The £1300 AFDD consumer unit

mapj1:

Indeed and modern earthed concentric and waveform cables are very like a low impedance coax, at least at these frequencies, and voltages between  L-N or L-L tend to get smoothed out by that - indeed long range powerline comms, which I do not like for other reasons, relies on this transmission line bahaviour.


If you look at the design of nuclear bunkers, or EMP proof test chambers. you will see we very carefully try to bring all the services in through one "access panel", or at least one all-metallic wall, so that there is in effect an low impedance bond between comms lines and mains lines,, plumbing and similar. In the 'dipole' view of the world, while we cannot stop voltages being induced external to the facility but we can give the current an easy path that does not involve passing any significant fraction of it though sensitive equipment.

While this is not possible in most buildings, but it is worth bearing in mind as the only reliable way to protect equipment - so  for example TV antenna feeders that are connected to the mains ground are less likely to blow up the TV they are attached to and soon .

Mike

 

Definitely, this is an approach that can help ... although it sometimes just "moves the problem on elsewhere". I've used it myself.

mapj1:

Indeed and modern earthed concentric and waveform cables are very like a low impedance coax, at least at these frequencies, and voltages between  L-N or L-L tend to get smoothed out by that - indeed long range powerline comms, which I do not like for other reasons, relies on this transmission line bahaviour.


If you look at the design of nuclear bunkers, or EMP proof test chambers. you will see we very carefully try to bring all the services in through one "access panel", or at least one all-metallic wall, so that there is in effect an low impedance bond between comms lines and mains lines,, plumbing and similar. In the 'dipole' view of the world, while we cannot stop voltages being induced external to the facility but we can give the current an easy path that does not involve passing any significant fraction of it though sensitive equipment.

While this is not possible in most buildings, but it is worth bearing in mind as the only reliable way to protect equipment - so  for example TV antenna feeders that are connected to the mains ground are less likely to blow up the TV they are attached to and soon .

Mike

 

Definitely, this is an approach that can help ... although it sometimes just "moves the problem on elsewhere". I've used it myself.