and all non?currentcarrying
conductive surfaces of fixed electrical equipment
likely to become energized that are subject to personal contact,
operating at over 100 volts, shall be connected to an
insulated copper equipment grounding conductor. The
equipment grounding conductor shall be sized in accordance
with Table 250.122 and installed in metal raceways
or as a part of listed cables having a metallic armor or
sheath assembly with the branch-circuit conductors supplying
these receptacles or fixed equipment.

Exception No. 1: Metal faceplates shall be permitted to be
connected to the equipment grounding conductor by means
of a metal mounting screw(s) securing the faceplate to a
grounded outlet box or grounded wiring device.
Exception No. 2: Luminaires more than 2.3 m (71?2 ft)
above the floor and switches located outside of the patient
care vicinity shall be permitted to be connected to an
equipment grounding return path complying with
517.13(A).

 

[m sleem]

No, there is no code requiring a separate Grounding Electrode for Medical facilities or equipment and is in fact a violation of the NEC. There can only be one Grounding Electrode System.

Normally the IPS is isolated from the building's grounding network, means that there is no EGC. the connection is direct from the IPS to the grounding module, and the grounding module is connected directly to the GEC.
Clean means as i understand the GEC is not connected to the building grounding in earth. As you elaborated that would be a violation in NEC.
I would think if isolate the IPS from the building grounding (especially in OR) that will be good to protect the medical equipments from the building noise and ground faults.

 

[roger]

I would think if isolate the IPS from the building grounding (especially in OR) that will be good to protect the medical equipments from the building noise and ground faults.

One way to take care of noise issues is to use Isolated Power Systems for the OR's. They were originally introduced in OR's to minimize dangers associated with flammable anesthesia, but they also offered other safety as well noise reduction.

See the link below.


http://www.pglifelink.com/pdf/isolated-power-explanation.pdf

Roger