Unused SWA

[Jako13!]

What is the regs on terminating unused cable or even cores of an SWA cable. I know sometimes we can’t remove the cable completely sometimes due to being impractical.

 

[Andy78]

Unused cores or cables should be connected to earth if they still form part of an electrical installation but are unused.

 

[davesparks]

Unused cores in a cable which has live conductors in it, or unused singles in trunking/conduit which has live conductors in it, should ideally always be connected to earth. This will prevent capacitively coupled (phantom/ghost voltages) or induced voltages appearing on the conductors.

 

[Jako13!]

Unused cores in a cable which has live conductors in it, or unused singles in trunking/conduit which has live conductors in it, should ideally always be connected to earth. This will prevent capacitively coupled (phantom/ghost voltages) or induced voltages appearing on the conductors.

Unused cable all together?
[automerge]1591968359[/automerge]

Unused cable all together? So you would ideally Earth all the cores to earth?

 

[Strima]

Unused cable all together?

Yes and tied to earth. Also worth labelling up as unused.

 

[David Prosser]

I'm not aware of any regulation that requires unused cores to be connected to earth.

Most control panels will have multi core cables coming in/going out where not all cores will be used, they are not connected to earth but labelled and terminiated correctly into din rail terminal blocks.

 

[davesparks]

I'm not aware of any regulation that requires unused cores to be connected to earth.

There is no regulation specifically in BS7671. But it is common sense and best practice to make the unused cores safe, generally being connected to earth achieves this and eliminates any phantom voltage.

 

[Andy78]

I'm not aware of any regulation that requires unused cores to be connected to earth.

Does EAWR regulation 8 cover it ?

Precautions shall be taken, either by earthing or by other suitable means, to prevent danger arising when any conductor (other than a circuit conductor) which may reasonably foreseeably become charged as a result of either the use of a system, or a fault in a system, becomes so charged; and, for the purposes of ensuring compliance with this regulation, a conductor shall be regarded as earthed when it is connected to the general mass of earth by conductors of sufficient strength and current-carrying capability to discharge electrical energy to earth.

 

[David Prosser]

Many cores are left connected to din rails in control panels. I guess it would cover the other suitable means of preventing danger arising.

 

[Jako13!]

Many cores are left connected to din rails in control panels. I guess it would cover the other suitable means of preventing danger arising.

Connect in terminals or connected to earth?

 

[David Prosser]

Connect in terminals or connected to earth?

See post 6

 

[pc1966]

I would vote for connecting to earth and labelling them as spare. Generally lower R2 is always better and if they are terminated sensibly to earth they can be disconnected and used later if needed.

 

[davesparks]

Many cores are left connected to din rails in control panels. I guess it would cover the other suitable means of preventing danger arising.

Aren't these generally ELV cables rather than LV cables so the potential risk from unexpected voltages appearing on conductors is much less?

 

[David Prosser]

Aren't these generally ELV cables rather than LV cables so the potential risk from unexpected voltages appearing on conductors is much less?

Sometime but not always, it’s also 110V signals, motors and other LV equipment. For example a seven core cable but no thermistor or seal leak on the motor.

 

[R-fur]

You can also have CT and VT wiring which are not classified as ELV.
I find it varies from industry to industry, Perochem usually insist on terminating and earthing. most industries try to at least terminate. In the ESI where I do most of my work there is often just no room to terminate so they are often labelled and left in the trunking sometimes there is a separate trunking just for parking spare cores.

 

[davesparks]

Sometime but not always, it’s also 110V signals, motors and other LV equipment. For example a seven core cable but no thermistor or seal leak on the motor.

In which case they should be terminated to earth to achieve compliance with the EAWR as referenced earlier in the thread.

The fact that this is often not done does not indicate that it is correct not to do it, it indicates that a lot of people perhaps don't understand what should be done or why.

 

[David Prosser]

In which case they should be terminated to earth to achieve compliance with the EAWR as referenced earlier in the thread.

No they can be terminated safely, in preventing danger by other suitable means. As referenced earlier.

 

[davesparks]

No they can be terminated safely, in preventing danger by other suitable means. As referenced earlier.

Yes, but what is another suitable means of preventing danger?
Terminating into a terminal does not prevent the conductor from 'becoming charged' in the way that earthing it does.

 

[David Prosser]

How is a core in a cable designed to be charged dangerous if it is becomes charged? Buy being terminated and labelled correctly it can not be mistaken by a competent person (non competent persons should not be entering a MCC or any other electrical equipment without a PTW). If a fault arises it is no more likely to cause danger than if all the cores are used.

 

[Lucien Nunes]

While we're on the subject:
Socapex plug spider.