Electrical Safety

Mark GoughElectrical InspectorNorthern Specialist Group

Topics Covered Duties of Inspector Generation Distribution Case Studies

Duties LEGAL prevent danger to your self and

others affected by your undertaking.Recent case inspection company fined £200 000 and possible manslaughter charge

Moral to ensure safety Fairground Operators and members of public

Economic Comprehensive inspection and testing is a skilled job and takes time.FFI, loss business you and operator, PN’s IN’s Fines, court costs etc all uninsurable

Fairground Generation

Generator or transformer

Star Point

Brown Phase

Black Phase

Grey Phase

Neutral

Earth (Circuit Protective Conductor)

400V

400V

400V

230V

230V

230V

Note 5 conductors Essential

230 V50 Hz

If you touch the ride with fault and adjacent metalwork what will happen

Oooerr!

Generators with 4 conductors

230 V50 Hz

Current flows from the supply, through the fault, through herand back to the supply via earth.

Aaagghhh!

Protection against Indirect Contact

230 V50 Hz

What happens when I introduce the same type of fault as before?

Protective Conductor

Fuse

If you add an earth conductor 5 wire system

230 V50 Hz

Protective Conductor

Fuse

It’s determined by the voltage and the ‘Earth Fault Loop Impedance’‘Earth Fault Loop Impedance’ – a very important system parameter. If it’s too high not enoughcurrent will flow to blow the fuse quickly enough to prevent danger.

Protection against Indirect Contact

230 V50 Hz

Fuse

Not Again!!

Here the fairground owner has joined the neutral and earth.What Would happen?

Protection against Indirect Contact

230 V50 Hz

Fuse

Oh for GoodnessSake!!

Here the return is damaged The exposed metal work of the ride could become live. If the return is damaged

Protection against Indirect Contact

230 V50 Hz

Protective Conductor

Fuse

Now let’s introduce a ‘bonding’ conductor that connects the exposed metalwork together.

Protection against Indirect Contact

230 V50 Hz

Protective Conductor

Fuse

Protection against Indirect Contact

This is cleverstuff. I wishI could be anElectricalEngineer.

We have here the concept of Earthed Equipotential and AutomaticDisconnection of Supply (EEBADS) – the fundamental safety systemin the UK for protection against indirect contact electric shock.

At Generators Check 5 conductors (no more or less)

Do an earth loop impedance test or earth to neutral continuity

Fused correctly working 100mA RCD?

Earth spike? Preferable not as important as earth neutral continuity test

What can be done including 30mA RCD

Distribution 30mA RCD sockets and

lighting Suitable plugs Short runs Damaged Cables Overloaded Circuits

Recap Generators 5 core AND earth

neutral continuity (ELI test) 100mA RCD time delayed Final circuits 30mA RCD BSEN 603092 plugs / sockets Encourage use of plug in

testers

Competence Costs BUT

Incompetence Costs More