Eicr earth rod over 200ohm

[D Skelton]

A 30mA RCD is going to trip all the same at 199ohms and 250ohms, the only difference between the two is that one is over the 'suggested' value in the regs regarding stability. The fact is, you can get stability from high values, this is just as likely as a high value being unstable (round my way anyway), that is why I would want to check this out before deciding whether or not I would recommend improvement.

I can see the point regarding a C3, and I wouldn't see this as wrong, if the aim was to recommend improvement with a C3 and then check out it's stability I can go with that. Either way though, an s-type up front would be a firm recommendation of mine.

 

[MDJ]

I beg to differ, reg 411.5.3 states that Ra must be equal or under 50V/Idelta n which in the case of a 30mA device is 1667ohms

No it is 200 or under not 1667, I understand your thought process, but your not correct, to suggest an ra rating of 1667 is fine by regs is wrong, it is considered unstable over 200 ohms.

 

[MDJ]

I beg to differ, reg 411.5.3 states that Ra must be equal or under 50V/Idelta n which in the case of a 30mA device is 1667ohms

thethread keeps crashing so I have no idea if you ever get to read this, however the regs state the maximum Ra rating on a tt system is 200 ohms. I totally understand your thinking, but 200 ohms is the limit, I will quota a reg number later when Dan has stopped erasing all my Flucking posts

 

[davesparks]

As far as I know, and have found so far there is no stated max value for RA other than a statement that it shoudl be as low as possible.

Regulation 411.5.3 is met if the Zs of a circuit where a 30mA RCD is used as the method of fault protection is less than 1667ohms. (from table 41.5)

People need to stop quoting/using just the little part of the regulation which serves their purpose and use the whole of the regulation as it was written.

I don't suppose many here have considered regulation 411.5.4 at any time when installing TT systems

And I'm sorry MDJ but as far as I can tell 200 is not stated as the maximum limit of Ra, the only line i've found about it so far is that Ra must be as low as practicable and a value above 200 may not be stable.

 

[MDJ]

I beg to differ, reg 411.5.3 states that Ra must be equal or under 50V/Idelta n which in the case of a 30mA device is 1667ohms

I have replied to this post 3 times now, shall I bother to try a 4th? okay I will try again, if Dan does not edit this post I will try to post up some regs later proving my point, the site is all over the place at the moment and no posts are safe from erasion.

 

[MDJ]

As far as I know, and have found so far there is no stated max value for RA other than a statement that it shoudl be as low as possible.

Regulation 411.5.3 is met if the Zs of a circuit where a 30mA RCD is used as the method of fault protection is less than 1667ohms. (from table 41.5)

People need to stop quoting/using just the little part of the regulation which serves their purpose and use the whole of the regulation as it was written.

I don't suppose many here have considered regulation 411.5.4 at any time when installing TT systems

And I'm sorry MDJ but as far as I can tell 200 is not stated as the maximum limit of Ra, the only line i've found about it so far is that Ra must be as low as practicable and a value above 200 may not be stable.

OMG I can see your post at last lol, give me a few mins to get a reg up Dave

 

[davesparks]

OMG I can see your post at last lol,

Lol, I can see it now too! at least I had time for a cup of tea between posting it and it actually appearing!

Time now is 20:55, post the time when you first get to see this and we'll see how long it actually takes!

 

[Guest55]

......... give me a few mins to get a reg up Dave

1 hour later.......

MDJ has left the building lol.

 

[davesparks]

1 hour later.......

MDJ has left the building lol.

It says one hour ago, but that post only appeared about 20 minutes ago.

 

[Guest55]

he's still waiting for a taxi then......

 

[GLENNSPARK]

No code, I'd note it and recommend the customer allow at least a quaterly Ra reading to be taken to further determine it's stability. Another recommendation would be to fit an s-type up front.

Tin hat firmly strapped on!!!

hmm...

unreliable Damian.

lets face it the value is going to fluctuate wildy....the whole idea of depth is stability....

 

[davesparks]

Playing devils advocate for a minute, what's to say it isn't deep already?

 

[GLENNSPARK]

As far as I know, and have found so far there is no stated max value for RA other than a statement that it shoudl be as low as possible.

Regulation 411.5.3 is met if the Zs of a circuit where a 30mA RCD is used as the method of fault protection is less than 1667ohms. (from table 41.5)

People need to stop quoting/using just the little part of the regulation which serves their purpose and use the whole of the regulation as it was written.

I don't suppose many here have considered regulation 411.5.4 at any time when installing TT systems

And I'm sorry MDJ but as far as I can tell 200 is not stated as the maximum limit of Ra, the only line i've found about it so far is that Ra must be as low as practicable and a value above 200 may not be stable.

the reason that 200 ohms is given as a benchmark figure it that its felt that this could rise by upto 8 times in worst case conditions (dry, dusty, hot conditions)

so 8X 200= 1600

still below the 1667 max for 30mA RCD fault protection.

this is no excuse however for just banging a twig in, getting in the region of lets say 180 ohms...and then just packing tools and buggerin off...

 

[GLENNSPARK]

Playing devils advocate for a minute, what's to say it isn't deep already?

clearly not deep enough then....is it..

 

[davesparks]

What's the code for not deep enough? And should we pull it out to measure it every time we do an EICR?

Should I hand the big stirring spoon on to someone else to have a go now?