Consumer Unit

Geof_t · Posted: Fri Apr 30, 2004 10:05 am Post Subject: Consumer Unit

Hi, i am looking to replace my old consumer unit with a modern unit, can someone tell me what size trip each typical circuit in a house requires?

securespark · Posted: Fri Apr 30, 2004 12:13 pm Post Subject:

Geoff

What have you got at the moment, in rthe way of circuits/fuses?

You seem very unsure about this topic.

plugwash · Posted: Fri Apr 30, 2004 4:14 pm Post Subject:

lights-6A
rings-32A
single socket cuircuits 16A
2.5mm radials-20A
4mm radials 32A
high power fixed appliances (cookers showers etc) breaker and cable sized to appliances demands

Geof_t · Posted: Sat May 01, 2004 8:40 am Post Subject: Consumer Unit

My original wiring was a complete joke, i cannot even begin to say how unsafe it was, but anyway i have completely rewired the house and am now ready to install a consumer unit. my current wiring system is as follows:

2 x 5amp lighting circuits (upstairs & downstairs)
3 x 16amp power circuits (upstairs, downstairs with the kitchen on its own circuit)
1 x 5amp lighting circuit for the external lights
1 x 30amp circuit for the cooker

ZenStalinist · Posted: Sat May 01, 2004 8:51 am Post Subject:

16 amp power circuit? I assume you refer to sockets here... Why not extend it into a 32 amp ringmain?

16 amp is low enough to be easily overloaded, and this will happen in the kitchen if you have, say, the washing machine and the kettle running at the same time. With the existing 2.5 mm wire, it is almost certain that the kitchen's rating could be uprated to 20 amps. That should solve some problems there, as for the others, I reccomend you extend them back to the consumer unit in a ring fashion and uprate to 32 amps.

Geof_t · Posted: Sat May 01, 2004 9:18 am Post Subject: consumer unit

i havent got a problem with the wiring, i am just trying to determine what mcb's i should use in place of the fuse.
the power circuits are ring circuits, and i have a choice of either 20 or 32 amp mcbs. doing my sums a 20 amp should be sufficient.

I have been looking at some deals on consumer units, and only have one concern, what type mcb to go for, type B or C?

i know that many people have problems with type B on light circuits.

What is the difference between the two?

ZenStalinist · Posted: Sat May 01, 2004 10:53 am Post Subject:

In domestic installations you should just about always use a type B MCB.

As the circuits are ring mains, they should be 32 amp MCBs.
The difference in MCB types is sensitivity.

On our lighting circuit we have type B, and don't have problems per se, ´though it does trip sometimes if an incandescent bulb blows, which can be a bit annoying. Overall though, I still reccomend type B.

If you use an RCD CU (strongly reccomended), then you ought to have anything outside on the RCD circuit (required), sockets (reccomended). On the non-RCD side you should have your lighting, and debatably the cooker, etc (some prefer them on the RCD side, but some models of oven can cause nuiscence tripping.)