PME & Broken neutral

[Deleted member 9648]

I can only recall one instance of a broken neutral causing a shock hazard in my time,over 30 yrs,that in a butchers shop in a village.
Regarding the 200 ohms value of an earth rod....it is ridiculous to mockingly quote this figure in conjunction with a TNCS where such a rod may be used to limit the danger of a lost N....the 200 ohms is intended for a TT system designed to operate at high Zs values....not a system designed to utilize a low value of Zs.

 

[Engineer54]

Well aparently they have to apply for PME with who ever they pay their bills too.
The option was to dig up the street! but in his words its probelly best to PME the head, but as the meter was supplyed by someone else, it needs to be applyed for by the occupier. he even volentered to return and reseal, so he wasnt dodging the job, took me like 2 minuits. And as ive mentioned I worked for Eastern Electricity so it wasnt a big deal.
Looking back I could have kicked up a fuss, Have you ever tryed talking to the DNO!!! I bet NOT,, theres only so much Barry Manalow you can take....

You don't just PME when there is a problem with a TN-S supply, not even the DNO's would be foolish enough to do that!! The distribution supply cable in question needs to meet certain criteria before N-E connections can be made to that supply cable.

Not saying that the DNO's these day's are anything like the old Electricity Boards, but they DO take problems with PME supplies very seriously, and generally WILL be on site within the hour when a problem has been brought to their notice. More than they dare do, is allow a fault on PME'd system persist for any length of time....

Wirepuller

My mentioning the 200 ohm Ra was made tongue in cheek, but by the same token, how many of these newer or Electrical Trainee's electricians would know any different?? Unless of course they are members here and had the good sense to ask, before banging in one of those twigs...

 

[bigspark17]

An rcd wouldn't detect this and would stay in the functional position.. Some believe the bet way to protect against this rare but terrifying fault would be a contactor after the main switch.. Thus cutting the supply to this point at least.