Earth in lighting circuit? Connect LED bathroom mirror?

[rarara]

OK, try not to complicate things...

1) The light switch in the bathroom has live and neutral connected, and the earth visible but just hanging loose behind the fascia. Is there an easy way to test if this earth cable is actually earthed back at the consumer unit? Why if it is would this not be connected to the earth point of the patress box as a matter of course?

2) Am looking to install an LED bathroom mirrored cabinet - the position is close to the light switch (nothing else is remotely nearby). Is there any reason (assuming the answer to Q1 above is that the earth is valid) why not to take a spur from the light switch itself?

 

[ban-all-sheds]

OK, try not to complicate things...

1) The light switch in the bathroom has live and neutral connected,

No, it doesn't.

It has live and switched live. If it had L & N there would be a ^&*£$)#@~€ great bang when you turned it on, accompanied by exciting flashes, destruction of switch, blowing of fuse/tripping of MCB etc.

PLEASE take some time to learn how lighting circuits work, what switches do, how things are wired up etc BEFORE deciding to fiddle with things.

• http://www.google.co.uk/search?q=electrical+circuits+(basics+OR+101)
  
  
• http://www.google.co.uk/search?q=uk+house+wiring+(basics+OR+101)
  
  
• //www.diynot.com/wiki/Electrics:Lighting
  
  
• //www.diynot.com/wiki/Electrics:books

and the earth visible but just hanging loose behind the fascia. Is there an easy way to test if this earth cable is actually earthed back at the consumer unit?

Yes, if you have a low-ohm meter and a long lead.

Why if it is would this not be connected to the earth point of the patress box as a matter of course?

Wired up by a numpty?

2) Am looking to install an LED bathroom mirrored cabinet - the position is close to the light switch (nothing else is remotely nearby). Is there any reason (assuming the answer to Q1 above is that the earth is valid) why not to take a spur from the light switch itself?

Yes - it won't work - there's no neutral there.