Neons on IR test .....

[jules27]

Maybe common sense ,but I'm still learning . Even if you switch the spur off will the neon still ruin your IR reading , they wont be illuminated and therefore not connected or only connected on load side.

thanks

 

[telectrix]

think you are right. if you switch off the spur/isolator, your IR tester will not see the neon

 

[jpmiff]

the neon will we disconnected ont the live side of spur/isolator so will not be seen on the ir test but will be seen on the switched side!

 

[Jimmy Boy]

As per regs in BRB you can use other methods if you can't disconnect equipment vulnerable to testing

Clamp Line/Neutral together and test to Earth

Under certain circumstances even a 250v test is acceptable

 

[swparksey]

As per regs in BRB you can use other methods if you can't disconnect equipment vulnerable to testing

Clamp Line/Neutral together and test to Earth

Under certain circumstances even a 250v test is acceptable

I wouldn't class a neon as vulnerable equipment, they are on the load side so just turn off the switch and note on your cert NEON next to the circuit.

 

[Jimmy Boy]

Are they wired between L/N or L/E ? Not all fused connection units have any double pole switch, and what if the FCU is protecting a radial or other down rated hard wired circuit ? like a small lighting circuit, you wouldn't be IR'n the whole circuit, although having re- read the OP I assume he is protecting fixed equipment so switching off would do the job

 

[swparksey]

They are wired between line and neutral. You don't need a double pole switch to isolate them.
If they are protecting a radial then you should really bypass them and complete the tests, but common sense would prevail.
3 things I hate: 1 Neons, 2 Dimmer Switches and 3 down lighters

 

[Jimmy Boy]

Your obviously a professional electrician so I can't tell you how to suck eggs, but do you not find method 2 of doing IR saves all that aggro of disconnecting Dimmers, trannys and socket based RCD's etc ?

 

[swparksey]

No because that's not how the test should be carried out

 

[Jimmy Boy]

Please explain, not looking for an argument, but to expand my knowledge of Inspection and testing.

612.3.1 BRB

Top of page 38 GN3 and page 39 GN3

Both appear to acceptable methods

 

[rocker]

There is no test between L1 and LN on method 2, and it is usually a soft test at 250V that is emloyed with this method..... I wouldn't call the removal of a neon for test purposes as unreasonable or impracticible. As has been stated switching off the switch is not necessarily going to test the full length of fixed wiring, but in the same vein testing L1 + LN to L2 is not a thorough test.

Just pull the neon, people. It's not difficult.

 

[swparksey]

Test opinion 2 should only be used when there is vulnerable equipment that can not be removed or it is impractical to remove it. Basically test method 2 is a worst case scenario, you should always do a full IR test as described in GN3, OSG, and the BRB.

 

[Jimmy Boy]

Thanks fellas I think I get the jist now

Where poss do test 1

Where not poss do test 2

However I would refer you to the NIC guidance learning course that states

" That normally IR is measured between Live conductors L/N and E, Exceptionally however for for a PIR IF it is impracticable to remove electronic devices from the circuit a measuring between to protective earth only should be made with Line and Neutral connected together.

Thanks for your input it has been really interesting, it seems on a PIR, it may be acceptable but not on a Initial or addition.

ATB Steve

 

[swparksey]

I shouldn't pay too much attention to an NIC course book, look at GN 3 and the BRB, doing a PIR would also be different from an initial verification. You could get away with method 2 on a PIR as it will be impractical to remove vulnerable equipment etc and you are looking to get a general assessment of condition in relation to the installation.

As for Initial verification you should always use method 1.

Hope this has helped?

 

[Jimmy Boy]

It has really helped fella's I plan to be top of my game so I try and sort wheat from the chaff, I ask questions not to be difficult but to challenge and get to the bottom line on the best advice, so I am very grateful of your answers and all taken on board.

Many Thanks S

 

[swparksey]

Only way to learn is ask questions bud

 

[Des 56]

Unlikely deterioration of insulation ( Pvc )
Extensive and expanding use of functional earths,electronic controls,neon lights,low voltage equipment
RCDs on most (domestic) installations
Material properties that are far in advance of what was available in the past

A sample list of why the insulation resistance test is fast becoming an un necessary or at the least, a less important test than we would be ready to accept

It is also becoming a possible "danger to equipment" test
In the near future, possibly the rule makers may have much less emphasis on this hyped up test than there is at at present

It doesn't have the importance it once did,especially initial verification
The cable insulation will either be sound or a connection or damaged cable will not be sound
Things like damp ingress into equipment, is more often than not picked up by Rcds
Low readings of insulation values are mostly confined to the likes of older installation materials


Insulation resistance ?
"remember when we used to do those tests"

 

[Jimmy Boy]

Des what an interesting observation.

How many IR's fail ?

Lets say for a board change

 

[Des 56]

I'm glad you described my post as an observation,because that is all it was meant to be
I will be clear and say that whilst the rule makers say it is important, then I will follow sheepishly

I made the post because the arguments for and against the method of doing this test,didnt mention the reasons for the test at any time

I do believe that the test is of much less importance than earth continuity or Ze or Pfc
The extreems that are suggested to carry out this test goes well beyhong what I personally would carry out for an initial verification

I believe changing a consumer unit is a different kettle of fish
By the very nature of the job,it is for older or outdated installations where the insulation resistance test becomes more important because of older materials deterioration and unknown damp and earth fault possible problems

After all its just an opinion,but also a chance to broaden the subject of the thread

 

[swparksey]

I think you should look upon an insulation resistance test on initial verification as a quality check, whilst it is unlikely a brand new length of PVC cable will have a problem, it is not beyond the realms of possibility.

Then on older installations it is a useful tool in determining the condition of the installation.