Help needed please

[N2ETC]

Hi there.

I have just done some work in my garage! I have put in a new ring main and two new lights. I had to replace the consumer box in the garage as it had the wrong fuses and have now got a 6a for the lights a 32a for the ring main and the RCD is a 40a. I installed all the wiring and proceeded with the testing which on the dead tests went fine and got good readings. When I came to test polarity on the live tests the fuse in the main fuse box kept tripping when I tested live to earth. The fuse in the house is on a 32a and this I changed from a 16a which was on there previously. I still couldn't work out why it kept tripping and thought I would continue as I am newly qualified electrician and wanted to practice the rest of the tests. Also when I got to the RCD test rather than tripping out the RCD in the garage it tripped the fuse in house instead. Question do I need the fuse in the house to be the same size as the RCD in the garage so a 40a or do i have another problem. All the sockets and lights work but very puzzled please help somebody

 

[monkeyelectric]

Hi there.

I have just done some work in my garage! I have put in a new ring main and two new lights. I had to replace the consumer box in the garage as it had the wrong fuses and have now got a 6a for the lights a 32a for the ring main and the RCD is a 40a. I installed all the wiring and proceeded with the testing which on the dead tests went fine and got good readings. When I came to test polarity on the live tests the fuse in the main fuse box kept tripping when I tested live to earth. The fuse in the house is on a 32a and this I changed from a 16a which was on there previously. I still couldn't work out why it kept tripping and thought I would continue as I am newly qualified electrician and wanted to practice the rest of the tests. Also when I got to the RCD test rather than tripping out the RCD in the garage it tripped the fuse in house instead. Question do I need the fuse in the house to be the same size as the RCD in the garage so a 40a or do i have another problem. All the sockets and lights work but very puzzled please help somebody

hiya, is it the rcd or mcb tripping on live to earth? you can't have 2 30mA rcd's inline you'll have to do away with the one in the garage and just use a main switch

 

[acat]

Bit confused as to what is actually tripping out "fuses" do you means MCB or RCD

RCD detects an imbalance between live and neutral


MCB protects against overcurrent and short circuit.


Hope that helps point you in the right direction



Chris

 

[Golden_Boy]

Hi there.

I have just done some work in my garage! I have put in a new ring main and two new lights. I had to replace the consumer box in the garage as it had the wrong fuses and have now got a 6a for the lights a 32a for the ring main and the RCD is a 40a. I installed all the wiring and proceeded with the testing which on the dead tests went fine and got good readings. When I came to test polarity on the live tests the fuse in the main fuse box kept tripping when I tested live to earth. The fuse in the house is on a 32a and this I changed from a 16a which was on there previously. I still couldn't work out why it kept tripping and thought I would continue as I am newly qualified electrician and wanted to practice the rest of the tests. Also when I got to the RCD test rather than tripping out the RCD in the garage it tripped the fuse in house instead. Question do I need the fuse in the house to be the same size as the RCD in the garage so a 40a or do i have another problem. All the sockets and lights work but very puzzled please help somebody

Consumer "BOX"???
FUSES ???
Testing Live to earth ( what test ??? loop test or insulation ? )

 

[m4tty]

When your carrying out your polarity test i take it your using a Fluke T100 or the like which when testing Live to Earth will trip the RCD. You need to hold the tester Live - Neutral for 5 secs to charge the Fluke then do Live to Earth and it wont trip the RCD. HTH unless ive got wrong end of the stick

and as said above you cant have 2 x 30ma RCD's in series as theres no discrimination and both or either will trip. Need to remove the one in garage and swap for mainswitch hth

 

[N2ETC]

Hi again

Ok sorry not fuses MCB's. Yes MCB on Main Consumer Unit tripping. In the garage there is a RCD and the MCB on the Main Consumer box is also on an RCD. So basically your saying I don't need a RCD in the garage even though there was one before?

The test was just the first test in order in the live testing which was live polarity every time I testing between live and earth the MCB in the main consumer unit it tripped??

Thanks for responding so quickly this has been doing my head in!

Also when doing my PFA test i got a reading of 2.2KA is this right?

 

[m4tty]

The MCB in the house CU was tripping and not the RCD ?

The MCB detects overload and short circuits so there must be a problem there somewhere. Will it power up without tripping the house end out?

Sorry im not to good at explaining things and im sure someone more knowledgeable will be along soon

Cheers

PFC would mean your Zdb is about 0.10 Ohms roughly

 

[N2ETC]

No your are right, sorry my heads all over the place yes the RCD is tripping? And you sound very knowledgeable I appreciate your help!

Hi my Ze reading was 1.91 I'm not sure if my testing is right?

 

[m4tty]

No worries glad i can help mate. If you was using a Fluke T100 try charging it doing what i mentioned above and see if it still trips the house RCD as it shouldnt. HTH

Someone more knowledgable will be along in a minute as im confused a bit now. Doing my Level 3 atm so im still learning too. Cheers

 

[Guest123]

Hi my Ze reading was 1.91 I'm not sure if my testing is right?

Hi.

Doesn't sound quite right to me, where did you take this reading??

What earthing system do you have there - TT, TN-S, TN-C-S???

 

[N2ETC]

You've been great thanks ever so much! I think I will start again with my testing I've only just got my new tester to I'm still getting to grips with it!

Thanks once again and I will try your suggestion, the fact that everything is working and I've got some good readings I can't really see what the problem is!

Hi Lenny

Yes not good reading I'm going to have another go got a Mega and don't think its on the right setting, but thank you very much!