Lecture 9: Electrical Safety Testing

Question 1

Functional earth

Answer 1

An earthing circuit that ensures correct operation of electrical devices that enables reliable and proper functioning of electrical installations. When the Earth is connected to the Extra Low Voltage circuit of the CP in a class I device this Earth is a Functional Earth as it holds that common to the circuit to 0 Volts

Question 2

Protective Earthing

Answer 2

If a fault occurs between a live part and exposed conductive parts of the protective earthing system of the device, a touch voltage arises between simultaneously accessible conductive parts that draw a LARGE amount of current. Fault protection by means of automatic disconnection of supply is intended to limit this voltage/current.

Question 3

Equipotential Earthing

Answer 3

the Protective Earthing Systems become Equiponential Earthing Systems only when plugged into an EP wiring system in a Cardiac Protected Area

Equipotential earthing in treatment areas used for cardiac procedures is intended to minimise any voltage differences between earthed parts of equipment and any other exposed metal in the room.

Question 4

Electrical safety tests?

Answer 4

Visual Inspections
Protective earthing tests
Insulation resistance tests
Touch current tests
Earth leakage current tests; Applied part leakage current tests
Mains contact current tests