Earth to garage?

[breaker1]

A good old micc job, the only thing that concerns me is the corrosion on the gland lockrings which may result in a high zs, the suggestion of an rcd is a good one

 

[ban-all-sheds]

Which table are you looking at?

4J1A in the 16th

According to table 4G1A in the 17th ed. 2L2.5 MICC is rated to 31A clipped direct (now ref method 'C')

But unless it's changed from the DPC, 4G1A(17) says the same as 4J1A(16).

See footnote 2 - those cables in the photos don't look PVC covered to me...

 

[p4ult]

Can anyone answer my question?

Shall I run an earth from the switch box to the CU?

 

[JohnD]

yes

and the switchfuse looks to me like a 30Amp one with ceramic rewirable fuseholder, which sounds right for the cable capacity.

 

[p4ult]

Thank you John

 

[p4ult]

Ok guys,

I fitted this bad boy in today, along with a new earth from the switch box to the CU earth.

All I fine until I turn on anything in the garage, light or any socket and then the RCD trips straight away

So im guessing that I have fitted it all ok as the RCD stays on until something is switched on.
As the RCD is tripping im guessing there is a fault with the wiring/earth in the garage????

Is this so???

Thanks again
Paul

 

[333rocky333]

It seems if you fitted the rcd you know how to isolate etc

You need to establish what circuit is tripping it
It may even be a N to E fault

Isolate the main garage supply

At the three way board remove the fuses and disconnect relevant neutrals , remembering what goes where, reconnect one Neutral and fuse (circuit) at a time and by elimination try to find what does and dont trip it
It may be a faulty pyro term , really you need access to an insulation tester

 

[p4ult]

Thanks for your reply Rocky,
One of the 3 must be for the lights, switching these on trips the RCD
At least one of the other two is for the sockets, switching something on also trips the RCD.

So it sounds like its 2 or poss all 3 circuits tripping it here

 

[333rocky333]

Sometimes a fault on one circuit may not trip till a second not faulty circuit is used, thats why you need to only connect one L and N at a time in the board

without a megger its hard

just keep breaking circuit down into sections at a light or a socket
Discon both live and Neutral till you find the clear and the faulty sections

If you have a ohmeter you may pick something up between L and E or N to E testing, with the N Disconned , and may help you find it

 

[p4ult]

Thanks Rocky,
I dont any meters so I will try disconnecting one circuit at a time and see if it still trips.

Thanks

 

[RF Lighting]

Which table are you looking at?

4J1A in the 16th

According to table 4G1A in the 17th ed. 2L2.5 MICC is rated to 31A clipped direct (now ref method 'C')

But unless it's changed from the DPC, 4G1A(17) says the same as 4J1A(16).

See footnote 2 - those cables in the photos don't look PVC covered to me...

My mistake. I forgot to multiply by 0.9

 

[p4ult]

Here are some more pics,

The new DCD with earth

One of the sockets in the garage, this unit is a lot newer and is deffo not from the origional install, will it stil act as an earth? Could this be causing the leakage?

The fuse box opened up, was trying to do as Rocky said, but it all looked to confusing so I will not touch it Also on the wire at the front of the pic, the plastic sheith has started to break up.

 

[333rocky333]

was trying to do as Rocky said, but it all looked to confusing so I will not touch it

Wise move,
only do what you feel confident with
As you did the rcd I would quess you had some understanding

I hope you isolated before dismantling that board
Do NOT risk working on it LIVE

For the cracked neopreen on them cables
sleeve right over it with 3mm or 4mm pvc sleeving, similar to earth sleeving but available in brown and blue or even heatshrink sleeving

 

[333rocky333]

If easier follow the surface pyro from board to first point and disc onnect any ongoing wires there( mark the live with tape !) , you may be able to get circuit clear up to the first point then,which will help

have you a photo of the box above the board with the lid off,where do the pyros from that branch off to

if poss can you do a diagram , and photo it, of where all the pyros go from the board, so we can see what you have

 

[p4ult]

I hope you isolated before dismantling that board
Do NOT risk working on it LIVE

LOL, yes it was all switched off, the RCD, switch box and MCB were off, so power was deffo off. The only thing i didnt do was to switch the main switch on the CU.