RCD wont stay in.

[wing nut]

Can anybody tell me if I'am doing anything wrong.
I have a Metrel 3100 multifunction tester. Im trying to do a ze on a tt system.
There is 2 boards, 1 2-way and 1 8-way. Both protected by a 30ma rcd. Used as main switch for both boards.
I have isolated both boards and removed the main earth from a seperate earth terminal which goes out to the rod.
I have my tester on no trip and use a 3 lead test.
But everytime I go to test (the 8-way board) the rcd trips.
Any ideas will be greatfully received.

 

[telectrix]

all wrong, mate.

1. isolate CU.
2. disconnect main earth cable from the CU (or separate MET if fitted)
3. set tester to hi. (not no trip).
4. connect tester between the LIVE at the top of the mainsw/rcd, and the earth lead which is still connected to the rod.

N.B. remember safe working practice.connect live on last and live off first

 

[Octopus]

In Metrel setting tester speak:

Z Loop, RCD

Off you go

 

[Guest123]

The RCD shouldn't trip as it should be OFF before you start disconnecting the main earthing conductor.

Do you have/know what GN3 is???

 

[wing nut]

Everything is off before removing earthing conductor. The rcd is also the main switch. So when turned back on to do test it trips when the test is being carried out.

 

[Octopus]

Are you saying there is a single 30mA RCD between the DNO fuse and the 2 CU's?

 

[topquark]

Everything is off before removing earthing conductor. The rcd is also the main switch. So when turned back on to do test it trips when the test is being carried out.

You don't turn it back on to do the Ze test!

 

[telectrix]

double post

 

[telectrix]

to be honest, mate, i'd not do any testing on your own till you've had some further tuition.

 

[Amp David]

Sounds like the Ze is being done on the load side of the RCD:13:

 

[Guest123]

Buy this & read it cover to cover a couple of times.....please for your own sake AND other peoples safety!!!!


Guidance Note 3: Inspection and Testing Guidance Notes for Bs 7671: Amazon.co.uk: Jon Elliot: Books