John Rumm wrote:
Richard wrote:

Hmm. My place has an 80mA RCD protecting the 13A sockets. It's a
standalone RCD feeding the CU which contains only a double pole 100A
isolator. Is that (still) acceptible?

It is probably a 30mA trip RCD with 80A switching capacity. If that is
the only CU, then no it is not an acceptable solution these days, since
one fault loses you all power and lights.

Lecky board raised no eyebrows and, in fact re-located it to a more
convenient location relative to the new CUs that were subsequently
installed, when installing my dual rate meter 8 years ago.

They would be unlikely to comment since it is a common arrangement, and
for a time (15th edition) was considered an appropriate way of doing
things. (since it was (rightly) believed that the RCD would result in a
reduction of serious electric shock accidents, but the consequences of
plunging a house into darkness unexpectedly had not been understood).

I suspect it is more to do with 'reasonable' cost. When the 15th regs
were being prepared (and these things take time to be approved and
issued) the RCD was an expensive device. To require people to have 2 or
3 was probably not reasonable, and losing all the lights was compared to
electrocution. However they are so cheap that by the time the next regs
come out they will probably require 2 for lights and 2 or 3 for
everything else - just my guess