Bit of advice on wiring of an electric shower

[DetlefSchmitz]

A number of posters on this forum seem to be very critical of neon scewdrivers, and recommend multimeters, but do not mention that multimeters also have a high input impedance and will record sigificant voltages when connected to wiring which is isolated from a source voltage. Such as wires from a switched off FCU.

They forget that electrians' voltage measuring instruments usually incorporate resistive loads between their terminals sufficient to pull these stray voltages down to close to zero.

A multimeter used in this application is quite likely to show a voltage, though less than 230V ac. This should not, in itself, be cause for concern. The cpc in the cable may have sufficient capacitive coupling to reduce this voltage to nearly zero, or it may not.

 

[seasickstevie]

45amp switches have a load and supply side - check that they have been wired up the right way... It is possible that they may have been reversed - so on is off and off is on etc.

With a 45a DP switch, the 'on is off, off is on' scenario is impossible.
It would need to be a 'two-way' or 'double-throw' for that to happen, which it is not.
The only difference would be that the neon (on the switch) would stay on (if it's got one) all the time.

 

[riveralt]

With a 45a DP switch, the 'on is off, off is on' scenario is impossible. It would need to be a 'two-way' or 'double-throw' for that to happen, which it is not..

I was thinking more along the lines of line in neutral and vice versa.

The only difference would be that the neon (on the switch) would stay on (if it's got one) all the time.

Yes I am aware of that one.

 

[wingcoax]

If the switch is DP it makes no difference electrically which way round the conductors are as both legs are broken.

 

[riveralt]

If the switch is DP it makes no difference electrically which way round the conductors are as both legs are broken.

I know I'm scratching at straws just trying to think of ways in which the circuit is still live when both the 45amp dual pole switches are off - either they are both broke or.....???