by ericmark »
Tue Sep 15, 2015 9:26 am
You say "Best" so the appendix to regulations says that fixed items, and because of weight those items are considered as fixed, over 2kW and likely both are over 2kW should have a dedicated circuit.
Now in practice this is rare, However consideration should be given to loads already on the 32A ring. Where the ring only feeds the kitchen it's unlikely to be a problem, but (never worked out why laundry and cooking should be mixed) washing machine, tumble drier, oven, dishwasher are all found in the kitchen, If this load is central on a ring again normally not a problem but where this is close to the consumer unit it can result in an overload on one leg of the ring.
Time is a major factor, cables take time to over heat which is why we don't worry about the kettle. Two major loads in a house other than shower and hob which are always on a dedicated supply is the immersion heater and tumble drier. This would include a washer/drier.
In spite of a load of 2kW to 3kW with non drier washing machine, dish washer, and oven they do not run for that long on high power, once water is heated or oven temperature is reached they stop using high power.
So step one is consider what is on the ring and is this likely to be a problem? Clearly you don't want to do work which then needs re-doing so consider this first.
Next is control. In the old days washing machines had weights and some times these came loose. I have seen this happen and it can destroy a kitchen and the washing machine moves so violently you can't get near to switch it off. So it was common to have a remote switch. Today washers have out of balance sensors which should the weights become loose switch off the machine so this is not so much of a problem any more.
However the idea of having a grid switch which controls hidden sockets for fridge, freezer, washer, dish washer, drier etc is still popular and you can get the switches with names engraved on them. Look up "Grid Switch".
Also in the grid switch range you can get fuse holders, sockets, TV outlets, and computer outlets, even USB chargers so you can build the panel with what you want. Switches normally rated 20A so only a single socket off each switch unless fused.
You can also get fused connection units (FCU) which often has a switch.
One of the problems with RCD protection is the neutral - earth fault which can cause the RCD to trip even when the item is switched off. Having double pole switches for items where you can't reach the plug really helps work out what is causing the RCD to trip. As a result I would always fit switched FCU so it's easier to locate a fault where RCD trips.
So main thing is how easy to reach the plug? It is all too common for a bit of toast stuck in toaster to cause the RCD to trip when the kettle is used. So being able to switch off with ease is important even if normally you leave them all on like I do.
Note grid switch can be single or double pole, for help when RCD trips it needs to be double.
If you don't have RCD protection then there is little option, all new sockets must be RCD protected and to get to the reset button behind an appliance every time you get a power cut is not fun. So RCD FCU would be the way to go. Using active RCD means it trips with a power cut likely good for washing machine as you then know it has stopped mid cycle. Not so good for the Freezer where you want a passive RCD so it does not trip with a power cut.
In Wales you would need to register work with LABC but not in England, so in Wales cheaper to use a scheme member electrician. Unless your not worried about breaking the law of course. Don't know Scottish and Irish rules.
