Ze & Ipf by enquiry

[jay_t]

Does anyone actually use the 'by enquiry' method for finding Ze of Ipf? If so, who do you talk to??

I have tried to obtain the value for a property to compare it to my measured values and keep getting sent round in circles from the DNO to the supplier and they tell me that neither hold values for individual properties, they can only tell me maximum values for specific types of supply (well, duh!! I've got a red book too!!)

I've given up now, don't really need them for this job anyway but it got me thinking, has anybody ever successfully enquired about these values?

 

[Andy™]

By enquiry usually gets the the max value. if you want anything more specific, you gotta test it yourself

 

[GreekIslandLover]

Never even tried to obtain a value. Always measured it.

 

[Andy™]

Never even tried to obtain a value. Always measured it.

same here. even if they did have the exact value on their computer, it should still be tested on-site to make sure there is an earth. been to quite a few places with TN-S lead cable, and found reading has been high (many 10's) caused by an open joint somewhere. by enquiry wont find that!

 

[Evans Electric]

I've never understood the " enquiry" thing either. As Andy says they just give the maximum value. Where I live in North Birmingham and also the Sutton Coldfield area, the earthing on the TN-S supplies is getting worse with the continuity breaking down across the cast iron joint boxes in the ground. You have to test them !

deke

 

[Andy™]

TN-S supplies is getting worse with the continuity breaking down across the cast iron joint boxes in the ground. You have to test them !deke

can even get different readings on different days in some places

 

[Robojin]

I got 0.17ohms ELI, but that was cause the DNO was there to upgrade the supply head

Also they had to get a crew in to dig a hole in the front lawn and cut the cable cause of HSE rules, after they went back came another crew to fill in the hole

 

[Janice]

Measure it. If your meter is still in one piece afterwards, you probably don't own a Kewtech.

 

[Tarpole]

I used to work for MANWEB we used to hold values for most areas, thats in the good old days pre privitisation. You can still get values for larger Commercial property. They are normally used for designers.

JUST TEST IT (correctly) and use a fluke (non explosive type)

 

[jay_t]

Cheers guys, I always measure anyway but, as andy stated above, different readings on different days..... i get that - i do a lot of maintenace work at a particular school and the Ze is quite often different...... not drastically, but that's what made me think i'd enquire as to the value the supplier/dno held, but obviously they don't hold a value any more.

 

[M107]

Just use the max values for the cert, but I also measure & put these values in the comments box on the cert.