Additional consumer unit in domestic property breaker sizes?

[P-Courty]

I have a few questions about a couple of breaker sizes needed due to current draw and diversity.

In place already is as usual;
A main service fuse (100A)
25mm P&N tails to meter
25mm P&N tails from meter to CU
12 way CU split load

What has been done is a garage conversion to kitchen.
I was told they wanted a new CU for the kitchen area due to the 12 way being full and old (and strapped for cash).

I've been given a 6 way CU with 80A RCD, P&N 25mm tails & 16mm earth tail (customer supplied).

My plan was (correct me if I am wrong anywhere please) going to need additional items to complete.

1. Outgoing 25mm tails from meter to a 2 way CU with an MK 100A double pole main breaker (to protect service fuse).
2. From there 25mm tails to a 6 terminal henley block.
3. From the henley block 25mm tails to new 6 way CU and 25mm tails to existing CU.
4. 16mm earth to each CU from MEB.

Now this is were I could do with a little help on breakers.

The new board only has the RCD, do I need a main breaker in there? As in an 80A main and 63A 30mA RCD?
The circuits put it are a 32A kitchen ring final and a cooker circuit (for some reason in a 2.5mm t&e) I did question that and they said the kitchen fitters said the 2 single ovens are capable of being on 16A radials and the hob (not heard that before) so I may need to upgrade the cable size for that when I find out the kw of them (think it will be a must). This is what is confusing me on the RCD and main breaker sizes I should choose as i'm not completely sure what the draw is going to be.

Any help on all of this would be very much appreciated as they want this completed by the end of this week.

Thank you in advance for any help and advice given.

 

[Octopus]

Hold on. Who's designing this? You or kev the kitchen fitter?

 

[TJ Anderson]

Read your OSG mate for cooker diversity. You can put 15KW of cooking load on 32A circuit if that helps you. Not sure where you are going with a main breaker to protect service fuse......

 

[davesparks]

MK do not make 100A double pole circuit breakers.

In this country we don't fit main breakers in CU's

I shouldn't worry about the kitchen wiring too much, whoever has installed it will be connecting it and signing it off.
You obviously won't be doing this as only the person who installed it can do the sign off or LABC.

 

[Guest55]

the "main breaker" is just a double pole switch . it has no over current tripping ability.

i think thats where youre getting confused

 

[trev]

You're not an electrician are you?

 

[P-Courty]

the "main breaker" is just a double pole switch . it has no over current tripping ability.

i think thats where youre getting confused

Sorry I was thinking too much in my head then I ment the 100A breaker for the isolation of the 2 CU's.

 

[davesparks]

Sorry I was thinking too much in my head then I ment the 100A breaker for the isolation of the 2 CU's.

You've still not got it then!

You don't use a breaker in that situation

 

[Rockingit]

You're not an electrician are you?

No, he's a Electrical Trainee [emoji13] !!!

 

[P-Courty]

Hold on. Who's designing this? You or kev the kitchen fitter?

The circuits are already in and the client done what the kitchen fitter told him and put 2.5mm in (looks like i'll be changing that).

I did ask for the ratings off the client but all he would tell me is " the kitchen fitter said they can go on 16A 2.5mm radials" (he's one of those people who say your wrong because someone older than you has told them different)

So all I have now been asked to do is put this board on so for obvious reasons I want to make sure that the RCD and main breakers are correct and adequate for the protect of the circuits.

 

[trev]

Mate, if you're not an electrician then you need to get one.
If you are then you need to start acting like one.

 

[P-Courty]

You've still not got it then!

You don't use a breaker in that situation

So you would take the 25mm tails straight from the meter to a henley block then to the individual boards with no other isolation than only the main service fuse?

 

[davesparks]

The circuits are already in and the client done what the kitchen fitter told him and put 2.5mm in (looks like i'll be changing that).

I did ask for the ratings off the client but all he would tell me is " the kitchen fitter said they can go on 16A 2.5mm radials" (he's one of those people who say your wrong because someone older than you has told them different)

So all I have now been asked to do is put this board on so for obvious reasons I want to make sure that the RCD and main breakers are correct and adequate for the protect of the circuits.

If you did not install the circuits then you do not connect and test them, it's pretty simple.

In domestics the design, installation and IV is done by the same person who then signs it off. There is no scope for anyone else to sign off other than LABC


I'll say it again, we don't fit main breakers in CUs nor would it be necessary or appropriate.
You also need to ensure bonding and everything else is up to scratch before starting on any such works

 

[P-Courty]

Mate, if you're not an electrician then you need to get one.
If you are then you need to start acting like one.

Now that's a bit aggressive isn't it I am only trying to ask what I thought was a friendly community of electricians for advice I'm sure back when you started as an electrician you used to ask questions and hope people would be helpful to you too sorry if I've some how touched à nerve but I am only asking for help and guidance

 

[davesparks]

So you would take the 25mm tails straight from the meter to a henley block then to the individual boards with no other isolation than only the main service fuse?

No I wouldn't, the service fuse is not there as a point of isolation for the installation. Hence why it is sealed and we are not allowed to remove it!

I would install a main switch as required by the regulations and wouldn't use a Henley block if I could help it.
But then I wouldn't be doing a job which involved connecting up a DIYers bodgery

 

[P-Courty]

I have checked all equipotential bonding is in place and back to the MEB the circuits aren't going to be connected by me i'm just putting the board on from the main supply that is all i have been asked to do.

 

[davesparks]

Now that's a bit aggressive isn't it I am only trying to ask what I thought was a friendly community of electricians for advice I'm sure back when you started as an electrician you used to ask questions and hope people would be helpful to you too sorry if I've some how touched à nerve but I am only asking for help and guidance

Are you an electrician?

Trev and I and most people here qualified through an apprenticeship where we were taught all of this.

 

[P-Courty]

No I wouldn't, the service fuse is not there as a point of isolation for the installation. Hence why it is sealed and we are not allowed to remove it!

I would install a main switch as required by the regulations and wouldn't use a Henley block if I could help it.
But then I wouldn't be doing a job which involved connecting up a DIYers bodgery

So you would put a main switch between the meter and henley block? Thats what i was on about ...

 

[trev]

Mate, when I started out I was closely supervised by a properly qualified man who only ever let me do things when he was convinced I had the ability to do them.
I'm happy to help people but your questions show a lack of training to me. If I'm wrong then I'll apologise and help as much as I can.
It isn't my intention to be aggressive but I'll clarify what I said , if you are going to be the electrician on this job then YOU have to take charge of it. YOU are the one (allegedly) with the training and expertise to do it correctly, not Kev the kitchen fitter. If necessary you tell him to go forth and multiply and stick to what he knows because you have a greater degree of expertise in electrical matters than him.
That's what I'd do anyway

 

[davesparks]

So you would put a main switch between the meter and henley block? Thats what i was on about ...

No it wasn't, you were talking about a breaker not a switch, they are two different and distinct things.