Extra consumer unit

I want to put a second consumer unit in. I have an rcd between the meter and the existing consumer unit. Am I ok to simply run 16mm cable from the rcd to the new consumer unit?

Thanks in advance.

There is no simple answer to your question. First it depends on the existing load on the suppliers feed, next the layout from the meter to the existing unit has on RCD and this will influence the decision, finally you don't say what kind of load you intend to put onto the new consumer unit. Domestic premises are usually supplied with a max load of 100amps so to be safe look at your existing consumer unit and add up the amperage of the various MCB/fuses. For instance, if you have two ringmains, that might add up to 60 amps 2x30amp fuses/mcb's, a cooker might add another 45 amps, lighting if seperately fused for two levels might add up to another 10 amps. Electricians would calculate for diversity and with this allowance would the demand would probably add up to a system well within it's allowances. If you don't have access to this kind of info/calculations or you're in doubt, I would suggest you don't attempt this until you have had a qualified electrician look at it. With respect this is not the kind of thing that you should attempt unless you have qualified guidance on hand.

Thanks loftus75.

I can do the calcs, but I am assuming that if I overload, because everything is on at the same time, then my system will trip before the supply fuse.

What size fuse is the supply company likely to put in for me to increase useable load.

This can't be a difficult problem because lots of houses these days have cookers, immersion heaters, lights, sockets, more than one electric shower, external lights etc.

My main point was really whether connecting through the rcd is any different to putting in a bakerlite connector.

Please let me have your thoughts.

Hello

What is the actual requirement? I suspect you have simply run out of circuits? In this case I would recomend replacing the consumer unit with a larger new one, perhaps taking the opportunity to put in something more flexible like a split load unit if not already in place, and if you understand the implications. In my humble opinion, this is more elegant than a second consumer unit.

Depends entirely of course on what you're trying to achieve. If you have done the sums and reckon you're going to draw more than 100A, as your second posting implies, then yes you're going to need input from your supplier. If not, then you're fortunate in being able to isolate your consumer unit since it looks like you have a 100A DP switch / RCD between it and the suppliers feed.

OF COURSE if this is not the case then please disregard all the above and get someone in.

Even if this is the case, as loftus says, don't proceed unless you're 100% comfortable with doing so. Installing a new consumer unit is not rocket science but deserves the utmost respect. Quality of connections, layout of cable runs etc can have unexpected implications as can be seen from a posting here last week about a faulty MCB quite possibly caused by loose connections.