Circuit protection in CU

[Hugo329]

Hello

I currently have a consumer unit without any rcd's. It just has main switch and mcb's. I believe that I need rcd protection for at least the downstairs sockets, is this correct? Is there any other circuits that need RCD protection? Would I be able to use rcbo's instead of RCD's for the protect and meet the necessary regulations? Thanks.

 

[securespark]

Under the previous regs, socket outlets likely to be used to supply equipment for use outdoors required RCD protection.

Under the current regs, all circuits require RCD protection. If your board has RCBO's available for it, then they could be substituted. However, it is reportable work & an EIC should be produced too.

 

[Hugo329]

What would be the best way to do this then as getting an RCBO for each circuit would be quite expensive, are there more cost effective ways?

 

[kevindgas]

probably going to be cheaper in the long run to replace the board than fit RCBO's throughout, as the test required is virtually the same

 

[Chri5]

What would be the best way to do this then as getting an RCBO for each circuit would be quite expensive, are there more cost effective ways?

Dual RCD board would run to £140 + labour for a 10 circuit board with 10 x MCB's- say a days labour with full tests and paperwork write up.

RCBO's range from £25-£40 each, but are a 5 minute per circuit job + the testing.

RCBO's fit the requirement far better since they disconnect the same as an RCD but have only the fault circuit rather than a group of circuits on them.

Far less inconvenient for the user and by far the best way to comply with 17th requirements.

 

[ColJack]

depending on the board you already have you might be able to split it up and fit rcd's to it to make it a split load board..

 

[ericmark]

As with many electrical jobs there are many ways to comply with the regulations. However often by time one includes labour, materials, and LABC charges non are cheap.

So lets compare the single unit width RCBO with the multi-circuit RCD.
1) RCBO only switch the line which with a TN-C-S supply is fine but there are issues with a TT supply.
2) Using the same RCD for safety circuits and power circuits can present dangers and a risk assessment is really required to work out the likely hood and results should a RCD trip. Although it is considered that in the main if the sockets are not in same area as lights protected by a RCD it is OK. This is not always the case.
3) Auto resetting RCD's are very expensive around £250 and are not normally used in domestic installations.
4) Emergency lights are also expensive but there are some cheap options including re-chargeable torches which will light on power failure but the use of these in domestic is also in debate as the home owner can so easy disable the safety item without realizing what his actions could mean.
5) The use of Ali-tube cable and RCD sockets or Plugs is also subject to control problems and all too easy to be unintentionally disabled.
6) Mini consumer units although may be considered in same way as FCU's are rather uncertain as to if Part P covers them or not and as such hard to advise as to their use.

I is hard therefore to give any hard and fast advice on which way to proceed and only with a site visit can anyone advise as to best way forward. If there was no Part P I would change my duel RCD system for RCBO's but cost v advantage does not warrant change. However if I did not already have duel RCD I would fit RCBO

 

[Hugo329]

Thanks for all you comments.

So you say that all circuits needs RCD protection now, is that lighting, shower, sockets, everything?

The CU that is installed is a Volex one, do you know if it is possible to change these in splitload units?

 

[JohnD]

the rules have changed for new installations, so if you were building a new house you would be unlikely to have any circuits that did not have to go on an RCD

However an old house is not obliged to be rewired every time the rules change.

For safety, I would say at least the shower and sockets should be RCD protected.

How many circuits do you have, and how old is your consumer unit?

RCBOs are coming down in price as they get more popular.

 

[Hugo329]

I have 7 circuits:-

upstairs sockets
downstairs sockets
upstairs lights
downstairs lights
cooker
shower
garage (with goes to a garage cu)

the cu was installed about 5 years ago

 

[Hugo329]

I'll correct that last posting actually

I have 9 circuits:-

upstairs sockets
downstairs sockets
upstairs lights
downstairs lights
central heating controller
extra sockets on a radial
cooker
shower
garage (which goes to a garage cu that is RCD'd)

the cu was installed about 5 years ago

 

[ban-all-sheds]

I'll correct that last posting actually

.
.
.

 

[electronicsuk]

I have 7 circuits:-

upstairs sockets
downstairs sockets
upstairs lights
downstairs lights
cooker
shower
garage (with goes to a garage cu)

the cu was installed about 5 years ago

Are you sure the main switch isn't an RCD? An installation of that age should have had an RCD installed on the downstairs sockets as a minimum.

 

[Taylortwocities]

Hugo, I recently spent a horrible time putting in just two RCBOs into a Volex board. What should have taken 30 minutes took half a day.

The Volex board is, in my opinion, not designed to accomodate RCBOs, there's no head room and the existing main connect cables and busbars make it an almost impossible job.

If it were my decision, I'd bite the bullet and get a nice new QUALITY 17th edition consumer unit installed.

 

[Hugo329]

Thanks for the info on the Volex board.

Yes the main switch is just a main switch. I bought the house about 4 1/2 years ago and they said it had just been rewired.

Is it possible to add RCD's to the board and what sort of rating would I need? Would it have to be a split load with 2 RCD's or can it be done with just 1?