connectable installations shall pass a 500 V d.c. insulation resistance test between the active and each
unearthed extra-low voltage circuit. The resistance shall be not less than 1 MΩ."
Please forgive my ignorance.
What's the best method of doing this test. I just have never done IR test with power conversion equipment, battery chargers, inverters, etc and would rather check instead of potentially brake something.
For example with a standard set up as shown in attached photo. I'm sure it's common here to have elv circuit fed from battery for lights, water heater.
Is it as simple as IR test between phase and both terminals of battery?
Any thing else to be aware of?
Help appreciated
Ewof segregation
Re: Ewof segregation
Yes; it's as simple as doing an IR test between Active of the LV system and each conductor of the ELV system(s).
Basically this is the same test as used for LV circuits supplied via isolating tx.
But note the wording of the requirement: the test is only required for "unearthed" ELV (both ac & dc).
Most ELV systems have one side (generally negative for dc systems) connected to earth.
So as long as this earth reference is within the CI, and not - for example - in the towing vehicle; no test required.
Basically this is the same test as used for LV circuits supplied via isolating tx.
But note the wording of the requirement: the test is only required for "unearthed" ELV (both ac & dc).
Most ELV systems have one side (generally negative for dc systems) connected to earth.
So as long as this earth reference is within the CI, and not - for example - in the towing vehicle; no test required.
Re: Ewof segregation
an example of an unearthed ELV circuit is the ELV side of a tx / driver for ELV lights.
Re: Ewof segregation
With your example of unearthed elv light ,
if you IR test lighting circuit L-N and LED with drivers is connected you can get a short L-N, through the driver and LED
In the same way would you not get a short through some drivers or invertor phase - positive or even phase to negative though the driver or invertor. Just to clarify in this situation the circuit is fed from 230v - inverter /driver - elv
As apposed to a completey seperate elv circuit like solar panel - inverter - 1 230v power point.
if you IR test lighting circuit L-N and LED with drivers is connected you can get a short L-N, through the driver and LED
In the same way would you not get a short through some drivers or invertor phase - positive or even phase to negative though the driver or invertor. Just to clarify in this situation the circuit is fed from 230v - inverter /driver - elv
As apposed to a completey seperate elv circuit like solar panel - inverter - 1 230v power point.
Re: Ewof segregation
The test required is between Active of the LV, and the ELV circuit.
Not between A & N of the LV.
For drivers / tranformers providing ELV supply; "3000" requires the ELV to be either SELV or PELV [7.5.2].
Either way the driver / tx has to provide electrical separation between LV input & ELV output.
So for SELV there can be NO short between Active & output.
For PELV the circuit is earthed, which would create a short as you suggest; but because it's earthed this test would not be required.
Some (transformerless) inverters do have a connection between d.c. input & a.c output; but those types are not permitted as part of CIs.
Under some fault conditions this can result in the d.c. side being live at LV.
You might find them used for supplying an appliance directly, or even supplying a completely separate LV system.
But they can't be used to provide an alternative supply for the CI's LV circuits.
As defined in "4763"; isolated inverters have double insulation between input & output.
RCD protected inverters have a bonding connection between output N & d.c. input.
Equipotentially bonded inverters have at least basic insulation between input & output (and are not permitted by "3001").
Your comment:
" I just have never done IR test with power conversion equipment, battery chargers, inverters, etc" is an admission of non-compliance; as these tests are mandatory [7.5.12] for all ELV circuits installed.
Not between A & N of the LV.
For drivers / tranformers providing ELV supply; "3000" requires the ELV to be either SELV or PELV [7.5.2].
Either way the driver / tx has to provide electrical separation between LV input & ELV output.
So for SELV there can be NO short between Active & output.
For PELV the circuit is earthed, which would create a short as you suggest; but because it's earthed this test would not be required.
Some (transformerless) inverters do have a connection between d.c. input & a.c output; but those types are not permitted as part of CIs.
Under some fault conditions this can result in the d.c. side being live at LV.
You might find them used for supplying an appliance directly, or even supplying a completely separate LV system.
But they can't be used to provide an alternative supply for the CI's LV circuits.
As defined in "4763"; isolated inverters have double insulation between input & output.
RCD protected inverters have a bonding connection between output N & d.c. input.
Equipotentially bonded inverters have at least basic insulation between input & output (and are not permitted by "3001").
Your comment:
" I just have never done IR test with power conversion equipment, battery chargers, inverters, etc" is an admission of non-compliance; as these tests are mandatory [7.5.12] for all ELV circuits installed.