Guys, thanks for the responses so far. My question is not for the thought of switching the neutral as opposed to the phase conductor, but in addition to. The matter was raised where generator changeover panels were discussed. I recall many years ago having something about rotating machines must not have their neutral switched. I can see the point too about the phase poles being broken marginally before the neutral, but where multiple pole devices are installed they don't always prescribe which pole is phase and which is neutral. My question is more fundamental. When we are using the three phase switching devices, when should we use four pole as opposed to three poles variants and are there any instances where the neutral should never be switched. Again, in the case of a generator and the earthed star point is downstream of the changeover, I can see the floating neutral causing issues.? ?