Very high r1+r2 readings and Zs in conduit?

[Kev2632]

Hi,

Why would I be getting very high r1r2 readings and Zs readings in a water heater circuit wired in the existing conduit when the house was built back in 19oatcake...? Would the conduit have anything to do with it and if so? Why?

Thanks

 

[VoltzElectrical]

loose connection somewhere?

 

[WPD Lad]

Immersion heater?

 

[trev]

Not enough info to make a judgment Kev. What's the earthing system/Ze/Zs readings on other circuits/have you recently installed an RCD etc etc etc

 

[Kev2632]

All my other circuits readings was good, tn-s system, all connections are tight, and disconnected the water heater supply side from the switch and was still getting weird readings??

 

[VoltzElectrical]

JB somewhere? dunno, just clutching now.

 

[trev]

If it's been wired donkey's years ago I'd be thinking of a JB somewhere.
Is the conduit your CPC?

 

[Kev2632]

Nope no jb, would the badly made off conduit end or something affect the readings for r1r2 and Zs?

 

[Kev2632]

Yea just the conduit as my cpc, and no JB's anywhere

 

[trev]

A jb could be under a floor, if the conduit is your CPC then a poor loint could be to blame but like Voltz said, I'm clutching a little here

 

[Kev2632]

Yea, what ya mean your clutching?

 

[sedgy34]

kev,
sounds like you have a break in the conduit joint ive had similair problem before in a church make sure you completely eliminate the swith from the circuit too

 

[Kev2632]

Yea that's what I'm thinking too, yea I elminated the switch from the circuit so I only had my live coming in from the consumer unit, and tested to the earth on the backpack where the conduit came in, you know?

 

[VoltzElectrical]

how high are these readings? I mean that would have to some pretty badly made off conduit.

 

[trev]

Yea, what ya mean your clutching?

Clutching at straws mate. One of my many skills

 

[sedgy34]

great minds think alike forget all other responses with jbs etc (lol) JOKE!!!!

 

[Kev2632]

I was getting 200ohms+ everytime ??? :/

 

[sedgy34]

how high are these readings? I mean that would have to some pretty badly made off conduit.

this problem has probably happened when some renovation works have been carried out without messing with the electrics

 

[VoltzElectrical]

can u uncover any conduit boxes and try pulling on the cables. Surely the benefit of conduit wiring is that it can be rewired easily? May be possible to pull a cpc in?

 

[Kev2632]

with the CSA of the conduit in which its wired, will that allow it too have such a high reading? or would that normally give a very low reading if the conduit is " sound", because the CSA area is bigger so it should in theory have alot lower reading than the R1+R2 of live to earth in twin and earth yea??

 

[VoltzElectrical]

you could check to see if the fault is on the live by doing an R1. We're assuming here the fault is on the earth, but that is only one half of the story given the tests conducted?

 

[Kev2632]

yea i'll give that a go, but would the CSA of the conduit have anything to do with it? or would that normally make the readings alot lower yea? is that right?

 

[VoltzElectrical]

Is the conduit earthed correctly at the consumer unit? Does the consumer unit connect into the conduit? is the consumer unit plastic by any chance? Are all the other circuits earthed using the same wiring method?

we are all sat at home in front of keyboards with a beer cos nothing is on TV.

We need the maximum amount of info if we are to help.

AND, when you do get it sorted, come back on here and tell us what the problem was so we can all learn!

 

[VoltzElectrical]

yea i'll give that a go, but would the CSA of the conduit have anything to do with it? or would that normally make the readings alot lower yea? is that right?

Conduit earthing would normally make it lower, unless there is a plastic section in it! Or is it all plastic?

 

[Kev2632]

nah its all metal i think to be honest like.

 

[VoltzElectrical]

even the dis board?

Take a wander lead from MET to all accessible points and see where breakdown or errant readings start.