Bosch Cooker hob Operating Instructions Manual page 7

Fig. 2
Fig. 3
Fig. 4
B
A
6
This new and innovative appliance has a general gas cutoff
system - Main Switch - which, if there is
an emergency, allows the gas flow to be completely cut off.
Using Main Switch:
When using the appliance under normal conditions, the Main
Switch button should not be pressed down Fig. 2., but if a need
should arise to suddenly cut off the flow of gas, whatever the
number of burners currently operating, you simply press the
Main Switch button and the hob will be completely blocked.
Fig. 3.
To unblock the hob:
T
Press and turn the Main Switch button clockwise as far as it
will go. Fig. 4