Please help, opinions advice much appreciated

[714gold714]

Hello there everybody once again

Im looking for some advice.
Basically i have an interview as a lectrurer at my local training facility and as part of my interview i have to create a presentation to year1 apparentices about earthing system in UK

So far Im completing a powerpoint presentation

Part 1
starting with the basics. What is a earth wire
Part 2
How under fault conditions it disconnects faults from circuits (about RCBOS etc)
Part 3
On to earthing system in uk eg Tncs tns tt etc basically explaining what they look like and advantages etc
Part 4
A little bit about testing eg ZE testing just very basic to keep it simple


Just looking for any advice opinions of how you would go about doing this or how i can improve this!

Much appreciated once again

 

[telectrix]

How under fault conditions it disconnects faults from circuits (about RCBOS etc).


under fault conditions, the fuse/MCB will trip due to the high value of the fault current. ( L - E ). RCDs and RCBOs are additional protection, except on TT systems where the Ze ( and hence the Zs ) is too high for OCPDs to react due to the low values of fault currents. and just to be pedantic, it don't disconnect the fault. it disconnects the supply.

 

[714gold714]

thanks mate for your reply is there anything else you think i could add as it supposed to last around ten minutes and at the moment its around 5

 

[Engineer54]

Part 3
On to earthing system in uk eg Tncs tns tt etc basically explaining what they look like and advantages etc

There is also the IT earthing system to consider. These IT systems are now the standard, for hospital operating theatres, and other medical rooms (as well as other area's in industry). so well worth a mention on the single and double fault scenario's this system operates under.

 

[telectrix]

a diagram of each earthing system showing a fault on the installation and the tracing the fault current path as part of your presentation should take up at least 5 minutes.

 

[714gold714]

This is great and exactly what I need keep the ideas flowing

thanks

 

[Richard Burns]

You could start with, but not allow it to overload your presentation, why do we need an earth and compare to unearthed systems that are also safe and why this cannot be used generally. Oh and the TNC consideration and dangers.

Discuss convenience and cost and installation for the DNOs as to why certain systems are used in certain places and how overhead supplies are earthed.