type c mcb on domestic hager board

[Simon Torr]

hi all,

Domestic installation question

I have an Hager split board, left hand controlled by an RCD.
100 A Main switch
RCD 63a, with upstairs and downstairs sockets 32a, 1 x 16a sockets all type C, there is also 1 x type B 20a MTN 120 for sockets.

The type B has two T&E cables, both ending in the garage for sockets. One cable enters the board via the back of the board, and the other disappears behind the mounting plate for the meeter. I'm not to know why there are two cables, but they there.

The reason for my question. I'm installing garage lights and socket via 63a board 20a and 6a, SWA 2.5 twin and earth .5 meter from main board

The 17th edition states that the board and mainly sockets and lighting should be split (down stair sockets and upstairs lights on one side of the board, and the opposite on the other side of the board). Alas

My question is why all the type C MCB's, From my understand type C characteristics is time delay.
Shouldn't type B be the preferred MCB or am I missing the plot, as the house is the normal two up two down.

:59:

 

[Darkwood]

As long as the install complies with the Zs values it doesn't really matter as it will still meet tripping time requirements unless you have Zs issues wouldn't concern yourself with it, ....who knows why the previous 'Electrician?' fitted type C we can only ponder all day as domestically I see little advantage.

 

[alanl]

Why do you think there are C type CB's used?
Large start up loads?
Or whatever was in the back of the van?
Have you calculated, or measured the Zs of the circuits?
Do they comply?

If you are adding new circuits, maybe time to fit another RCD, or take the new circuit off a RCBO?

 

[MDJ]

hi all,

Domestic installation question

I have an Hager split board, left hand controlled by an RCD.
100 A Main switch
RCD 63a, with upstairs and downstairs sockets 32a, 1 x 16a sockets all type C, there is also 1 x type B 20a MTN 120 for sockets.

The type B has two T&E cables, both ending in the garage for sockets. One cable enters the board via the back of the board, and the other disappears behind the mounting plate for the meeter. I'm not to know why there are two cables, but they there.

The reason for my question. I'm installing garage lights and socket via 63a board 20a and 6a, SWA 2.5 twin and earth .5 meter from main board

The 17th edition states that the board and mainly sockets and lighting should be split (down stair sockets and upstairs lights on one side of the board, and the opposite on the other side of the board). Alas

My question is why all the type C MCB's, From my understand type C characteristics is time delay.
Shouldn't type B be the preferred MCB or am I missing the plot, as the house is the normal two up two down.

:59:

Um no, however as Darkwood

 

[Darkwood]

hi all,

Domestic installation question

I have an Hager split board, left hand controlled by an RCD.
100 A Main switch
RCD 63a, with upstairs and downstairs sockets 32a, 1 x 16a sockets all type C, there is also 1 x type B 20a MTN 120 for sockets.

The type B has two T&E cables, both ending in the garage for sockets. One cable enters the board via the back of the board, and the other disappears behind the mounting plate for the meeter. I'm not to know why there are two cables, but they there.

The reason for my question. I'm installing garage lights and socket via 63a board 20a and 6a, SWA 2.5 twin and earth .5 meter from main board

The 17th edition states that the board and mainly sockets and lighting should be split (down stair sockets and upstairs lights on one side of the board, and the opposite on the other side of the board). Alas

My question is why all the type C MCB's, From my understand type C characteristics is time delay.
Shouldn't type B be the preferred MCB or am I missing the plot, as the house is the normal two up two down.

:59:

Missed that question... you are kind of there but not correct... its inrush allowance , however in a short circuit of little impedance the current will be so high that the type of the mcb is irrelevant.

 

[applemac]

I've seen a few type c rcbos last week going for about £3.50 bet there be all over the place soon

 

[Deleted member 9648]

Why do people panic if anything other than a type B is fitted? lol.
One good reason to fit type C's in a domestic situation is to prevent or at least reduce the risk of lamp failure on lighting circuits popping a type B,which is very common. In situations where less able or elderly people live much more attention should be paid to this,and yet you rarely see type C's fitted to lighting circuits