Looks like the DPC has made a bit of a change about insulation testing where some devices might be vulnerable to a 500V test voltage or distort the results. Previously we were allowed to either disconnect the item concerned (or do the test prior to initial connection) OR carry out a 250V test (with a 1MΩ limit to meet).


As I read it, a full 500V test will soon be required prior to connection of such equipment PLUS an additional 250V test (with a 1MΩ limit to meet) will be required after it is connected.


I can see the sense in that, in that it doesn't 'excuse' the rest of the circuit from a full 500V test, but I'm slightly uneasy about some equipment not being happy with a relatively long duration 250V d.c. test L&N - PE - especially if it has to meet a 1MΩ limit. Does anyone have any thoughts on that?


All strictly speaking for an initial verification - for a periodic we still seem to have the flexibility of choosing 'appropriate' tests (however that's going to be interpreted...).


Seems it's going to be a bit of extra work, especially if you've a house full of USB power sockets....


   - Andy.