testing and tails

[panny300]

i have been reading about bonding in bathrooms,and it mentioned testing with a low ohmmeter.but where do you test?is it just between the connection straps on the pipes,or is it at the taps,radiator etc.what reading is acceptable.
also what size tails should be used when someone has fitted a separate 50amp shower consumer.thanks

 

[panny300]

no one have the answers? or is there something wrong with the questions?

 

[Chivers7]

http://www.diynot.com/wiki/electric...l_bonding:supplementary_equipotential_bonding

Have a look on the wiki

 

[panny300]

thanks chivers, i understand the reason for the bonding,as my post asks,at what points do you measure to verify the bonding is doing what it is supposed too. and what size tails should be used for a separate shower 50 amp rcd.

 

[Adam_151]

This shower unit needs to contain an MCB as well as an RCD... (I hope you are aware of that if you are doing this work!)


And 16mm² should be sufficent unless the DNO insists on 25mm² for whatever reason!

 

[panny300]

thanks adam,no i am not fitting one,when i read about something i like to understand it.
wy is no one giving me an answer to the testing of bonding in a bathroom?

 

[so what if its live]

Panny

I asume you are asking about the bathroom supplementry earth bondng which should be the 4mmsq earth cable that is connected to your bathroom pipes and electrical fittings.

the reading you should obtain when testing the resistance is as follows:

R<50/Ia

R= earth resistance
Ia= is the operating current of the protectie device:
(1) for a RCD, the rated residual operateing current.
(2)for an overcurrent protective device, it is the minimum current which disconnects the circuit within 5s econd.

this info can be obtained from the electrical wiring regulation bs7671.


Alteratively, i can calculate for you. I will need to know what circuits are installed in your bathroom and what the circuits are protected by (mcb, rewirable fuse,type , amps).

When testing the resistance you should be testing the whole length of the supplementry earth cable

 

[panny300]

thank what if ,there is just the lights and an extractor (run off the light circuit) protected by a 6amp mcb.
could you explain the procedure of how you actually test to check the bonding please.

 

[panny300]

anyone

 

[Adam_151]

Continuity test between earth conductors of cables serving equipment in the bathroom and extraneous conductive parts, along with a visual inspection of the bonding

 

[panny300]

thanks adam, very helpful,so how would you test that the bonding between the various items in the bathroom ie taps radiator towel rail etc is effective if the bonding was done in a cupboard next to the bathroom.

 

[ebee]

Use an approved low ohm continiuity meter.
Measure between each of the following :-
pipework (Hot, cold & CH) if metal and CPCs (circuit earths) .
You are looking for 0.05 ohms or less .
Hope that helps

 

[panny300]

very helpful ebee, thanks