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Silver : is the most Conductive Material . it’s Price . etc .
Copper ; is the Second most Conductive Element . ( Copper as the Best Alternative )

( Plain English Simplified ) Theory Behind : ( V + / - ) → ( I ) ( R )

( V ) = Voltage ( Pressure behind Current Flow )
( I ) = Amp’s ( Flow of Current )
( R ) = Ohm’s ( Résistance or how much Current will flow Through a Component )

High Voltage moves a Large Current .
Low Voltage moves a Small Current .
 
A Fundamental Question .
Will the Protection Device Function ?? During a Fault Condition ?

- Let’s consider the Difference between Fault Level Current Rating & ( PSCC ) Prospective Short Circuit Current . the Fault Level Current Rating can be seen on a ( MCB ) Circuit Breaker . Example as 6kA . ↔ This means that the ( MCB ) is able to “ Withstand up to 6000 Amp’s for a Short Period without being Destroyed . ( Tripping Time depends on the MCB )

( PSCC ) Prospective Short Circuit Current . measured in an Installation is used to Consider whether the Circuit is Capable of Carrying sufficient Current so as to Trip the Overload Device in the Specified Time .

High values of ( PSCC ) Prospective Short Circuit Current . can vary Dramatically due to small changes in Impedance . ??
V = Z x I
Example : I = 230 / 0.03Ω = 7666. Amps
Or : I = 230V ÷ 0.01Ω = 23000 Amps

Notice : The vast change in Current for a very Minor Difference in Impedance , ( Low Impedance is very Difficult & High Current is Required )
 
Re: PIR reporting and competent persons.

“Apprentices “ Useful Junk “ BS-951 ( We Use this Day in & Day Out without thinking about it ) Yeah . All in a Word

Specifies the performance and important Mechanical requirements for metal clamps that are used to provide Mechanically and Electrical Sound earthing and bonding connections to metal tubes. The information . relates to the correct selection and installation of such clamps within electrical installations.

Misuse of BS-951

Cases of misuse of BS 951 clamps are occasionally found, some examples of which are given below. ( You will see this in your Travels ! )

Fitting a BS-951 Clamp to the Armour or Metallic Sheath of a Cable ( the Why’s !! )

BS 951 states that clamps to this standard are Not intended for connection to the armour or sheath of a cable and requires the packaging of the clamp to include the warning “ Not intended for Use on the Sheath or Armour of a Cable “. This is because the Action of tightening the clamp is liable to damage the cable, for example by crushing the bedding or insulation or by causing the metal in a lead sheath to Cold – Flow . Such damage may result in High Résistance and unreliability in the electrical connection between the clamp and the armouring or metallic sheath, and may even result in an electrical fault within the cable, Fitting a BS 951 clamp to the armour or metallic sheath of a cable is therefore Unacceptable .

Fitting a BS-951 Clamp which is Unsuitable for the Pipe Diameter & / or Cable Size :

A BS 951 clamp must be correctly selected for both the size of pipe or tube to which it is to be fitted and the size of cable. Fitting a clamp which is unsuitable in either of these respects is liable to be a departure from the requirements of Regulations 526.1 and/or 526.2 of BS 7671 relating to durable electrical continuity, adequate mechanical strength, and appropriate selection of a means of connection.

● To avoid corrosion due to electrolytic action, Aluminium Labelsof BS 951

Installing a Clamp in an Inaccessible Position :

Like all types of electrical connection that are not excused by Regulation 526.3 of BS 7671, the electrical connections between a BS 951 clamp, the pipe (or other tube) to which it is attached, and the protective conductor connected to its terminal must be accessible for Inspection , Testing and Maintenance (Regulation 543.3.3 refers).

BS-7671 Requirements ! ( The Only Trouble with the Regulations . they are all Scatted to the 4 Winds )

Warning notice-earthing and bonding connections ( 514.13 )
External influences (Section 522 )
Connections between conductors and a conductor and equipment (526.1)
Accessibility of connections (526.3 )

Résistance to Corrosion :

Clamps to BS 951 are made in a choice of different metals, to suit differing levels of corrosion that are likely to be encountered in service. In order to comply with the requirements of Section 522 (Selection and erection of wiring systems in relation to external influences) of BS 7671, it is important to select a clamp which is suitable for the expected conditions in the particular location where it is to be installed. For example, some clamps are intended for use only in dry conditions, whilst others are suitable for damp locations such as bathrooms. Some manufactures of clamps use different colours to indicate the type of application and environmental conditions for which the clamp is intended, similar to the colours shown in the illustration below. Where doubt exists as to the suitability of a clamp for use in a particular environment, advice should be sought from the manufacturer.

Terminations :

The termination on a BS 951 clamp for the protective conductor is separate from the means of tightening and locking the clamp for making electrical contact with the tube.

A screw termination is capable of accepting one of the following: Etc .

● a conductor clamped under a screw head provided with a captive washer so that the screw head does not act directly on the conductor; Etc.

“ Phil can this be move this to the Right Place “ Please . Thank you . Amber . :) Ta.
 

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