high Ze

amckay · Aug 8, 2015

Hi guys. I was periodic testing a site the other day and came across a Ze of .40ohm. Supply (I think) its tncs (in the cutout there was only L&N supply cables (street lighting LUCY cutout where you can easily see the DNOs N & E cable terminations)).
Now I know the Ze is nothing we can really do anything about, but my boss (all the supervisors and managers in my firm know nothing about the trade) doesn't seem that concerned, and to be honest I'm not sure whether I am or not because I've not come across a Ze that is over the recommended values until now.
I have put down on the certificate that I reccomend referal to DNO but other than that I'm not sure what I can/should have done and what the DNO would say/do

telectrix · Aug 8, 2015

as long as your Zs values are within limits, worry not.

Plonker 3 · Aug 8, 2015

amckay said:
Hi guys. I was periodic testing a site the other day and came across a Ze of .40ohm. Supply (I think) its tncs (in the cutout there was only L&N supply cables (street lighting LUCY cutout where you can easily see the DNOs N & E cable terminations)).
Now I know the Ze is nothing we can really do anything about, but my boss (all the supervisors and managers in my firm know nothing about the trade) doesn't seem that concerned, and to be honest I'm not sure whether I am or not because I've not come across a Ze that is over the recommended values until now.
I have put down on the certificate that I reccomend referal to DNO but other than that I'm not sure what I can/should have done and what the DNO would say/do

as tel said there isnt alot to worry about as long as your Zs values comply.

who is your mentor/ qualified electrician who you are working under at work? I only ask as you are a trainee and want to ensure you are being taught by the correct people?

malcolmsanford · Aug 8, 2015

amckay said:
Hi guys. I was periodic testing a site the other day and came across a Ze of .40ohm. Supply (I think) its tncs (in the cutout there was only L&N supply cables (street lighting LUCY cutout where you can easily see the DNOs N & E cable terminations)).
Now I know the Ze is nothing we can really do anything about, but my boss (all the supervisors and managers in my firm know nothing about the trade) doesn't seem that concerned, and to be honest I'm not sure whether I am or not because I've not come across a Ze that is over the recommended values until now.
I have put down on the certificate that I reccomend referal to DNO but other than that I'm not sure what I can/should have done and what the DNO would say/do

I'm getting quite concerned here for you son, I'm not quite sure what the set up is with you but why as a trainee are you carrying out EICRs and to be honest not being able to understand what kind of system you have, what kind of results you should be working to.

I'm guessing because you think it is a TNC-S your result should be 0.35 or lower and in most cases it will be. But that is normally just a guide and you are working on Street lighting with greater distances involved with cable runs so you might find your Ze could be elevated to above that figure. Also remember the ESQCR-2002 doesn't give a recommended value for a PME, just that is needs to be stable. It is a guide the 0.35.

Don't think I'm having a go at you far from it, but as I said I'm genuinely worried for you. If you are carrying out EICRs then you are the one that is confirming that the installation is safe for further use.

GMES · Aug 8, 2015

I am with the guys here Amkay regarding being concerned, in my eyes any Electrician should have a minimum 5 years on the tools before they even consider attempting inspection and testing. There is a reason it used to be considered the hardest qualification to achieve.
Who is guiding you if as you say your boss and supervisors don't know what they are doing.

I don't like to think of anybody being out there trying to do a job they are not ready to take on, and that's not a pop at you it's concern for you.

amckay · Aug 9, 2015

Hi guys, I appreciate the concern you share and I genuinely think you all have a valid point. Just to clarify the Zs did comply (can't remember what the value was off the top of my head now).
I work alone. There is a "team" of 5 sparks in the place I work (advertising company operating in 30 countries worldwide) one works predominantly on billboards, one predominantly on digital installs, 2 predominantly on bus shelters but lend a hand elsewhere 5% of the time, and me who works predominantly on bus shelters but also digital 20% of the time.
One of the sparks who works here is about 50ish and been in the trade on various works since his apprenticeship at 16. I was twinned with him for the first three months to get a feel for the type of work and get used to how the varying types of sites work etc. (I've been here 6months now) he is very confident in my abilities. I myself am confident but lack some knowledge in testing. Have previously done commercial and domestic works.
My background (just to clarify)
I'm 28, and I retrained about 4 years ago at a tech college doing 2330 (which was Monday to Friday 9-5 for six months, mixed classroom and workshop with the tutor being a a time served spark) after which I worked as a mate on domestic until I got 2382, 2377 and 2393. Then I worked as a spark on commercial (took 2394+5 but failed written) and currently half way thru my 2356NVQ3 with XS training. then I came to work at current firm as its cards in. All courses are C&G and in no way are Electrical Trainee courses, all courses undertaken have been paid for by myself (no gov funding for over21s).
I wish I had continued with my college apprenticeship at 16 but stuipdy dropped it to join the RAF which clearly didn't turn out to be a lengthy career lol
Sorry for the waffle but I wanted you to know the full picture.