High TT Ze!Personally

[Ross1]

Hi guys, I would like to know what code you would give for a reading of 435 ohms on an EICR. Personally I'd give a C2.

Regards

 

[Guest123]

In your opinion then, why is it potentially dangerous???

I'm assuming there are RCD's present???


Not having a pop or anything, just trying to stimulate thought & debate.:sultan:

 

[telectrix]

agree.

 

[Ross1]

Well guys, I'm not gonna pretend I'm an expert on EICR's. I will continue learning as will all of us. My reasoning is that earthing is extremely important in an installation, so as it is more than double the recommended value as set out in the BGB.

Regards

 

[rich.250]

That figure is a bit misleading though, obviously the lower the better is the best approach.

But you could say if it looks in sound condition and you don't think its going to alter due to weather conditions etc C3?? hard to really judge
Also obviously depends on if its on RCD an the mA rating.

There are a lot of factors that would contribute in my eyes,
although i don't think you're going far wrong there

Never going to hurt to improve an earth path is it

 

[Guitarist]

I'm sure that a bucket of water will bring that reading down to under 200

*Tin hat on*

 

[Ross1]

I'm sure that a bucket of water will bring that reading down to under 200

*Tin hat on*

I do a lot of work on TT installs, I always have to knock 2 x 5/8 rods in to get the reading below 200ohms. I have still not achieved a reading lower than 100 even with a bucket of water

 

[rich.250]

Ive gone down 4m at my
House and still up 350 ohms.
Even tried in numerous places.
So I got tncs lol

 

[trev]

Ross you might be pleasantly surprised by what a third or fourth rod will do for you.
Last time I did a TT I drove 4 couplable rods and got 0.29. I didn't get that low when I rewired my own home

 

[Deleted member 9648]

Think it's hard to justify a code 2 (potentially dangerous) if the install is protected by at least one functional 30 ma RCD which we know will provide protection in accordance with BS 7671 up to 1667 ohms.....After all bringing it down to <200 ohms as recommended in Bs 7671 will make no difference to the safety of the protection as it stands. Code 3 for me.
This is not intended to start another Ra 'debate' with E54....but an EICR is based on Bs7671 whether E54 or anyone else agrees or not,and coding should be based on that alone,not personal views on Ra values.

 

[Ross1]

Ross you might be pleasantly surprised by what a third or fourth rod will do for you.
Last time I did a TT I drove 4 couplable rods and got 0.29. I didn't get that low when I rewired my own home

What u using to knock rods in that deep Mate.

 

[Marvo]

Ross you might be pleasantly surprised by what a third or fourth rod will do for you.
Last time I did a TT I drove 4 couplable rods and got 0.29. I didn't get that low when I rewired my own home

I agree, often you keep adding rods with only a steady improvement in impedance readings then all of a sudden you go one rod deeper and there's a massive improvement in readings. I assume it's where you get below the water table or maybe a seam of better ground material.

 

[trev]

What u using to knock rods in that deep Mate.

An apprentice, what else would you use

 

[trev]

Seriously though, I have a home made attachment for me SDS, I drove 2 checked the reading and got 185ish. Drove another and got sub 100 then I thought how low can you go, drove another got me 0.29 and then thought happy days I'll stick with that.

 

[MarkieSparkie]

Seriously though, I have a home made attachment for me SDS, I drove 2 checked the reading and got 185ish. Drove another and got sub 100 then I thought how low can you go, drove another got me 0.29 and then thought happy days I'll stick with that.

Last time we had that low Ra on a TT was many years ago. An eager young apprentice had driven in the rods and was feeling real chuffed achieving an excellent earth installation. A week later the firm got a call from Wessex Water saying they had done a sewer survey in the area due to an apparent blockage and they had found our earth rod had broken through in to sewer and the end of it was sat in a foot of sewer water with detritus and debris piled up around damming the pipe ... I was that red faced and embarrassed apprentice, particularly when the gaffer told me he was docking my wages to pay for sewer clearance.