Maximum earth loop impedance

[EddieB]

Table 41.3 gives the maximum earth loop impedance on a type B 32a breaker to 60898 as 1.44 ohms, the testing schedule on the domestic cert asks maximum permissble loop impedance, in the test and inspect notes I seem to remember that you are required to write the full 1.44 but I'm sure that you allow for 80% due to fault condition temprature?? bringing it down to 1.15. Answers on a virtual postcard please

 

[Spudnik]

It says on the cert MAX Zs.

This is before any correction is made.

Does seem a a bit daft as i would have thought the corrected value would make more sense as its a tad lower.

 

[hot wire]

testing power and light circuits..
if i have a typeC 20amp RCBO with 4mm cable feeding a radial power cicuit what sort of testing am i doing to get fault loop impedance

 

[malcolmsanford]

A measured Zs or a calculated Zs = Ze + (R1 + R2)

 

[Deleted member 26818]

Table 41.3 gives the maximum earth loop impedance on a type B 32a breaker to 60898 as 1.44 ohms, the testing schedule on the domestic cert asks maximum permissble loop impedance, in the test and inspect notes I seem to remember that you are required to write the full 1.44 but I'm sure that you allow for 80% due to fault condition temprature?? bringing it down to 1.15. Answers on a virtual postcard please

It depends on who's schedules you are using.
The NICEIC ones require the value from BS7671, whereas I believe that with ELECSA it is either the full or the 80%.
Of course, with the IET ones it's neither.

 

[hot wire]

thanks for the replys
im thinking the fault loop impedance testing can only be done when the circuit is live.. im wrong arnt i

 

[telectrix]

no, you are right. LFLI test is a live test. ( unless you want to calculate it, as malcolm.)