The ground wire should not be smaller than No ______ copper.

The ground wire should not be smaller than No ______ copper.

Right Answer is:

10

SOLUTION

Fault currents flowing in the grounding system may cause dangerous differences in potential between the grounded instrument cases and other metal objects, presenting serious shock hazards to the patient. These differences in potential may result from high fault currents flowing in electric conduits or metal raceways sometimes used for the grounding conductor, or in long runs of small ground wires, especially if the wires have defective splices.

As noted in Sec. 720.4, “Conductors shall not be smaller than 12 AWG copper or equivalent. Conductors for appliance branch circuits supplying more than one appliance or appliance receptacle shall not be smaller than 10 AWG copper or equivalent.”

The hazard from ground currents can be reduced by using a continuous insulated short length of copper ground wire (not smaller than stranded No. 12 AWG) connecting each receptacle, or cluster of receptacles to the patient’s grounding bus, and by a similar copper ground wire (not smaller than No 10 AWG connecting the grounding bus to the room grounding bus, and then to the nearest available effectively grounded structural metal member of the building to the nearest grounded water piper and to the grounding bus at the main building supply panel. 

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