4mm cable into the bottom of main switch.

Steve93 · May 31, 2019

Eicr today had a 4mm T+E connected into the bottom of a main switch which went to a separate dB with 1 20amp rcbo. Then swa to a hot tub. That part is fine. What I’m unsure about is the reg I can say that the cables are not ok in the bottom of the main switch. The other dB is only about a ft away from the main one. What’s people’s thoughts on this? I know it’s rough as you like!!

Dustydazzler · May 31, 2019

Steve93 said:
No the load side of the dB main switch

So yes then

Ian1981 · May 31, 2019

Hager boards have conductors to an SPD sticking out of their load side main switch all be it in 6mm

davesparks · May 31, 2019

buzzlightyear said:
code c1 it it will not conform has you can not rely on to isolate the second db board .

Not a C1 as it is not immediately dangerous, a C2 at worst but most likely a C3 or no code.

digger123 · Jun 1, 2019

[QUOTE - So the 4mm is protected by the cut out fuse?]

For fault current yep but depends on what type supply

[QUOTE So by the cut out fuse then?
What other ocpd is there?]

What over current can the 4mm suffer when it can pull no more than 20 amp?

M-Ty · Jun 1, 2019

Ian1981 said:
(So by the cut out fuse then?)
What other ocpd is there?

It's the 20-A RCBO, as per original post.

Ian1981 · Jun 1, 2019

digger123 said:
[QUOTE - So the 4mm is protected by the cut out fuse?]

For fault current yep but depends on what type supply

[QUOTE So by the cut out fuse then?
What other ocpd is there?]

What over current can the 4mm suffer when it can pull no more than 20 amp?

Overload protection is not the issue,How about short circuit protection?

Wilko · Jun 1, 2019

Could get a little toasty if the 1.5mm cpc ever got across the 100A fuse ...

Marcus Vaughan · Jun 1, 2019

Watching with interest - what I can't follow is where this 4mm comes from.

It must come from another db/ocpd?

gazdkw82 · Jun 1, 2019

Assuming the main switch is a 100a/60a main switch then the 4mm is not suitable protected for over current and fault protection.

It's a c3 for me

Ian1981 · Jun 1, 2019

M-Ty said:
It's the 20-A RCBO, as per original post.

No it’s not that is it will protect the 4mm against overload but short circuit protection is by the cut out fuse.

Ian1981 · Jun 1, 2019

davesparks said:
Not a C1 as it is not immediately dangerous, a C2 at worst but most likely a C3 or no code.

That narrows it down Dave haha

gazdkw82 · Jun 1, 2019

The problem is, you can't rely on the 20a rcbo to protect the 4mm. What I mean by this is, future alterations, who's to say someone won't split that 4mm and feed something another db etc. There is nothing to protect that 4mm from overload.

It's the same as having a 1.5mm t+e for a lighting circuit protected by a 45a but at fused down to 6a at the first luminaire.

Marcus Vaughan · Jun 1, 2019

Marcus Vaughan said:
Watching with interest - what I can't follow is where this 4mm comes from.

It must come from another db/ocpd?

Sorry - confused by the post - I think the question I'm asking is what exactly is upstream of that main switch - what goes into the top?

Pete999 · Jun 1, 2019

gazdkw82 said:
Assuming the main switch is a 100a/60a main switch then the 4mm is not suitable protected for over current and fault protection.

It's a c3 for me

It's a Bolls up for me

Richard Burns · Jun 1, 2019

A very poor installation but could be compliant if the connections are sound and the cable route to the 20A RCBO is suitable, then the RCBO can provide sufficient protection to be acceptable.
However there are a lot of caveats to the compliance so not generally a good idea.