Eic / eicr testing question

[driverman]

Hi guys, i'm not into testing on a regular basis. When testing a new build, all dead test done first. Energise installation when everything !00% ok.
How do you guys take Zs readings on "live" radial circuits?. If carrying out an EICR on an existing installation how is the Zs obtained on "live" radial circuits? Appreciate your thoughts.

 

[telectrix]

just connect MFT to socket/light/whatever. perform loop impedance test. readings should increase the further along the radial you go. if RCD protected circuit, use the lo setting. most MFTs will require 3 lead connections for lo setting.

 

[Flanders]

If you feel it is unsafe to carry out a live test on a circuit you can do an R1 + R2 test and calculate the Zs, there are also various adapters on the market for plugging into light fittings to help with the testing

 

[telectrix]

If you feel it is unsafe to carry out a live test on a circuit you can do an R1 + R2 test and calculate the Zs, there are also various adapters on the market for plugging into light fittings to help with the testing

as long as you don't have megger test leads. they no work with lightmates.

 

[driverman]

re Zs testing I as thinking on the lines of radial circuits like Imm/htrs. Showers Cooker circuits with no 13a skts. I have done Zs testing before on radial cicuit , but now been informed that it is against the law Electricity at Works Act 1989.

 

[telectrix]

not against the law. EWAR states that live working should only be undertaken when absolutely necessary. live testing is not the same as live working. it is , however, acceptable to calculate Zs from Ze and R1+R2 if you feel it's safer to do it that way.

 

[driverman]

not against the law. EWAR states that live working should only be undertaken when absolutely necessary. live testing is not the same as live working. it is , however, acceptable to calculate Zs from Ze and R1+R2 if you feel it's safer to do it that way.

Thanks........I've just watched a NICEIC dvd re testing, so thought I'd ask the question. they are basically saying apart from the ring main, Zs to be worked as you said above.

 

[Flanders]

As long as you have insulated test probes and have check the connections are sound during relevant dead testing, I can't see any danger in carrying out a Zs test at spur or light switch. But as mentioned a Calculated Zs is accetable on an EICR