I have just been involved in a situation where temporary loss of neutral on a TNCS system caused thousands of pounds worth of damage. It seems this loss of neutral situation, either within or outside the installation, is occurring more frequently. SPDs are now commonly fitted but at DBS and generally with a Up in the order of 860v, so giving no protection on loss of neutral in a three-phase and neutral system. Cost benefit analysis across the national spectrum might not support a compulsion but is it time designers should be raising the issue with clients and at least offering a solution. On the other hand, is there a packaged solution?
You could just alter the pipe work in your installation, and ensure that it is all plastic, so that main equipotential bonding is not required. The gas main up to the house would be plastic in most cases, and just internal gas pipes would be metal.
This is a huge assumption. There are many 1000's of properties out there with one, or both, water and gas services in metal. My own house still has both in metal - gas is the big issue because the internal piping still has to be metal. Whilst a lot of the internal water pipework has been replaced with plastic, a lot of the central heating is still metal, and still very serviceable.
Whilst the mains in the street have possibly been replaced, what we don't know is how far the joints are to earthing for the PME ...
Other premises will have different issues - for example, premises that require LPS there's just no way of getting away from conductive stuff connected to the ground.
I'm definitely an advocate of the approach of using the smart meter system, and it's a great idea - it's just that I think it would be better if the DNO were to be alerted to the issue, especially single-phase installations, to avoid nuisance-trips.
You could just alter the pipe work in your installation, and ensure that it is all plastic, so that main equipotential bonding is not required. The gas main up to the house would be plastic in most cases, and just internal gas pipes would be metal.
This is a huge assumption. There are many 1000's of properties out there with one, or both, water and gas services in metal. My own house still has both in metal - gas is the big issue because the internal piping still has to be metal. Whilst a lot of the internal water pipework has been replaced with plastic, a lot of the central heating is still metal, and still very serviceable.
Whilst the mains in the street have possibly been replaced, what we don't know is how far the joints are to earthing for the PME ...
Other premises will have different issues - for example, premises that require LPS there's just no way of getting away from conductive stuff connected to the ground.
I'm definitely an advocate of the approach of using the smart meter system, and it's a great idea - it's just that I think it would be better if the DNO were to be alerted to the issue, especially single-phase installations, to avoid nuisance-trips.
