TT System Query

[sbrown2]

Good Morning

I would like some advice.

Working on a Domestic TT System. Primarily a kitchen refurb. The customer in my case is the contractor. I told him there should be an earth electrode around. I tried to locate and could only locate 6mm earth cable to a disused lead water pipe. Eventually found the earth electrode with the cable disconnected. The original consumer unit has no RCD protection and is around/at least 25 years old. I've been told to ignore this consumer unit and fit new for the kitchen with 30mA protection.
Questions

1. If resistance readings are ok can the lead pipe suffice as the earth electrode?
2. Would you put the disconnected electrode back into service if the tests are good?
3. Is it normal practice to leave customer CU and fit new one to specification?

Any help would be appreciated.

 

[richy3333]

That is why a ground level Earth pit should ''Always'' be provided over an earth rod connection!! How many actually get one these days, is somewhat questionable...

Why aren't sparks putting in earth pits and labelling? Laziness? I regularly read similar posts on the forum about TT systems and a disconnected earth cable. Can't believe it.

The OPs customer is amazing too, happy to purchase a new swanky kitchen but not as concerned about electrical safety?

 

[richy3333]

What type of building is the installation in? Is it something temporary? Site power?

There are various special locations TN-C-S is not allowable under 7671

The Electrical safety, Quality and Continuity Regulations is what the BGB refers to

 

[aaelectric]

its a commercial shop with flats above.Isit because its teemporary you have to put an earth rod??
what test do you have to do with no power connected??

 

[telectrix]

all you can do is your dead tests. R1+R2, . r1,rn,r2 (ring finals). IR tests.

 

[aaelectric]

Hi telectrix
I have done the test on the circuits on fuse board but what test can you do for earth rod??
Is there a certain size you need and how deep??
Also i have no access to put outside, isit ok to put next to fuse board burried?

 

[telectrix]

if you are close to the building wall you will have to go deep to penetrate the crap buried by the builders. 5/8" rods, at least 2 screw together sections. and have to hope for a decent reading when you can measure Ze. there is a way to measure the earth rod's impedance without power, but as i have never done that, i can't advise.

 

[aaelectric]

when you say 2 screwd together is that side by side or in length? i will put as far down as possible, will dno test when they connect or will i have to???

 

[richy3333]

Usually screwed together.
I assume as the DNO are not supplying an earth you will be required to test it yourself

 

[acvc]

Is that an official 'method' of finding out whether PME is applicable then? Do a 'Ze' L-N?

 

[telectrix]

no, it's not. the only way as i know is to measure the pssc and pefc, and if they are as near as damn it identical values, then you've got pme.

 

[aaelectric]

Hi
as there is no power to fuse board as they havn connected it up yet. i cannot take out main fuse. i cannot do a ze reading, so what can i doo??
. does the rod have to go all the way into the ground?
They have installed a new 3phase pme supply why can they not coonect onto their earth?
Its a temporary supply and temporary db!!