Socket behind dishwasher pt.2 - are we being had?

[deadshort]

Install the rcbo on the kitchen sockets

DS

 

[Iggifer]

the engineer would have to source a bus bar, that consumer unit is an old range, although possibly ok, it may not be compatible to take a current range busbar

The current Hager busbar is almost (if not completely) identical to the slightly older range. Hager themselves have confirmed backwards compatibility of all of the new range, with all of the old range. Indeed - if the guy fits an RCBO it's going to be from the current range I would suspect.

 

[flameport]

I guess we just want what is safe and cost effective.

All of the options are safe. They may work differently and have implications when things go wrong.

All socket outlets must have an RCD - your kitchen currently does not. Therefore an RCD must be fitted somewhere if this new socket is to be installed.

Option 1 is to fit a socket with the RCD built in. This is the cheapest, however is far from ideal as it still leaves the rest of the kitchen without an RCD.
In the event of any other sockets being added or moved, the same problem applies again.
Many RCD sockets are of the type where when the power fails, the button on the front must be pressed to switch the socket on again - very inconvenient when that socket is behind your dishwasher.

Option 2 is to change the circuit breaker for the kitchen sockets in the consumer unit to an RCBO, which is an RCD and circuit breaker combined in the same device.
This provides RCD protection to all of the kictchen sockets including the new, which would just be a normal one.
A possible problem there is that the whole kitchen circuit requires testing, and there may be some minor problems already existing which require fixing as part of that work. Hence it costs more.

Option 3 (which the electrician did not quote for) is to move the circuit breaker for the kitchen sockets onto the RCD side of the consumer unit. This achieves the same result as option 2, but with the added disadvantage that any fault on any socket in the house results in the entire lot having no power. This can also occur with a large number of appliances plugged in, as many have a tiny amount of leakage to earth as part of their design. With the entire house on a single RCD, such problems are far more likely.
This does not comply either because of :

314.1 Every installation shall be divided into circuits as necessary to:
i. avoid danger and minimize inconvenience in the event of a fault
....
iv. reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents not due to a fault​

Therefore
Option 1 is the cheapest, being the absolute minimum required.
Option 2 is better, but costs more.
Option 3 is not compliant and that is probably why the electrician did not mention or quote for it.

 

[ban-all-sheds]

That could be done, but would put all of the sockets in the property on a single RCD, and could in no way be considered to comply with section 314.

Of course it could, as long as the consequences of RCD operation are considered.

I agree, it is not ideal, but I am suspicious of an electrician who doesn't offer it up as a solution to be considered, pros'n'cons weighed etc, but only offers solutions with a higher price tag attached.

 

[ban-all-sheds]

Ban all sheds option could become more time consuming. IF the bus bar has been cut, the engineer would have to source a bus bar, that consumer unit is an old range, although possibly ok, it may not be compatible to take a current range busbar.

Really?

Really?

You honestly think that someone would have cut the busbar away around here:

?

Why would they do that?

 

[ban-all-sheds]

I would not particularly want (and do not have) an RCD on the kitchen circuit but that is not now allowed when new work is done.

It's perfectly do-able.

It takes more work when installing, and more will, but if someone wants it that way they can have it.

OOI -why do you not particularly want an RCD on the kitchen circuit?

 

[ban-all-sheds]

All socket outlets must have an RCD

Untrue. Read 411.3.3 Exception (b).

Option 3 (which the electrician did not quote for) is to move the circuit breaker for the kitchen sockets onto the RCD side of the consumer unit. This achieves the same result as option 2, but with the added disadvantage that any fault on any socket in the house results in the entire lot having no power. This can also occur with a large number of appliances plugged in, as many have a tiny amount of leakage to earth as part of their design. With the entire house on a single RCD, such problems are far more likely.
This does not comply either because of :

314.1 Every installation shall be divided into circuits as necessary to:
i. avoid danger and minimize inconvenience in the event of a fault​

A value judgement which should be the topic of a discussion with the customer. I'll bet there are still loads of flats being built with just 1 RCD in the CU. And I wasn't suggesting putting the whole house on the same RCD.

​

....
iv. reduce the possibility of unwanted tripping of RCDs due to excessive protective conductor currents not due to a fault

How many kitchen appliances do that?

Option 3 is not compliant.

I disagree. It could be.

 

[Klang180]

Thanks everyone, i have a lot of going back through this post to make sure ample likes are dished out!

I think in the end I was perhaps being a cheapskate and the RCBO option is the best. I agree that having an RCD behind the DW cold be a real pain in the proverbial so maybe it isn't worth the compromise.

You've all been so helpful on this one and contributed to quite the discussion, i've learnt a lot, not least there is no one way to do anything even in the world of electrics or should that be especially in the world of home electrics?

Thanks to everyone.

 

[EFLImpudence]

OOI -why do you not particularly want an RCD on the kitchen circuit?

I just think the blanket demand for RCDs is OTT and unwarranted.
The OP's case being a good example of this.

Therefore, there should, IMO, be a case of more appropriate determination whether an RCD should be fitted.

As for my kitchen, I just don't want any tripping because of slightly worn elements or similar things.

An RCBO would be better than an RCCB which, at least, would not result in everything being disconnected by a lamp blowing or equally trivial occurrence.

 

[ban-all-sheds]

I just think the blanket demand for RCDs is OTT and unwarranted.
The OP's case being a good example of this.

Therefore, there should, IMO, be a case of more appropriate determination whether an RCD should be fitted.

What criteria do you think should be used to determine if an RCD should be installed?

As for my kitchen, I just don't want any tripping because of slightly worn elements or similar things.

What voltage would you be happy to see exposed conductive parts reach because of slightly worn elements?

 

[JohnW2]

I just think the blanket demand for RCDs is OTT and unwarranted. The OP's case being a good example of this.

Whatever one thinks about RCDs, it is seemingly a bit odd to require RCD protection of just one (new) socket on a circuit, whilst all the others on the same circuit remain without such protection.

However, it's far from easy to work out how else the introduction of 'new requirements' could be managed. A retrospective requirement for all the sockets on existing circuits to be RCD-protected if one new socket was added would probably be strongly opposed.

... and all that, of course, in addition to the general question of whether, in practice, RCDs actually provide sufficient 'benefit' for them to be compulsory in any situation - but that's a totally different discussion!

Kind Regards, John

 

[JohnW2]

What voltage would you be happy to see exposed conductive parts reach because of slightly worn elements?

With a typical earth component of the EFLI, the current required to raise the voltage of exposed-c-ps to a worrying level would normally be umpteen times the In of the circuit's OPD wouldn't it?

Kind Regards, John

 

[ban-all-sheds]

Whatever one thinks about RCDs, it is seemingly a bit odd to require RCD protection of just one (new) socket on a circuit, whilst all the others on the same circuit remain without such protection.

That's how changes in practices happen...

 

[JohnW2]

That's how changes in practices happen...

It usually is, but there is no reason why there can't be 'transitional provisions' - e.g. in this case only to require RCD protection of new sockets on an existing circuit if the result would be that the proportion of RCD-protected sockets on the circuits exceeded some specified level, or something like that.

Kind Regards, John

 

[ban-all-sheds]

Then all the refuseniks would simply add sockets "one at a time", and there would never be more than 1 new socket at any point.