Unit 304E

TT earthing systems are often found using a ........... to acheive disconnection times?

• MCBs

• RCD

• HBC Fuses

• Rewireable fuses

What earthing arrangement uses the mass of earth as a earth fault return path

• IT

• TN-S

• TN-C-S

• TT

Three phase supplies have 3 supplies at ........degrees apart?

• 90

• 180

• 270

• 120

Earth electrodes are used on which of the following systems?

• TN-S

• TN-C-S

• TT

• IT

Diverted neutral currents are an issue that can arise on which earthing sytem?

• TT

• TN-S

• TN-C-S

• IT

An example of a exposed conductive part is a?

• metal clad light switch

• anything that is metal

• a class II light switch

• a metal water pipe

If metalwork from outside the installation introduces a potential usually 0 volts into a premises it is a?

• circuit protective conductor

• main earthing conductor

• exposed conductive part

• extraneous conductive part

The ac term for resistance is?

• ohms

• reactance

• impedance

• capacitive

The term given to check if a circuit protective conductor is able to carry fault current is?

• Thermal constraints

• shock constraints

• current constraints

• voltage constraints

Shock constraints refers to whether a protective device will?

• protect against electric shock

• disconnect in a given time

• cause an electric shock

• not operate