MCB &RCD's

[MegPas]

Could you please advise which circuits you would normally hace RCD protection on in a CU

13A sockets
Lighting
Cooker (with 13A socket)
Shower 9.8Kw
immersion heater

Also if possible what sort of MCB ratings would be on each.

Just had some electrical work done including a new CU fitted & some of the things the sparky has done concerns me so will appreciate anybodies help.

I know other factors come into it, including which the wind is blowing and I could pay to have an inspector come. So please dont go all to industry polotical on me

 

[davy_owen_88]

13A sockets - RCD protected - 32A
Lighting - not RCD protected - 6A
Cooker (with 13A socket) - not RCD protected - depends on how powerful the cooker is.
Shower 9.8Kw - RCD protected - 45A
immersion heater - not RCD protected - 16A

If you are on a TT supply then you should have a time delayed 100mA RCD protecting everything and a 30mA protecting the ones noted above.

Was the electrician a member of a self-certification scheme? Did give you an certificates?

Davy

 

[MegPas]

work is ongoing so certs are to follow.

Sorry to be a pain but what do you mean by a TT supply?

 

[davy_owen_88]

A type of earthing arrangement that relies on a copper rod buried into the ground to make contact.

 

[MegPas]

earth is bonded to the sheath of the incoming supply so I assume not a TT supply. Does this change things?

 

[davy_owen_88]

Then that' not a TT supply and means you don't need the time delayed 100mA RCD.

Davy

 

[MegPas]

One last thing

The cooker supply is 5900W, so the MCB would be?
& as there is a 13A socket on it should that not be RCD protected?


With thanks for the advise, a great help.

 

[davy_owen_88]

That would require a 32A MCB if rated for full load. If diversity is applied:
5900W/230V = 25.7A

10A + 30% of remaining + 5A for socket = 10A + 5A + 5A = 20A MCB

Regarding the RCD protection... Cookers tend to have a fair amount of earth leakage during normal use which could cause nuisance tripping of the RCD. There are 3 options:

1) Put it on the RCD side and hope your lucky enough not to experience the nuisance tripping
2) Don't have a socket at the cooker switch and put it on the non-RCD side.
3) Mark the socket as 'Not suitable for supplying equipment outdoors' and put it on the non-RCD side.

Davy

 

[Jaymack]

13A sockets - RCD protected - 32A
Cooker (with 13A socket) - not RCD protected - depends on how powerful the cooker is. Davy

Powerful? What means this? RCD required, see regs 471-08 and 471-16.

Shower 9.8Kw - RCD protected - 45A.
Davy

Not required to the regulations, although some suppliers require it, installer's option whether to install or not. (CYA by suppliers).

Jaymack

 

[davy_owen_88]

13A sockets - RCD protected - 32A
Cooker (with 13A socket) - not RCD protected - depends on how powerful the cooker is. Davy

Powerful? What means this? RCD required, see regs 471-08 and 471-16.

Read my other post regarding RCD protection for the cooker. Powerful as in it's power rating... a deciding factor in MCB selection.

Shower 9.8Kw - RCD protected - 45A.
Davy

Not required to the regulations, although some suppliers require it, installer's option whether to install or not. (CYA by suppliers).

Jaymack

But it is good practice to put showers on the RCD side.