TN-C-S and earth electrode?

[Staffie]

Why would someone want to go and put one in on a PME system?

On a closer examination, I noticed that the main earthing conductor had been removed from the PME cut-out!

So, had the spark who installed this electrode just gone straight in, done a Zs which appeared excessively high without checking the intake? Or was he out to make some money during these hard times? Or was there a more logical reason for his actions?

Up front is an old Crab with a 63A 30mA RCD, which I'm sure doesn't work properly? Will confirm this when I've tested it!

It's left me pretty baffled to be honest...

 

[electro]

Hi


There are many reason why TT systems are installed. The biggest one he may have been refused by the DNO. Many DNO have different rules around the country regarding TN-C-S connections.


Factors - Type of build and use, plays a big part other factors steel framed houses, agricultural, swimming pools, different levels of build and detached building from property.


regards

 

[Spudnik]

What you need to do is disconnect the rod and test Ze and see if it complies.

If not, then it may be that the rod is supplementary.

OR, when (if) the supply was converted to PME the rod never got removed.

 

[Staffie]

OR, when (if) the supply was converted to PME the rod never got removed.

The rod was put in about 3 weeks ago!

It's an ex council house on a small estate, not like it's out in the sticks etc?!

I'm going to disconnect it, stick some 16mm into the cut out and do a Ze, I 'll post the results!

Cheers!

 

[ooh that hertz]

Staffie

Was it an electrician who installed the rod or has the cut-out been upgraded.

On a few occasions i have seen the utility company install rods as part of the PME system at various points in the network, odd location to put one though i think.


Just spotted you said the PME link to the neutral was missning.......I went to a job other day to recheck the Ze on a cut-out after the old one had been replaced, L-N....looks good, L-E.....hmmmmm no reading. Just happened to pull, very lightly, on the 10mm earth that had been stuffed up inside the cut-out and the bloody thing came out .....barely connected. PME link also not installed

Called UU out, obviously someone was up for a **********, vans arrived, vans went, photos taken. When the guy asked what the inital loop reading he sounded a bit shocked

Dont trust the Utilities

Got any further with it?



MOD EDIT: WATCH THE LANGUAGE

 

[chocolate]

IF in doubt, don't reply on TNCS unless you can be sure that should the neutral fail, you won't be livening up every exposed conductive part in the building.

Too many people think TNCS is the solution to easy earthing. It can be a potential disaster.

It is the electrican that should ensure that a suitable earth path exists - not the supply authority.

 

[vardymr2]

Another reason could be the main gas and water bonding is not in 10mm and if its a nightmare to upgrade the bonding to 10mm i have heard of people in the council changing the system to a TT so it complies with regs. CRAZY i know but it happens trust me

 

[Staffie]

I'm supposed to be going back out to the job in a few weeks to rewire the kitchen lights as this is a real disaster! Some 'clever dick' wired it up so the light fittings are permanently live (N to E), the kitchen light switch has to be 'on' in order to make the conservatory light switch live which in-turn makes the outside light switch live!!!

The cable which supplies some bulkheads in the garden in ran in some old hosepipe, I could go on. I'll get some photo's when I'm over there in a few weeks!

BTW, it was the sparky who installed the earth rod not the supply authority!

 

[Spudnik]

I'm supposed to be going back out to the job in a few weeks to rewire the kitchen lights as this is a real disaster! Some 'clever dick' wired it up so the light fittings are permanently live (N to E), the kitchen light switch has to be 'on' in order to make the conservatory light switch live which in-turn makes the outside light switch live!!!

The cable which supplies some bulkheads in the garden in ran in some old hosepipe, I could go on. I'll get some photo's when I'm over there in a few weeks!

BTW, it was the sparky who installed the earth rod not the supply authority!

Its not unusual to have other switches connected to the switched live of another switch.

It does give the facility to turn off all the lights in one go.

 

[Staffie]

Its not unusual to have other switches connected to the switched live of another switch.

It does give the facility to turn off all the lights in one go.

Point taken, but would you have wired up this type of set up in someone's home???

 

[chocolate]

Sounds like a 'didn't really know what I was doing, but when i switched it all on, it seemed to work' kinda job. As an experienced sparks, sort the Earthing out to the standard you want and expect it to be. And rewire those kitchen lights !!!!

 

[rob1967]

I'm supposed to be going back out to the job in a few weeks to rewire the kitchen lights as this is a real disaster! Some 'clever dick' wired it up so the light fittings are permanently live (N to E), the kitchen light switch has to be 'on' in order to make the conservatory light switch live which in-turn makes the outside light switch live!!!

The cable which supplies some bulkheads in the garden in ran in some old hosepipe, I could go on. I'll get some photo's when I'm over there in a few weeks!

BTW, it was the sparky who installed the earth rod not the supply authority!

Will be intresting to look at thoses pictures when you get them.................it's strange what some sparks do