Testing extension to LED Lighting circuit

[intrelec]

I have an existing lighting radial that ends with 3 x LED downlights which are all 230VAC integral units (cannot remove bulbs).
I'm extending this by another 3 lights so I'm picking up the supply from the 3rd light and daisy chaining them up using a wago light junction box.
So how do I test this circuit?
I don't want to megger them with the LEDs in and surely the resistance readings will be influenced by the transformers inside the LED units?
If I take all the lights out and then link evrything together to test, this is a poor reflection of what will be the final installation and the only test I would be happy with would be the insulation resistance, in which case I could just test the full length of this now before I cut the newly run wire where the lights will drop from.
I could just megger them at 250V but still not sure about the R1+R2.

 

[Pete999]

I have an existing lighting radial that ends with 3 x LED downlights which are all 230VAC integral units (cannot remove bulbs).
I'm extending this by another 3 lights so I'm picking up the supply from the 3rd light and daisy chaining them up using a wago light junction box.
So how do I test this circuit?
I don't want to megger them with the LEDs in and surely the resistance readings will be influenced by the transformers inside the LED units?
If I take all the lights out and then link evrything together to test, this is a poor reflection of what will be the final installation and the only test I would be happy with would be the insulation resistance, in which case I could just test the full length of this now before I cut the newly run wire where the lights will drop from.
I could just megger them at 250V but still not sure about the R1+R2.

What has R1 =R2 got to do with an IR test?

 

[intrelec]

What has R1 =R2 got to do with an IR test?

Nothing obviously, but both tests need to be done.

 

[telectrix]

can't understand why you want to IR test. it's just a couple of added lights.

 

[intrelec]

can't understand why you want to IR test. it's just a couple of added lights.

Just for completeness on the MWC in advance of an NICEIC Domestic Installer assessment.

 

[westward10]

Link the line and neutral together at the consumer unit and only test them to earth, 500v should cause no damage. I suggest you test the circuit prior to the additions to highlight any possible existing faults, ensure the circuit has additional rcd protection if this is a dwelling.
R1+R2 can be done by linking out the line and cpc at your furthest point or the consumer unit, having fittings in circuit will have no affect to the test. Again test prior to the additions.

 

[telectrix]

so then. do the install. take L and N for the circuit out of CU. do your R1+R2 (or R2) for the MWC, then short L&N together and IR test to E @ 250V. no failed LEDs, a pretty MWC with numbers on it, a happy niceic biscuit fancier.

 

[intrelec]

Link the line and neutral together at the consumer unit and only test them to earth, 500v should cause no damage. I suggest you test the circuit prior to the additions to highlight any possible existing faults, ensure the circuit has additional rcd protection if this is a dwelling.
R1+R2 can be done by linking out the line and cpc at your furthest point or the consumer unit, having fittings in circuit will have no affect to the test. Again test prior to the additions.

Thanks - I considered this as then L&N are at same potential or on the 250V setting.
Won't the impedance be effected by the lights still in circuit?

 

[intrelec]

103.3 of the On Site Guide and 6.3.6 of the Elec guide to building regs does say that if you can't remove lamps then just test with the switch open, but then that isn't testing the insulation of any of the new wiring.

 

[westward10]

The connected fittings will not affect the R1+R2 as they will not form part of the circuit. Have all switches closed for the IR test, link line and neutral together and test at 500v. Ignore that guide and ensure you know if asked how and why you are testing in this way.

 

[loz2754]

It's all in the book:

643.3.3 where the circuit includes electronic devices which are likely to influence the results or be damaged, only a measurement between the live conductors connected together and the earthing arrangement shall be made.

643.2 where SPDs or other equipment are likely to influence the test, or be damaged, such equipment shall be disconnected before carrying out the insulation resistance test. Where it is not reasonably practicable to disconnect such equipment,... the test voltage for the particular circuit may be reduced to 250 V DC...