no water bond, code query

[IQ Electrical]

Zs is determined as compliant if the nominal voltage over the current causing disconnection in the required time is greater than the measured/ calculated value of Zs. i.e. Zs * Ia <= Uo

so 1.24 x 100A= 124v so my 230v to earth is more so will comply..???

You need the current multipliers of the protective devices for the equation eg:

Type B = X5
Type C = X10
Type D = X20

So max Zs for a B 32 = 230/32X5 = 1.44 Ohms

 

[goldie]

if all circuits was rcd protected , would there be a need for main bonding...

Ofcourse there is! why wouldnt there be?

 

[i=p/u]

i understand that part but how do you know a circuit will comply with a similar summ.. maybe ive picked up wrong what other guy was telling me.. tea?

You need the current multipliers of the protective devices for the equation eg:

Type B = X5
Type C = X10
Type D = X20

So max Zs for a B 32 = 230/32X5 = 1.44 Ohms

 

[IQ Electrical]

i understand that part but how do you know a circuit will comply with a similar summ.. maybe ive picked up wrong what other guy was telling me.. tea?

Because you compare the result of the sum (maximum Zs for the device) with the measured or calculated value of Zs for the circuit.

We use a factor of 0.8 on the maximum Zs figure from the sum to allow for increased conductor operating temperatures under load.

So in the example that I did, you'd take your Zs measurement or calculated value for the circuit and compare it with the value from the sum X 0.8.

As long as your measured/calculated value for the circuit is equal or less than that figure then the circuit is deemed to comply for ADS purposes.

 

[i=p/u]

comprende!! any other tricks up you sleave.. what about this one hope we havent been here before and you getting sore head.. adding of 1.24 for temperature for volt drop and what other cases..??