Earth fault loop testing at furthest point

[muckychimney]

Heres one. Over on another forum a poster has said that when doing loop tests they always test at the furthest point - which is correct, however they then go on to say that if they were testing a water heater circuit they would test at the connection point on top of the heater rather than at the spur / isolator.

From what I was taught when I was an apprentice, I was only taught to test upto the final connection point on the installation of the fixed wiring thus being the spur or isolator, and not to include the flex to the heater as that isnt part of the installation.

In effect if you go by the way this other person is testing you could say if you plug a 50M extension lead in then that would be the furthest point would it not, but in testing that your readings are going to be way out ? Take the immersion heater, 1.5mm HR flex - wired in 2.5mm t&e on the installation, two different cable sizes for a start, not a lot of difference in the resistance but surely that would be wrong to test that way.

 

[telectrix]

either way is correct, IMO. the flex is part of the fixed wiring by reason of being hard wired into the FCU/isolator. anything with a plug on it ain't.

 

[trebor]

This is an interesting one which could have more than one correct answer depending on for example the type of test initial or pir, whether the spur is fused or not, I agree with telectrix in so much as long as the value is within the tabulated requirement then ok, but the interesting point is the new 2394/5 which on a certain circuit is looking for you to eliminate parallell earth paths via the plumbing as part of the practical assessment both on initial and pir

 

[Jimmy Boy]

Where would the other poster take the R1+R2 ?
J

 

[trebor]

At the control switch after disconnecting the supplementary conductor from the circuit