CU

[saleem]

I have bought new MEM CU 7+7 configurable split load.In my house two separate teams of sparks are working.One is involved in loft conversion who is going to fit main board as well.Both sparks have different opinion on what should be on rcd protection side and what should,nt.For that reason i am posting this question on forum to have expert openion.Myhouse has three floors including G floor.Wiring layout is something like this.
GROUND FLOOR
LIGHTING 6amp
G FLOOR RING 32 amp
KITCHEN RING 32amp
KITCHEN COOKER RADIAL 32amp
SECOND FLOOR RING 32amp
SECOND FLOOR LIGHTING 6amp
THIRD FLOOR RING 32amp
THIRD FLOOR LIGHTING 6amp
SHOWER 50amp
GARAGE 32amp
What should need rcd protection and what should be on other side.I know G floor ring,garage and shower probabaly need RCD protection.Do other rings need RCD proction.

 

[Taylortwocities]

Yes G floor ring,garage and shower need RCD protection. Also cooker radial if the cooker switch has an 'adopted' socket on it.

Other rings only need RCD protection if they could be used to power potrtable equipment outdoors.

Personally, if I had a house with kids in it then i would have all the sockets on RCD.

 

[davy_owen_88]

Only sockets that can reasonably be expected to supply outdoor equipment require RCD protection, but personally, I think all socket circuits should be RCD protected, along with showers and certain appliances within certain zones in the bathroom.

Keep lighting on the non-RCD side, and also the cooker radial (make sure there isn't a socket on the cooker switch)

EDIT: Too slow

 

[ricicle]

Although regulations state that socket outlets that can be expected to supply portable equipment outdoors should be protected by a 30mA rcd, most sparkies, including myself, will protect ALL sockets with it.
And of course most manufacturers stipulate their showers are protected by a 30mA RCD as well!

EDIT: Too, too slow

 

[photon]

using an RCBO on the non RCD side for other (upstairs) sockets and another for lighting is a good way to provide whole house protection without the problems associated with nuisance tripping if all are on the RCD side of the split board.
Costs a little more but what price do you place on your families safety

 

[saleem]

using an RCBO on the non RCD side for other (upstairs) sockets and another for lighting is a good way to provide whole house protection without the problems associated with nuisance tripping if all are on the RCD side of the split board.
Costs a little more but what price do you place on your families safety

Do we need separate RCBO for every curcuit on non rcd side.I have three lighting,one cooker radial on non rcd side .All other are on rcd side.If two upstairs rings are taken to non rcd side does it mean i need 5 rcbo,s.

 

[saleem]

Although regulations state that socket outlets that can be expected to supply portable equipment outdoors should be protected by a 30mA rcd, most sparkies, including myself, will protect ALL sockets with it.
And of course most manufacturers stipulate their showers are protected by a 30mA RCD as well!

EDIT: Too, too slow

As photon mentioned if all are on rcd side except lighting,cooker radial,is there a risk of nuisance tripping.

 

[saleem]

Yes G floor ring,garage and shower need RCD protection. Also cooker radial if the cooker switch has an 'adopted' socket on it.

Other rings only need RCD protection if they could be used to power potrtable equipment outdoors.

Personally, if I had a house with kids in it then i would have all the sockets on RCD.

If most are on RCD side as in my origenal question except lighting and cooker radial,would it cause problem, i mean tripping for no reason.

 

[Chri5]

Saleem

All circuits on the RCD rail will switch off if the RCD trips, so if you have 3 ring circuits on the RCD side all will go off if 1 circuit trips due to say a fault appliance being used.

This could be inconvient, if say the trip happens when your on hols and say the fridge / freeze, fish tank heater, alarm system etc also fail.

An RCBO controls only 1 circuit, so only kills that circuit on trip- an RCD controls how every many circuits are on that side and will trip all the circuits.

RCBO's are £35+ each, but do offer a great alternative to the "all the eggs in the same basket" situation.

It might be worth considering the IEE 17th ed (due 2008) which will require all circuit within a bathroom to be RCD / RCBO protected. This includes the light circuit in the bathrooms.

Problem is that it could be dangerous if all lights and socket circuits are on the RCD rail- One trip and nearly everything in the property will turn off, not good at 3am in total darkness attempting to find the CU and switch back on. So RCBO the lights, RCD the circuits suggested and the chance that both trip is all but removed.

If you do put the lights on RCBO or RCD to comply with 17th ed (although not essential) DONT have the smoke detectors on the light circuit, have them as an entirely separate circuit on the standard non RCD supply side.

 

[saleem]

Saleem

All circuits on the RCD rail will switch off if the RCD trips, so if you have 3 ring circuits on the RCD side all will go off if 1 circuit trips due to say a fault appliance being used.

This could be inconvient, if say the trip happens when your on hols and say the fridge / freeze, fish tank heater, alarm system etc also fail.

An RCBO controls only 1 circuit, so only kills that circuit on trip- an RCD controls how every many circuits are on that side and will trip all the circuits.

RCBO's are £35+ each, but do offer a great alternative to the "all the eggs in the same basket" situation.

It might be worth considering the IEE 17th ed (due 2008) which will require all circuit within a bathroom to be RCD / RCBO protected. This includes the light circuit in the bathrooms.

Problem is that it could be dangerous if all lights and socket circuits are on the RCD rail- One trip and nearly everything in the property will turn off, not good at 3am in total darkness attempting to find the CU and switch back on. So RCBO the lights, RCD the circuits suggested and the chance that both trip is all but removed.

If you do put the lights on RCBO or RCD to comply with 17th ed (although not essential) DONT have the smoke detectors on the light circuit, have them as an entirely separate circuit on the standard non RCD supply side.

Many thanks chris for much detailed answer.There are two sparks involved in my house.One is doing loft conversion into two bedrooms,bath room and computer room on top floor, also shower room on second floor and lighting as well.He also fitted MEM CU 2000 AD.Second one is doing entire ground floor,second floor ring main and garage.At the moment we have all lighting,cooker radial and 20amp spare mcb +2 blanks on non rcd side.RCD side has shower,garage,and ring s + few blanks.Is this arrangement ok.Another thing about RCBO is,are they put on rail same as mcb.I have seen some wires attached to it .Where are they connected.

 

[securespark]

He will know where to connect them, don't worry.

 

[ricicle]

He will know where to connect them, don't worry.

Doesn't sound like it, does it?

 

[securespark]

If the spark doesn't know how to wire an RCBO, he's not a proper spark...

 

[FredFlintstone]

If the spark doesn't know how to wire an RCBO, he's not a proper spark...

And will therefore be unable to certify the work for compliance purposes.

They link to the neutral and earth bars but if you're at all unsure about what you're doing, get someone to do it for you.

Regards

Fred