It may well be but you can not rely on it. You must have a full time earth.
The main bond is not there to provide the only means of connection to the supplies earth.
If you are using the main bonds as your only means of earthing then i would suggest you install a earth stake and attach it...
GU10's are NOT 12 VOLT.
neither are GZ10's
Gu and GZ 10 lamps have a max rating of 50 Watts each. they will not require high capacity switches. Ie if there is only 2 of the lamps a conventional 200 W or 5 A switch will be adequate
Scott
Im new to this forum so here goes
Yor PME earth should have been conected when the meter was put on.
If its not connected it needs URGENT attention. It will need to be connected since you can not depend on the Bonding connection to the incoming services to provide a staisfactory earth path...