Replacing consumer unit - dual RCD vs full RCBO?

Haggisman

Haggisman

Haggisman

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Looking at replacing our ageing fuse box with a more modern CU (since fumbling around with fuse wire in the dark is not fun, never mind having a small child who is getting to the age where he is going to start putting things into sockets).

We have 6 circuits - up and down lights & sockets, plus electric shower and another one I'm not sure of. Is it worth paying the extra for full RCBO? If I understand correctly, it's no safer - more just a convenience thing?

Edit: sorry, should have included, so far we've been quoted £450 to do it with a dual RCD, and ~£200 extra with full RCBO, so it's almost 50% extra
 
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RCBO every single time. I'd get an SPD in too, the extra cost shouldn't be much and it's worth having.

If you have a split load board with 2 RCD's and have a fault with a circuit which trips the RCD then everything hanging off that RCD loses power. With an RCBO board only the affected circuit goes off.
 
As above, i would go full RCBO in my own home, purely due to the convenience of not tripping multiple circuits if you get a trip.
 
I'd personally go full RCBO, even with the increased cost.

However, there's little wrong with dual RCD if you have a relatively small number of circuits. The more circuits you have, the more the cumulative affect of earth leakage resulting in false trips.
 
I've never heard of the latter, but if I was paying for it to be done. I'd pay for the extra at the time

Saying that, my current is dual RCD and I wouldn't be replacing it just for the addition!
 
NoobCannon said:
Prob a good idea to teach your kids not to stick stuff into plug sockets regardless of the type of cu, relying on a piece of equipment is a stupid thing to do.
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WARNING: THIS POST MAY CONTAIN SUBTLE SARCASM. IF YOU ARE EASILY OFFENDED (OR JUST A LITTLE BIT "SLOW"), PLEASE LOOK AWAY NOW!

That's a good point actually, and an option I hadn't considered. Would certainly be cheaper than getting the CU replaced, and would also save a few £ on the lengths of copper wire I was planning to give them after showing them how important it is to push the sprung flap on the earth pin out of the way first

WARNING: THIS POST MAY CONTAIN SUBTLE SARCASM. IF YOU ARE EASILY OFFENDED (OR JUST A LITTLE BIT "SLOW"), PLEASE LOOK AWAY NOW!
 
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Haggisman said:
That's a good point actually, and an option I hadn't considered. Would certainly be cheaper than getting the CU replaced, and would also save a few £ on the lengths of copper wire I was planning to give them after showing them how important it is to push the sprung flap on the earth pin out of the way first
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Muhahahahahaha.

Best post I've seen for a while.
 
Haggisman said:
That's a good point actually, and an option I hadn't considered. Would certainly be cheaper than getting the CU replaced, and would also save a few £ on the lengths of copper wire I was planning to give them after showing them how important it is to push the sprung flap on the earth pin out of the way first
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what is this even supposed to mean. “Its ok kids stick what you like in the socket just don't stick anything in the earth at the same time” what a stupid thing to say.
 
While the the RCBO board is ‘better’ for the reasons stated, but let’s add some perspective. £200 isn’t a small amount of money and it’s for something that might benefit you once in a blue moon.

I think I’ve managed to trip the RCD once in my entire life when the heating element went on on the washing machine.

When the RCD did catch a fault, it did it’s job but it didn’t cause me to think ‘I wish it didn’t also take off the cooker circuit at the same time, I’d better spend an extra £200 to solve that’.

If you are price sensitive, which it sounds like you are, don’t bother, a dual RCD board is fine.
 
b0rn2sk8 said:
...If you are price sensitive, which it sounds like you are, don’t bother, a dual RCD board is fine.
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I have to agree with this. No denying that an RCBO setup is technically better, but you're not getting any additional electrical safety for your money, just convenience in the number of circuits knocked out in a fault. I've only ever had the RCD trip once & you can still isolate at fault circuits with the MCB, so it's not really a big deal. I would get an SPD though - that's definitely useful spend.
 
BUDFORCE said:
To be fair, he did forget to put the OCUK sarcasm warning beforehand lololol.
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Well, maybe his parents should have taught him to avoid sarcasm in the first place. Relying on a piece of text to protect him is a stupid thing to do. Anyway, apologies, I shall go edit my post :D

Thanks for the replies on both sides. I'm definitely edging towards the dual RCD setup, purely because the huge difference in cost doesn't seem to provide value for money in terms of the benefit. If it was 10-20% more then sure, but almost 50% is a significant chunk and could almost certainly do more good elsewhere.

If I'm understanding it right, the only difference with dual RCD would, e.g. a socket downstairs causes it to trip, we'd lose the upstairs lights as well, and vice versa, whereas with individual RCBOs it would be just the downstairs sockets which went down?
 
Haggisman said:
If I'm understanding it right, the only difference with dual RCD would, e.g. a socket downstairs causes it to trip, we'd lose the upstairs lights as well, and vice versa, whereas with individual RCBOs it would be just the downstairs sockets which went down?
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Essentially yes, but it depends on the layout. If the downstairs sockets and upstairs lights are on the same RCD then a fault on the sockets would kill power to everything on that RCD including the upstairs lights. Circuits hanging off the other RCD woiuld not be affected so if the upstairs lights and downstairs sockets were on different RCDs then a fault on the downstairs sockets wouldn't impact the upstairs lights.
 
the-evaluator said:
Essentially yes, but it depends on the layout. If the downstairs sockets and upstairs lights are on the same RCD then a fault on the sockets would kill power to everything on that RCD including the upstairs lights. Circuits hanging off the other RCD woiuld not be affected so if the upstairs lights and downstairs sockets were on different RCDs then a fault on the downstairs sockets wouldn't impact the upstairs lights.
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Cool, thanks - the electrician said he would set it up so we'd always have either sockets or lights both up and down, so we could e.g. plug in a lamp or so for some light
 
I have no idea what type ours is, but it's reasonably modern.

It has about 7 circuits on separate RCDs, ones for upstairs lights, another downstairs, same for sockets, oven, electric underfloor heating etc, all on separate RCDs.

It's really sensitive also, as I've found out over the years doesn't take much to trip it, I joke that you'd struggle to intentionally electrocute yourself.

The other thing to factor in, is a big percentage of that cost will be the electrician's time and certificates.
 
BUDFORCE said:
I have no idea what type ours is, but it's reasonably modern.

It has about 7 circuits on separate RCDs, ones for upstairs lights, another downstairs, same for sockets, oven, electric underfloor heating etc, all on separate RCDs.

It's really sensitive also, as I've found out over the years doesn't take much to trip it, I joke that you'd struggle to intentionally electrocute yourself.

The other thing to factor in, is a big percentage of that cost will be the electrician's time and certificates.
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I doubt that's that many RCD's, I think you may be mistaking RCD's for MCB's.

RCD = Residual Current Device, it looks for fault current coming down the earth wire and if it exceeds a certain amount (usually 30mA) it'll drop and cut off the power.

MCB = Miniature Circuit Breaker, provides over current protection so if you have a 20A radial circuit and a device on that circuit tries to draw > 20A, the MCB will trip.
 
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