Recently, a fellow club member said he couldn't fathom out how to wire up a 2 button on/ off switch box for a machine. His expertise lies in mechanical engineering, not electrical.

These black and yellow plastic boxes are sold in the UK with a circuit diagram. The much cheaper far east version is identical but no circuit diagram is supplied and the inner black terminal block appears to have different internal connections so UK version circuit diagrams don't work.

The 3 button boxes that have a red mushroom head emergency stop, have a second smaller black terminal block inside, for the emergency stop. Instead of the live mains feed being connected to a certain terminal on the two button block, the same terminal is fed from the output of the smaller emergency block. The input of the smaller block is fed from the live mains wire. It can therefore be seen that the emergency button is connected between the live mains and the larger 2 button on/off switch block.

HTH anyone with the same problem.

John