EARTHING ARRANGEMENTS AND PROTECTIVE CONDUCTORS

Question 1

any question on sizing of bonding conductors -

bonding conductors link extraneous conductive parts to the M.E.T

Answer 1

sizing of bonding conductors is determined by the sizes of live conductors going into it.
and should refer to table 54.8 on pg 203.

Question 2

Main Earthing Terminal. pg196

every installation needs an m.e.t and is the hub of the earths in the property.

Answer 2

its where all cpc’s connect to. all bonding conductors connect to. most of the time is a external metal terminal next to the consumers unit.

Question 3

protective conductor sizing.
like a seatbelt , it does nothing until theres a fault. an extortionate amount of current goes into a conductor, will it withstand that much current until the protective device starts to operate.

Answer 3

is all down to how much fault Current is present when there’s a fault.

Question 4

s = √I squared X t divided by K.

Answer 4

s - the calculated size of protective conductor
I = the fault current
t - time taken for device to operate (0.1-0.4s)
k - a limiting factor for different cables and instalations

Question 5

questions about what can be used an an protective conductor

Answer 5

top of pg 199. cpcs need to be accessible for inspection , testing and maintenance and no switching device should be on a protective conductor except electronic equiptment.

Question 6

when OCPD are used for fault protection the protective conducter should be..

Answer 6

installed in the same wiring system as live conductors or its immediate vicinity.