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AMD 2 - insulation testing

AJJewsbury
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.
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  • 0
    When smart homes are in full swing, I can see that carrying out insulation resistance tests during EICRs or minor works will become practically impossible - at best you'd be checking N-E using an [L+N]=E test, as semiconductor switches or electronically controlled relays won't be "on" when you do the test.


    The idea of the test after install of a section of a wiring system is to check it wasn't "snagged" on pulling in or similar.


    After energization, any issues should be picked up by a protective device (RCD or OCPD - or perhaps AFDD).



    Electrical installations have changed over time, along with the appliances they have served, and the way both the installation and the appliances are used.


    We just need to accept that, whilst basic physics won't change, some of our working practices and designs definitely will.
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  • 0
    When smart homes are in full swing, I can see that carrying out insulation resistance tests during EICRs or minor works will become practically impossible - at best you'd be checking N-E using an [L+N]=E test, as semiconductor switches or electronically controlled relays won't be "on" when you do the test.


    The idea of the test after install of a section of a wiring system is to check it wasn't "snagged" on pulling in or similar.


    After energization, any issues should be picked up by a protective device (RCD or OCPD - or perhaps AFDD).



    Electrical installations have changed over time, along with the appliances they have served, and the way both the installation and the appliances are used.


    We just need to accept that, whilst basic physics won't change, some of our working practices and designs definitely will.
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