Broken PEN and HSE response!

[ericmark]

This report says how the HSE response seems inadequate, once I was indecisive now I am not so sure, is there really a problem?

The IET wiring matters of march 2021 seems to have gone off line, maybe they are reconsidering? However the question is what is the risk, OK EV charging point or hot tub and we have to be very careful, but what about an outside boiler, if housed in a plastic shed thing, then only during maintenance is it really a problem.

Nearly all garden equipment is class II, so in real terms the biggest problem is bonding on the wrong side of an isolation piece with a gas supply.

So looking at risk assessment, which is the worst?
A large cross sectional area earth wire which can carry enough current to melt the gas pipe?
or
A small cross sectional area earth wire which will itself melt before the gas pipe?

What I am saying is my single rod in the ground is not a problem as if there is a loss of PEN, it will only carry around 10 amp, but as I have related many times, the radio ham with an earth mat in his garden, the earth was too good, and the cables melted.

I look at where I work, metal frame shed, bonded to 8 mile of railway line, loss of PEN is unlikely to cause a danger, in fact the problem is more even working out there has been a loss of PEN.

So we read read these reports but is it really a problem?

 

[SUNRAY]

This report says how the HSE response seems inadequate, once I was indecisive now I am not so sure, is there really a problem?

The IET wiring matters of march 2021 seems to have gone off line, maybe they are reconsidering? However the question is what is the risk, OK EV charging point or hot tub and we have to be very careful, but what about an outside boiler, if housed in a plastic shed thing, then only during maintenance is it really a problem.

Nearly all garden equipment is class II, so in real terms the biggest problem is bonding on the wrong side of an isolation piece with a gas supply.

So looking at risk assessment, which is the worst?
A large cross sectional area earth wire which can carry enough current to melt the gas pipe?
or
A small cross sectional area earth wire which will itself melt before the gas pipe?

What I am saying is my single rod in the ground is not a problem as if there is a loss of PEN, it will only carry around 10 amp, but as I have related many times, the radio ham with an earth mat in his garden, the earth was too good, and the cables melted.

I look at where I work, metal frame shed, bonded to 8 mile of railway line, loss of PEN is unlikely to cause a danger, in fact the problem is more even working out there has been a loss of PEN.

So we read read these reports but is it really a problem?

Which brings me back to the hazard of working in a property where the (ex telephone exchange) TT earth was the only earth on a substation and that was only via a 1 (or 1.5)mm² T&E earth on an outbuilding submain for a Koi pond and swimming pool.

 

[ericmark]

I would love to know where the earth went with my parents house. Only earth I could find was the old GPO earth for the party line. We commissioned a wet room to be built, and the builder ran off, so my son and I had to complete it.

A new consumer unit had been fitted by the builders electrician, so it was unclear where the original earth had been. Well more like invisible, I could not find any sign of where it had been, got a TN-C-S installed.

I will guess it was the water pipe, they did not have gas when they moved in, that came latter when the coke ovens closed and the supply of number 4 coke at very low cost dried up. So dad had central heating fitted.

But at some time the water main was replaced with plastic.

I also had a friend still with an ELCB-v fitted, which made the earth rod useless.

I am sure my friend would not have wired his shack, and also sure my dad did not disconnect the earth, so the question arises who did? The TT supply with the ELCB-v came from a stone house, very small, to a wood framed house and the latter had RCD protection, the test button did not work, and the RCD tester would not trip it, due of course as the ELCB-v resistance was too high.

So who fitted the RCD clearly without testing it? It could have never worked. I fitted a new consumer unit in the stone cottage, with an RCD and the ELCB was by-passed. I could just about reach it, under a stone slab, but no way could I remove it, so it stayed as a simple isolator, the ELCB function was disabled. I suppose some one will find it one day and wonder what it is?

But the question remains, is TN-C-S a problem? My house when I have a grid connection is TN-C-S, but also has an earth rod as I have an UPS, I did think TT but not so sure, if I have no grid supply, then also nothing to bond neutral to earth, so suppose it's an IT supply.

 

[flameport]

But the question remains, is TN-C-S a problem?

Installed and maintained properly it can be safe.
Installed properly means earth electrodes connected to the PEN conductor at every supply point, which is every property.

Installed as it has been in the UK with no local electrodes and underground cables/joints in many areas now 50+ years old, it is not.

Even when done correctly there are still problems.
Broken PEN can be concealed by the presence of earth electrodes at each property, and the high currents which flow in the bonding connections cause significant magnetic fields.

 

[bernardgreen]

But the question remains, is TN-C-S a problem?

It is potentially a problem when there is a network fault.

This a very clear explanation of the dangers that a broken PEN will create in other houses

 

[EFLImpudence]

Perhaps the DNOs should have been forced to maintain the TN-S supply.

 

[bernardgreen]

My Lords, I rise to address the...

Part of Levelling-up and Regeneration Bill - <i>Report (8th Day)</i> – in the House of Lords at 5:30 pm 18 September 2023

www.theyworkforyou.com

In April, I read in Engineering & Technology about concerns relating to the risks of neutral current diversion, known as NCD. The author was investigative journalist, Conor McGlone, who wrote of experts expressing concerns of the real risk of deadly gas explosions and fires in the UK due to a common fault on the electrical system. They claim that the fault is neither acknowledged by distribution network operators or the Health and Safety Executive. In short, and keeping off the detailed techy stuff, a neutral current diversion can occur when the combined protective earthing and neutral conductor fails. The current is then diverted by making a circuit via exposed metal workings on buildings including gas, water and oil pipes. In other words, electricity can flow through gas meters in these circumstances.

 

[ebee]

I must admit I have an aversion to TNC-S , however, when we did commonly have pretty much real TNS then how would we know that nobody nearby had not put a near dead short from their own N to E thereby making ours very TNC-S like and we would be non the wiser

 

[SUNRAY]

I must admit I have an aversion to TNC-S , however, when we did commonly have pretty much real TNS then how would we know that nobody nearby had not put a near dead short from their own N to E thereby making ours very TNC-S like and we would be non the wiser

I knew someone who automatically linked E & N whenever he did any electrical work or constructed any kit, it caused all sorts of problems when RCD's started appearing.

 

[EFLImpudence]

when we did commonly have pretty much real TNS then how would we know that nobody nearby had not put a near dead short from their own N to E thereby making ours very TNC-S like and we would be non the wiser

Why would it matter with a still satisfactory intact earth?

 

[ericmark]

Installed and maintained properly it can be safe.
Installed properly means earth electrodes connected to the PEN conductor at every supply point, which is every property.

Installed as it has been in the UK with no local electrodes and underground cables/joints in many areas now 50+ years old, it is not.

Even when done correctly there are still problems.
Broken PEN can be concealed by the presence of earth electrodes at each property, and the high currents which flow in the bonding connections cause significant magnetic fields.

PME is TN-C-S but TN-C-S is not always PME. The M of PME stands for multiple and with multiple earth rods as you rightly say a broken PEN can be masked with multi earth rods, but it does in the main hold the voltage to within 50 volts of true earth, but this is not the case with TN-C-S.