High TT Ze!Personally

[Guitarist]

Nothing quite like being an apprentice....

 

[telectrix]

sometimes electrics is a crap job, innit?

 

[Richard Burns]

sometimes electrics is a crap job, innit?

Only Sometimes? Lucky you!

 

[Engineer54]

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.

And i agree with you, ....to a point!! ..lol!!

There are most certainly times, due to very unfavorable ground conditions where your not going to even achieve the numbty BS 7671 200 ohms Ra. But i think you'll agree that in such circumstances it's sensible to add an up-front S type RCD, rather than totally relying on a single RCD device!!?

Mind, there are some members that blindly believe that all or single RCD devices can always be relied on, because they virtually never fail!! Well, that's what they have read anyway!!

 

[Deleted member 9648]

And i agree with you, ....to a point!! ..lol!!

There are most certainly times, due to very unfavorable ground conditions where your not going to even achieve the numbty BS 7671 200 ohms Ra. But i think you'll agree that in such circumstances it's sensible to add an up-front S type RCD, rather than totally relying on a single RCD device!!?

Mind, there are some members that blindly believe that all or single RCD devices can always be relied on, because they virtually never fail!! Well, that's what they have read anyway!!

Agree with upfront S type....but the point I was making was for the purposes of an EICR ( which is the OP's query) the only consideration is compliance with Bs 7671....it is not the done thing to introduce personal preferences into coding of defects.

 

[Engineer54]

I will agree with that side of things. Defect coding should conform/comply with BS7671.

 

[richy3333]

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

411.5.3 Note 2 merely states that anything over 200 ohms MAY not be stable. So, is your 435 ohms a stable reading? Has there been previous tests of the Ra for you to compare it with? What other protection does the installation have?

I don't think you can just say because the Ra is 435 ohms it is unstable/too high?

I've got some good Ra readings recently on new installs - give a burley customer 4 rods, connectors, a sledge hammer and the knowledge that if I don't have to install the rods he saves money; then all he only sees is a challenge - less than 40 ohms

 

[Guitarist]

411.5.3 Note 2 merely states that anything over 200 ohms MAY not be stable. So, is your 435 ohms a stable reading? Has there been previous tests of the Ra for you to compare it with? What other protection does the installation have?

I don't think you can just say because the Ra is 435 ohms it is unstable/too high?

I've got some good Ra readings recently on new installs - give a burley customer 4 rods, connectors, a sledge hammer and the knowledge that if I don't have to install the rods he saves money; then all he only sees is a challenge - less than 40 ohms

So let the customer sink the electrodes with the understanding that if he/she breaks any drains then it's their fault.... I like your style

 

[Geordie Spark]

An apprentice, what else would you use

I could lend ye Wor Lass if you haven't got an apprentice and she's not at the airport kick starting jumbo jets

 

[Deleted member 9648]

411.5.3 Note 2 merely states that anything over 200 ohms MAY not be stable. So, is your 435 ohms a stable reading? Has there been previous tests of the Ra for you to compare it with? What other protection does the installation have?

I don't think you can just say because the Ra is 435 ohms it is unstable/too high?

I've got some good Ra readings recently on new installs - give a burley customer 4 rods, connectors, a sledge hammer and the knowledge that if I don't have to install the rods he saves money; then all he only sees is a challenge - less than 40 ohms

435 ohms? in the event of an earth fault your overcurrent device wont operate,your RCD will.
40 ohms? in the event of an earth fault your overcurrent device wont operate,your RCD will.

Yep,can see the real advantage of getting 40 ohms.:rolleyes2:

 

[Engineer54]

435 ohms? in the event of an earth fault your overcurrent device wont operate,your RCD will.
40 ohms? in the event of an earth fault your overcurrent device wont operate,your RCD will.

Yep,can see the real advantage of getting 40 ohms.:rolleyes2:

Here we go again!! lol!! Anyone with an once of commonsense would be far happier with a stable deep driven 40 ohm Ra, than your all singing, all dancing but useless single twig 200 ohm Ra, that will never become stable!!
As this example is made up of 4 coupled rods, the chances are that the final Ra will be substantially lower, after the soil has consolidated/compacted around the top 3 rods...

Seems your reverting back to relying on a single RCD device for a TT system again here too!! lol!!

 

[richy3333]

Cheers E54.
I nearly went back today and ripped the whole lot out so I could stick a banana in the ground, hoping the potassium would give me a better reading

 

[Engineer54]

Cheers E54.
I nearly went back today and ripped the whole lot out so I could stick a banana in the ground, hoping the potassium would give me a better reading

No problem ...lol!! The whole idea here, should be to encourage electricians to do there best within reason, to get the best Ra value they can by applying a little thought in what they are doing!! Not encouraging people to just bung a twig in the ground and hope for the best, mainly because it's never gonna happen.

 

[Deleted member 9648]

No problem ...lol!! The whole idea here, should be to encourage electricians to do there best within reason, to get the best Ra value they can by applying a little thought in what they are doing!! Not encouraging people to just bung a twig in the ground and hope for the best, mainly because it's never gonna happen.

If you get a TN value which will operate an overcurrent device then I salute you,the end result was worth the effort....if you think 40 ohms is any better than 100 ohms or 200 ohms you are kidding yourself.....

 

[richy3333]

Yeah, those Screw fix (et al) twigs are a joke.
To be honest I was happy with 40ish ohms because when put into context, when I've PIR'd plenty of Nationally owned campsites I've measured far, far worse readings