testing main bonds

[Lee321]

do you use any cable to hand or dedicated artic cable or some other?

do you disconnect the cable and prove the cable effectiveness or just test the connection point and/or copper pipe?

 

[Bez]

Not sure I understand the question. Do you mean testing continuity between board and extraneous conductive parts?

 

[Lurch]

I'm assuming he's referring to the testing of the continuity of main bonding conductors (in his dyslexic scouse way )

 

[binky]

Find long length of cable (I've got some singles) attach croc clip to ends (available from maplins etc) - now have long test lead at minmal cost. Attach test leads from Megger, zero leads to allow for resistance on extra long test lead - go test bonds from connection to CU or MET. I think that covers what you're asking.

 

[PC Electrics]

Lets suppose you have a house where the gas pipe is bonded okay, but the water is not bonded at all. If you merely test for resistance from the MET to a water pipe you could easily get <0.05ohms because the water pipe is connected to the MET via the boiler manifold and gas pipe (which is bonded).

It is therefore necessary to

1. visually establish that each service has a bonding point, and

2. that the cable to each bonding point is effectively connected to the MET. This is best achieved by disconnecting the bond and testing continuity between the cable end and MET (or disconnect at MET and test to each bond point).

As to what to use, well I use a length of extra flexible single purchased from Maplin. Just remember to null your meter properly before testing and un-null afterwards to prevent confusion in any other testing.

I have heard of people using a standard 'hand bag' reel extension lead. You could just use the cpc or make up connectors (using a flying socket and plug top) that use all three conductors.

 

[Lee321]

i like you lurch

cheers for the reponse lads

yeah i know how to do the test but specifically wanted to know if you disconnected the cable at the bonding point and tested that, as PC pointed out doing the test to the pipe or clamp with the cable connected doesn't actually confirm the main bonding cable as a low reading could be shown from the pipe being earthed by other means.

 

[ADS]

yeah i know how to do the test but specifically wanted to know if you disconnected the cable at the bonding point and tested that, as PC pointed out doing the test to the pipe or clamp with the cable connected doesn't actually confirm the main bonding cable as a low reading could be shown from the pipe being earthed by other means.

Disconnect the bonding from the MET, crock clip it, then test on pipe immediately next to clamp - this proves integrity of the clamp connection as well.

Doesn't matter if the pipe goes to earth then, as you're not testing to earth, you're only testing the resistance of the bonding

 

[Lee321]

Disconnect the bonding from the MET, crock clip it, then test on pipe immediately next to clamp - this proves integrity of the clamp connection as well.Doesn't matter if the pipe goes to earth then, as you're not testing to earth, you're only testing the resistance of the bonding

now thats an answer Applaud Smiley

 

[kme]

Just remember to null your meter properly before testing and un-null afterwards to prevent confusion in any other testing.

QUE?????

Un-null??

Ah! Penny`s just dropped. As in, remove the resistance of the wander lead from the nulled value. Sorry. Just looked at post and thought "summat wrong here, my tester doesn`t HAVE an `un-null`!"

:coat

 

[Risteard]

QUE?????Un-null??

Ah! Penny`s just dropped. As in, remove the resistance of the wander lead from the nulled value. Sorry. Just looked at post and thought "summat wrong here, my tester doesn`t HAVE an `un-null`!"

:coat

I suspect he means re-null the leads without the wander lead in the circuit!

 

[steptoe]

Disconnect the bonding from the MET, crock clip it, then test on pipe immediately next to clamp - this proves integrity of the clamp connection as well.Doesn't matter if the pipe goes to earth then, as you're not testing to earth, you're only testing the resistance of the bonding

very well put,

Applaud Smiley

 

[green-hornet]

Another reason for doing a continuity check on any bonding is to establish the correct resistance.

A few years ago we did a test on a 10mm earth bond, the results where very suspect, removal of a few floorboards reveiled thet the 10mm had been connected to a 4mm earth then 10mm to stop tap. so e had in effect 4M of 10mm earth connected to 12m of 4mm earth to about 1m of 10mm at termination.

If you are doing a rewire and replacing or upgrading any earthing then at least you know what is installed is what it should be. Never assume its the case if you do any PIR's though.

 

[mikep]

Wander/Long lead

We all talked about this on how to make a cheapie, here's mine at