Really low Ze from earth rod!

[SPARTYKUS]

Showing off now Trev!

 

[Richard]

Are you sure there is definatly no contact between the suppliers earthing arrangement and where ever you tested from? Is the small DB metal clad? Did you physically d/c your earthing conductor from the earth terminal to ensure no other paths? Sorry not trying to teach you to suck eggs - just checking!

 

[LukeBuckaz]

Well the armoured is glanded into a metal clad box at the 'new' end then from the metal clad box to a card meter (the stable has been converted into a dog grooming room and the owner wants the lady who is running the dog grooming to pay her own way) now the armoured is a 3core I did use one of the cores as an earth but terminated this at the metal clad box.

 

[trev]

I've always put at least two rods on a TT mate as it was how I was taught but this time I'd gotten the first one in and got about 180/90 coupled another knocked that in and took 100 ohms off that then I thought oooo how low can you go so whacked the third in, read 0.29 and thought I'll stick there. Gaffer wasn't happy at first when he spotted all his shiny new rods had gone but when he saw my test sheet I had yet another convert

 

[richy3333]

have you stabbed it through the neutral of the supply cable?

pmsl

 

[LukeBuckaz]

Now I did not disconnect the main earth when conducting the Ze (I have slapped my own wrist, and slightly embarrassed) there is only two circuits on the new DB a lighting circuit with 2 lights fitted. Both plastic light fittings fixed to wood. Also 4 double socket outlets fixed to a block built wall, so I cannot see that there are any parallel paths back to the suppliers earthing arrangement.

 

[somersetsparks]

I've always put at least two rods on a TT mate as it was how I was taught but this time I'd gotten the first one in and got about 180/90 coupled another knocked that in and took 100 ohms off that then I thought oooo how low can you go so whacked the third in, read 0.29 and thought I'll stick there. Gaffer wasn't happy at first when he spotted all his shiny new rods had gone but when he saw my test sheet I had yet another convert

Just the difference between 3/8" rod and 5/8" rod is a lot though isn't it, I can't believe how many people just stick in 3/8" rod, I have only used these for temporary stakes for genny's and cabins.

 

[jdd]

Mate, I would definitely dissconnect the main earth and re test.

 

[trev]

Is the CU metal clad and was the swa earthed to that earthing bar?
If so there's your reason for the low reading Luke.
DC the main earth when you get back to it and get a reading just off your rod then let us know

 

[StuSpiers]

Just the difference between 3/8" rod and 5/8" rod is a lot though isn't it, I can't believe how many people just stick in 3/8" rod, I have only used these for temporary stakes for genny's and cabins.

You can't really blame people when it is standard fair at all wholesalers.

In fact most younger sparks wouldn't even be aware there is a problem with it.

 

[trev]

Just the difference between 3/8" rod and 5/8" rod is a lot though isn't it, I can't believe how many people just stick in 3/8" rod, I have only used these for temporary stakes for genny's and cabins.

Hell yeah mate I won't use those little bloody twigs, I've seen them used a million times and then heard"Oh that'll be fine".
Not in my book

 

[LukeBuckaz]

the CU is metal clad but the earth from the armouring or that 3rd core was not connected. I will go back, disconnect the earth rod conductor from the earth bar and re-test. Would it hurt to connect that 3rd core of the armoured into the earth bar?

 

[trev]

Is the armouring earthed?

 

[jdd]

You need to disconnect all parallel paths dude, the only way to effectively do that is to disconnect from MET and test to that only, I think you may have been reading through the SWA.

Did you get my personal message?

 

[LukeBuckaz]

yes the armouring is earthed but it is glanded to a seperate metal clad box, not the metal clad fuse board. Sorry I didnt make this clear.

 

[LukeBuckaz]

When I go back I shall definitely disconnect from the earth bar and retest. If the reading was through a parallel path, and the reading through JUST the earthrod was unacceptable, I shall obviously install more earth rods until an acceptable reading is obtained!

 

[Richard]

yes the armouring is earthed but it is glanded to a seperate metal clad box, not the metal clad fuse board. Sorry I didnt make this clear.

Is there any chance that you've screwed these metal enclosers through plasterboard (or what ever) and into cellotex or other foil insulation which could give you a path between the two?

 

[LukeBuckaz]

No mate everything fixed directly to a block wall using brown plugs and 1 1/2" x 10 screws

 

[SPARTYKUS]

Luke it would be really interesting to know the result.

 

[soulman]

I very much doubt there are no parallel paths. But i am taking on board trev's & others post's as i usually use the twigs, I will start using the 5/8 and try and get a couple in. I hate putting rods in just in case you hit any service pipes.

Cheers