IR testing

[Traineeboy]

If a lighting circuit has like 20 down lights with non removable bulbs on it and you are carrying out an IR test do you have to take every Downlight out the ceiling to disconnect them ? Or is there another way.

 

[Sidney]

Initial verification or existing installation such as a periodic inspection?

 

[Traineeboy]

Initial verification or existing installation such as a periodic inspection?

if say your doing a minor works by adding a new light . You need to test the circuit the new light is going on but there loads of downlights on that circuit. 

 

[boltonsparky]

GN3 chapter 2, bottom of page 50 continuing onto page 51,

"Where the removal of lamps and/or the disconnection of current using equipment is impracticable, the local switches controlling such lamps and/or equipment should be open. An insulation resistance test of L&N connected together to E will ensure that all circuit conductors are tested"  

 

[Traineeboy]

Just so I’m understanding this correctly...

if lamps etc can’t be removed if I test at the board live - live (L-N) and then test live -earth  (L+N to earth ) and the light switches are off then this won’t damage or affect the test ? 

 

[Risteard]

Just so I’m understanding this correctly...

if lamps etc can’t be removed if I test at the board live - live (L-N) and then test live -earth  (L+N to earth ) and the light switches are off then this won’t damage or affect the test ? 

The switches should be closed for the Live/Earth test. It's referring to Live/Live with switches open. Personally I'd probably only do Live/Earth in those circumstances.

 

[SPECIAL LOCATION]

New installations..   Test fully between all conductors with loads disconnected so you can be 100% sure none of your new cables have been damaged.

Existing installations, more often than not it is totally impractical to disconnect all possible loads...  assuming you know where they all are!!!

Unless of course the customer is willing to pay you loads of money for the extra time expended!

So banging 500v DC between Live & Neutral could potentially Zap some vulnerable equipment you are not aware of...

An IR test at 250v between Live & Neutral can be done to give you an indication of potential loads connected or problems if the loads are actually all off.

But leaving Earth still connected at the CU..  and joining L+N together... 

to test at 500v DC  between (L+N) to (E) will verify the insulation is good between all live conductors and earth...

Personally I often do a low resistance continuity test between L & N to see if there is anything bleedin'-obvious still connected!

This problem is also common with some old decorative chandelier, or wall light fittings,  or outdoor weatherproof lanterns etc..

You could end up damaging a customers decor or light fitting if you need to start removing all loads just because you have added one new light onto a circuit!

Guinness              

 

[Traineeboy]

Thanks guys appreciate it. My Tutor did a poor job on explaining that. I get now thanks for your input.