ARW wrote:

On 06/02/2019 12:58, Roger Hayter wrote:
I have an economy seven supply. Two 25mm wires go from the main fuse
block to the meter (presumably live and neutral) and then to a switch
and then to two Henley blocks. From one of these a 25mm wire goes to a
radio controlled switch, and out of this time switch another 25mm wire
goes to a third Henley block. The house supply runs from the first two
blocks, and a separate wire from the third block presumably supplies
live to the night time only supply.


However, there are two 10mm wires from the main fuse block to the radio
switch, and one 6mm wire joins the radio switch to the meter.

Can I assume that none of the Henley blocks is live when the main fuse
is open? In theory any one of the last three wires by-passes the main
switch and could internally connect the night time supply to the live
via the radio switch box. And theoretically could back feed the main
house CUs via the live in connection to the radio switch. Is it safe
to assume with a high degree of reliablity that the internal
construction of the radio switch is such as to make this impossible?

(Obviously I wouldn't work on anything without checking it is not live,
but the radio switch is, after all, a switch and if it could connect
live to the wrong wiring could presumably do it suddenly and
unexpectedly.)




With the main fuse out everything should be dead.

True, but I only want to change an MCB for an RCBO in the economy 7 CU
and would prefer to rely on the main switch if it isafe to do so.
Removing the main fuse is potentially hazardous, isn't it?

--

Roger Hayter