Sanity check - replacing MCBs with RCBOs

[drjarmin]

Hi All

Wanted to get feedback on this idea.

I have 3 fuse boards which trip frequently whenever there is a lightening storm nearby. My electrician friend has suggested he swaps all the MCB's with RCBO's so that individual circuits trip rather than the whole board. Each board currently has a main RCB for protection - the proposal is to replace it with a 63A MCB.

1. Is this a good idea? I can't see a downside other than cost.

2. Any other thoughts on how to stop these boards tripping everytime there is a burst of lightening nearby?

Thanks!

 

[drjarmin]

Understood. As I said he did find a fault on the garden lights circuit and the lights are letting water in. But couldn't explain the other two boards tripping (one on each floor). They only trip when there is lightning. There will be a flash of lightning outside and on one, two or all three boards the RCB will trip. The most times this has happened is 35 over the course of a night. Agree this doesn't identify the root cause but isn't it better to lose a circuit rather than the whole board? Seems odd for a fault to be impacting all relatively new boards? They were installed about 5 years ago on the back of a complete rewire.

He also told me that the RCBs may be overly sensitive as I have all electrical devices in the house coming off surge protectors. This could be total cobblers but that's what he said.

I'm a bit short of options here. Local electricians basically will use any cable that's lying around at the time regardless of colour coding or width. They also don't seem to care about earthing stuff and will join wires by wrapping the wires and wrapping them in electrical tape and then happily leaving that join buried in conduit! Found a lot of that when the old original wiring was pulled out.

 

[trev]

The thing is there's no guarantee that when there's lightning it won't take out all the RCBOs. There's a reason why tripping happens and that is what needs to be found.

 

[telectrix]

sybil fawlty. specialist subject... the bleeding obvious. :6:

 

[Rockingit]

OP, when it's stormy, do your neighbours also get affected or is it just you? Are you in an apartment block or a standalone house?

 

[Gavin A]

is the answer to this question not - surge protection?

How does the incoming supply come in, is it underground cable or pole mounted?

I'm betting it will be pole mounted for a long run, and what you're experiencing is the impact of lightning induced surges on your incoming supply.

best to solve the actual cause of the problem, rather than treating the symptoms IMO.

 

[trev]

The answer could well be surge protection Gavin but as you say, it's going to be better in the long run to find out. It could well be some things are getting wet during the storms.

 

[Gavin A]

ps if this was UK regs it'd be under reg 443.2.3 for installations supplied by overhead cables and subject to >25 thunderstorms per year.

 

[Gavin A]

The answer could well be surge protection Gavin but as you say, it's going to be better in the long run to find out. It could well be some things are getting wet during the storms.

if it's an overhead line, and there's no surge protection device, then it's almost certainly this - notice the poster only refers to lightning, not 'every time it rains'.

 

[drjarmin]

if it's an overhead line, and there's no surge protection device, then it's almost certainly this - notice the poster only refers to lightning, not 'every time it rains'.

Yes. Only lightning. Rain isn't an issue. Had another storm tonight and the most vulnerable board with the rcdo's for once didn't trip. Only the top floor board. Progress?

The cables feeding the meters come from underground.

There are two 4' earth rods either side of the house in to wet clay. Not sure if this is relevant.

My only neighbours are next door with shared walls. I don't know if their board trips because it's their holiday home and they visit every couple of months. I haven't asked them.

 

[Gavin A]

is that underground all the way from the local transformer, or is it pole mounted from the transformer, then goes underground just before the house?

 

[drjarmin]

Underground. Nearest substation is about a mile or so away.

 

[drjarmin]

To the OP, I don't think for one moment that you're being serious, but just in case you are, I've spent most of my life flying all over the world doing electrical and related work, pm me if you want to book a slot in my diary. As I remember, HK has this strange blend of UK and Chinese methods, and I'd guess that even now most work has to be done to UK standards to conform to what existed before?

I'll send you a pm.

 

[drjarmin]

That board is a mess mate, it backs up my statement earlier that your electrician friend is not what he claims.
My offer still stands, I'll compromise and travel business class but you'll be left with a safe, easy to use installation at the end of it

Trev, for my understanding what is wrong with that board? I can see the neutrals and earths for the rcbos need tidying up but other than that are there other fundamental issues that should be addressed?

 

[drjarmin]

The thing is there's no guarantee that when there's lightning it won't take out all the RCBOs. There's a reason why tripping happens and that is what needs to be found.

Yes, I can see what you mean. Is the solution to fit something like this to each board?

Surge Protection Protection Devices

 

[trev]

Trev, for my understanding what is wrong with that board? I can see the neutrals and earths for the rcbos need tidying up but other than that are there other fundamental issues that should be addressed?

Well the way the top row has been fed leaves an awful lot to be desired, the cabling needs a damn good tidy up. There could also be further, more serious issues in there but only time and testing would prove that.

Yes, I can see what you mean. Is the solution to fit something like this to each board?

Surge Protection Protection Devices

Surge protection may well solve the problem but as I've said earlier in reply to another poster it could be something as simple as something else is getting wet but only someone with proper test equipment and the knowledge of how to use it could tell you that for definite

 

[drjarmin]

Thanks Trev

A bit like having a hole in your bucket, if I could find someone competent I wouldn't be in this mess in the first place.

 

[trev]

Thanks Trev

A bit like having a hole in your bucket, if I could find someone competent I wouldn't be in this mess in the first place.

Well if post #42 means what I think it could then you've found someone more than competent mate

 

[drjarmin]

Well if post #42 means what I think it could then you've found someone more than competent mate

Finances permitting!!