Bs 951 bonding clamp

[mainebankelec]

Been to a property for yet another PIR yesterday and would like to guage other peoples opinion on this one.

Incoming NIE supply cable is supposed to be TNS but the earth at present is fed from 2 951 bonding clamps. My query is on this i have now been advised by NICEIC to fail the installation as its code 2.

I must now report to customer that it fails and to fix this i have been advised to install earth rod and make it TT, this means yet another RCD up front as there are two metalclad consumer units in the premises. Then inform the customer to contact NIE to have them come out check the supply and if they are happy with a 951 clamp get them to issue this in writing and attach to certificate.

Ze at present 0.13 ohms 1.7KA L-E 2.4Ka L-N

 

[telectrix]

are these BS951's on the sheath of the incoming cable?if so, it's the DNO's responsibility to maintain the earthing arrangement and are obliged to put it right.

 

[mainebankelec]

yes on a lead sheathed cable. Was informed by other spark in northern ireland that NIE will take no responsiblilty and inform to TT anyway. What would you do on periodic report concerning this? BTW the is to be a rental property and cannot be 100% sure tenant will not tinker lol

 

[Guest123]

A BS 951 should never be attached to a supply cable as the supply cable is the property of the supply company and it will also damage the insulation of the cable and over time it will loosen with the cold flow of the lead.


It even states in BS 951 that these clamps should not be attached to any sort of electric cable.


Reg 512.1.5 is about the closest I can find.

 

[gap30]

A BS 951 should never be attached to a supply cable as the supply cable is the property of the supply company and it will also damage the insulation of the cable and over time it will loosen with the cold flow of the lead.


It even states in BS 951 that these clamps should not be attached to any sort of electric cable.


Reg 512.1.5 is about the closest I can find.

This is something i have done many times in the past on a tn-s, how do you get around this? usually there is a bit of copper about 2.5mm going to a connector block if its really old - do you have to contact the DNO?

 

[malcolmsanford]

Though the guys are all correct the majority of the time, if this wasn't a DIY TN-S done by a spark, the old DNO guys use to use BS 951 clamps as the spring retaining clamp was either not available or too expensive, but now with TNC-S system the TN-S is normally 20+ years old.

If you find one of these with just a 2.5mm cable from the clamp to an MET the first thing I would do is a Ze to see what your external fault path was. Depending on that result would guide me on my next step.

 

[gap30]

sometimes its just easier to put a clamp on, depends on the situation as you say, but you get so used to seeing clamps on them you end up following suit which may be wrong - i always assumed this was ok, besides its usually ten times better than whats already on

 

[gnselectricals]

I would'nt put a code 2 down as its not our reponsibility and not something i look at on a PIR as long as Ze is good then that should be ok.
Also that the tenant is going to mess about with the electrical installation is up to them, should anything happen it would be on them rather than you.
regards gram

 

[malcolmsanford]

sometimes its just easier to put a clamp on, depends on the situation as you say, but you get so used to seeing clamps on them you end up following suit which may be wrong - i always assumed this was ok, besides its usually ten times better than whats already on

The last thing I would be doing is fitting another clamp to a lead sheathed cable that could be , well years old.

I would as above do a Ze and depending on that and your PFC calcs, decide the course of action to take.

 

[mainebankelec]

In regards to not code 2 it I have been advised by Niceic technical helpline that it has to be code 2. In my eyes but a code 3 would be suffice as it requires further investigation by others eg Nie deeming it satisfactory? Could I code 2 it and note on certificate that If supply authority issues written statement then the certificate is deemed satisfactory?