All three RCD's tripped

Dutchbyname · Mar 12, 2016

Good evening every body.
Im new here so hello to one and all

I have a question. I plugged my new 1710 Megger into a TSO in a garage with a two way board on a 30ma RCD. I did an RCD check and my X1 took the RCD out in the garage and the board in the workshop and the main house one too..
I couldn't afford a new trip MFT bug I'm not sure why all three RCD tripped. Time on the test was 37ms so maybe a bit high but doesn't explain the other two. I done no more testing on the installation yet btw
can anybody advise

thsnk you.

Dutch

Sintra · Mar 12, 2016

Dutchbyname said:
Good evening every body.
Im new here so hello to one and all

I have a question. I plugged my new 1710 Megger into a TSO in a garage with a two way board on a 30ma RCD. I did an RCD check and my X1 took the RCD out in the garage and the board in the workshop and the main house one too..
I couldn't afford a new trip MFT bug I'm not sure why all three RCD tripped. Time on the test was 37ms so maybe a bit high but doesn't explain the other two. I done no more testing on the installation yet btw
can anybody advise

thsnk you.

Dutch

Sounds like the installation is badly designed with 3 RCD's in series which does not provide any discrimination between the devices. 37mS for a X1 test is by no means high.

uksparks · Mar 12, 2016

Quite often you find old 16th edition hager RCD's seem to trip in around 180ms, an MEM one I looked at yesterday was 68.9ms I think.

Octopus · Mar 12, 2016

How are the 3 boards connected? Or are they independent?

Sounds a bit dodgy to me

Dutchbyname · Mar 12, 2016

Sintra said:
Sounds like the installation is badly designed with 3 RCD's in series which does not provide any discrimination between the devices. 37mS for a X1 test is by no means high.

Thank you for your reply

Richard Burns · Mar 12, 2016

Welcome to the forum.

Sintra has the answer for you there.
Each board is fed from the previous board each of which has a 30mA RCD.

[ElectriciansForums.net] All three RCD's tripped

Dutchbyname · Mar 12, 2016

Ok. Than you very much for your response

Dutchbyname · Mar 12, 2016

wow that's a great post Sintra. Thank you very much. It's over RCDed then! Could therefore the garage RCD just have a main switch in it?

telectrix · Mar 12, 2016

Richard Burns said:
Welcome to the forum.

Sintra has the answer for you there.
Each board is fed from the previous board each of which has a 30mA RCD.
View attachment 31757

nice pic. looks like a camel which is a horse designed by a kitchen fitter. bad design.

Dutchbyname · Mar 13, 2016

Hi. There is a 6mm from house to workshop (workshop attached to the side of the house) which supplies the board. This has simple lighting and a few socket outlets)
from there that board via an amoured cable runs up the garden to a garage where you have a couple of lights and two sockets. Garden is about 15m long

Octopus · Mar 13, 2016

A bit scary that somebody with a mft doesn't understand rcd's

Richard Burns · Mar 13, 2016

Once you have confirmed the wiring arrangement is as described above then it would be possible to replace the garage RCD with a main switch, however this will mean that any fault will trip the workshop or house breakers which will take a out a lot more than just the garage and require you to go back to those locations to reset.
Ideally you would have independent RCD protection local to the garage to minimise the tripping of non faulty supplies and make it easier to reset.

Dutchbyname · Mar 13, 2016

Thank you Richard. Much obliged.

Risteard · Mar 15, 2016

uksparks said:
Quite often you find old 16th edition hager RCD's seem to trip in around 180ms, an MEM one I looked at yesterday was 68.9ms I think.

What is a 16th Edition RCD?

All three RCD's tripped

Dutchbyname

Sintra

uksparks

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Octopus

Dutchbyname

Richard Burns

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Dutchbyname

Dutchbyname

telectrix

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Dutchbyname

Octopus

Richard Burns

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Dutchbyname

Risteard

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