High ZS on new building

[WallabeSpark]

Hey, I am currently doing an apprenticeship.

I have recently followed up a few tests of some new build homes; I did one today and what has got me thinking is when I was testing my downstairs/smokes circuit, there is in total 11 lights/smokes/fans in total and 6 switches on the circuit. When I tested the R1+R2 I got a high reading of 1.57, then when I got to the ZS it measured 1.72. My incoming ZE measured 0.17 (TNCS). 

I know the measurements are within regulations, and they would trip within a required disconnection time of 0.4s, but why is it so high on such a small circuit? I have recently tested another house with downlights etc on the circuit and it was about 0.50 lower than this? 

Have I done something wrong during my second fix? can I reduce these measurements? I don't want to ask many questions to my boss as I would rather try learn this myself, incase it is something i'm possibly doing wrong then I can fix this and know for future reference.

Thanks in advance.

 

[Andy™]

most like a loose connection somewhere. do R1R2 again at various points either fro the board to the last light or last light to the board and see what the readings are, will narrow down where the fault may be

 

[Sharpend]

A combination of things, loose connections, length of cables dependant upon route, smaller diameter cable. Number of slightly loose joints over the circuit. 

 

[WallabeSpark]

I always do my R1+R2 at the end of the circuit, just kept getting the high reading, I checked the connections and did a tug test, I made sure there wasn't any sleeving caught in the terminals. I always try to take the easy routes which involves the least for less length of cable used. I just don't seem to understand why it becomes so high.

 

[ruston]

Hey, I am currently doing an apprenticeship.

I have recently followed up a few tests of some new build homes; I did one today and what has got me thinking is when I was testing my downstairs/smokes circuit, there is in total 11 lights/smokes/fans in total and 6 switches on the circuit. When I tested the R1+R2 I got a high reading of 1.57, then when I got to the ZS it measured 1.72. My incoming ZE measured 0.17 (TNCS). 

I know the measurements are within regulations, and they would trip within a required disconnection time of 0.4s, but why is it so high on such a small circuit? I have recently tested another house with downlights etc on the circuit and it was about 0.50 lower than this? 

Have I done something wrong during my second fix? can I reduce these measurements? I don't want to ask many questions to my boss as I would rather try learn this myself, incase it is something i'm possibly doing wrong then I can fix this and know for future reference.

Thanks in advance.

Is it possible your boss is testing you on this one and has introduced a fault for you to find?

 

[WallabeSpark]

Is it possible your boss is testing you on this one and has introduced a fault for you to find?

I don't believe this to be the case as he sits in his office and leaves me to fend off on the site with a labourer. Unless he is paying the labourer to introduce the faults and he is a really good liar to me then maybe. 

 

[ruston]

Ok I'm with the others then too. 

We had a boss that used to do this.

 

[Manator]

What you have to remember is that every single connection introduces a resistance, normally these would be negligible but given the amount of connections in your circuit I would say that the readings are near normal.

Remember that Zs can be calculated, so if your R1+R2 is 1.57 and your Ze is 0.17, that is 1.74, not far out from your actual reading of 1.72. No faults here and normal readings as far as I am concerned.

 

[WallabeSpark]

Ok I'm with the others then too. 

We had a boss that used to do this.

I wish my boss would do this for me, cause that way I know he's trying to get the best from me! Unfortunately he gave me the testers and believes new builds are easy tests and should be a problem, even for apprentices.

 

[WallabeSpark]

What you have to remember is that every single connection introduces a resistance, normally these would be negligible but given the amount of connections in your circuit I would say that the readings are near normal.

Remember that Zs can be calculated, so if your R1+R2 is 1.57 and your Ze is 0.17, that is 1.74, not far out from your actual reading of 1.72. No faults here and normal readings as far as I am concerned.

Yeah that is what I thought when I first realised the high R1+R2 reading, I thought I would wait until I did the ZS value just in case that was lower. My boss always told though, that if you get more than 1.50+ on R1+R2 and ZS readings on a new house then there seems to be a problem as there isn't great deal of cable runs. This is why I have been questioning myself in case I have been in fault somewhere along the line?

 

[WallabeSpark]

This is going off my main topic. I think my tutor at college wants to put my through my AM2 by the end of the year and I'm always nervous under exam conditions, especially known that AM2 is so big. Does anybody have any material that can help me with this? I ask of this because my whole apprenticeship has been spent in new houses, where its studwalls throughout and loop in from switches and well really just not much of a big experience. Which probably isn't helping the confidence of going in for an AM2. Does anybody know anyone that has done this that could shed some information for me?

 

[Sharpend]

Sorry to say and this is not a stab at you wallabe, but am I right in understanding what you are saying here. You are an apprentice yourself yet your boss leaves you on a new site on your own with a labourer? I'd suggest that it is the likes of your boss that is dragging this trade to its knees. He is probably more interested in using you and a labourer as a means of cheap labour in order to undercut other firms to get the work and at the same time letting you, his apprentice, down as you are having to bounce questions off of others on a forum rather than actually being guided and learning from him.

This is the part of the trade that the Jib, those that look at the trade through rose tinted glasses, fail to acknowledge. Disgraceful, for a technical trade.

 

[WallabeSpark]

Sorry to say and this is not a stab at you wallabe, but am I right in understanding what you are saying here. You are an apprentice yourself yet your boss leaves you on a new site on your own with a labourer? I'd suggest that it is the likes of your boss that is dragging this trade to its knees. He is probably more interested in using you and a labourer as a means of cheap labour in order to undercut other firms to get the work and at the same time letting you, his apprentice, down as you are having to bounce questions off of others on a forum rather than actually being guided and learning from him.

This is the part of the trade that the Jib, those that look at the trade through rose tinted glasses, fail to acknowledge. Disgraceful, for a technical trade.

Hey Sharpend, thanks for the response. I hear exactly what you are saying and everything you say makes sense, I've not really had much guidance from the firm they just expect me to know these things. They have me by the balls though as I have always wanted to go on to another firm that could give me better in sight and knowledge that can help me pursue into a good electrician, but I don't have the experience that I should for somebody that is nearing an AM2 level. 

 

[Andy™]

as above, you shouldnt be working on your own unsupervised yet. depending on who you work for and who the client is, you could maybe anonymously mention that there isnt actually a sparky on site. who is filling in the forms and signing them?

 

[binky]

finish apprenticeship and Foxtrot Oscar, your boos sounds like a prat. As for AM2, read, read and read some more.

 

[WallabeSpark]

as above, you shouldnt be working on your own unsupervised yet. depending on who you work for and who the client is, you could maybe anonymously mention that there isnt actually a sparky on site. who is filling in the forms and signing them?

The site that we are doing the new builds on know that there isn't a sparky on site, they have both mine and the labourers ecs cards, which state on them that he is a labourer and i'm an apprentice.

 

[Andy™]

finish apprenticeship and Foxtrot Oscar, your boos sounds like a prat. As for AM2, read, read and read some more.

that, and quit worrying about the high Zs, if it causes a problem in future itll be your boss's problem

but your most likely problem is a loose connection or 2. R1R2 at various points as i said before will narrow down where

 

[WallabeSpark]

finish apprenticeship and Foxtrot Oscar, your boos sounds like a prat. As for AM2, read, read and read some more.

I do tend to read a lot of stuff, but finding the installation side and testing of faults harder to understand from the reading as I find learning from doing something a bit easier to take in.

 

[Sharpend]

Wally what area are you?

AM2, generally it's like the driving test, pass or fail there is only a 40% chance of passing first time. However you can only prepare to your best ability, so you need to be conversant with different cables and termination thereof, you will have to know the regs and in particular the guidance note 3 for testing, not only how to test but why and what you're testing and the reason for the results that you get. Remember 40% is two in five, so if you know what you're on about and doing and why then you stand a good chance. 

 

[WallabeSpark]

that, and quit worrying about the high Zs, if it causes a problem in future itll be your boss's problem

but your most likely problem is a loose connection or 2. R1R2 at various points as i said before will narrow down where

Yeah maybe. I do put down my actual readings on the paper for him, so it is down to him if he chooses to alter them. 
 

By testing from the first switch in the circuit and moving onto the last switch be able to give me the indication of where i'm getting the high reading? I will go over all the switches tomorrow