Electrical conundrum

Sep 16, 2006 6 Replies

just moved house, looking at the consumer unit - wylex split load 80A rcd



100A isolator looks newish. Says on the front 'for all circuits total load not to exceed switch rating', in the unit there are the following mcbs

non rcd



40A cooker radial
16A heating/boiler radial
6A upstairs lighting
6A downstairs lighting
6A Smoke alarms

rcd



32A west ring
32A east ring
32A garage ring - thought I'd derate to 16 since can only use dust collector + one tool at a time
32A kitchen ring - fixed appliances (washing mc, tumble dryer, dishwasher waste disposal unit
6A garage/external lighting

total 206A ummm Diversity - in that case why the label



Had a look at screwfix, found the consumer unit with preinstalled mcb's



1x40,2x16, 4x32, 3x6 total 216A

do they do 200a isolators then?? if not why so many mcbs.



I'm not particularly worried since at the moment incoming 16mm2 tails + 60A main fuse hopefully soon to be uprated.



Largest supply i've heard about is 125A new builds so do you get 125A isolators or do you put 2 isolators in one box or what.



Any comments on the distribution of mcbs above and why the label, anybody here total mcb's less that isolator value


It says total _load_, not total value of all the MCBs. Unless you somehow manage to fully load all the circuits, the two values are going to be substantially different.

Max for a single phase supply is normally 100A. If you want any more, you usually have to get a 3-phase supply.

Because the isolator and bus bars are rated for 100A max.

As you surmise, diversity may be applied on consumer units.

Unlikely, because you are very unlikely to get a domestic single-phase supply of more than 100A.

To divide the installation into an adequate number of individual circuits

You'd either use a higher rated consumer unit, or split the installation between two consumer units (eg a separate one for storage heating)

Owain

Looks OK lighting is pre the RCD. Though I'd rather the garage lighting was as well but as that also feeds external stuff it has to have an RCD.

Read what the label actually says not what you think it says.

RECTAL LICE is the best I can come up with I'm afraid.

-Kevin.

The message from "Gunther Gloop" contains these words:

Later, cecil.

CLERICAL or LAETRILE or ERECT LILAC

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