IR test whats the point?

[telectrix]

5 horse. thats the bhp of my van.

 

[Deleted member 9648]

If you cant be bothered to IR test how many other tests cant you be bothered to do?

 

[telectrix]

he's just been offered a job at newbury.

 

[mayfair]

stuff it let em fry lol

If you cant be bothered to IR test how many other tests cant you be bothered to do?

 

[nickblake]

Old timer ,Malcome ,and tony MC's comments are spot on , Ask the same question to a family who's house has just burnt down , ill give you a couple of examples of why we do it , Recent fault ,on a post i put up RCD tripping at 10.30 every friday in a pub , switch it back on fine not problems , testing the circuit indicated a low IR between L and N , the fault turned out to be a rat chewed cable getting damp due to condensation could easily have smoldered and caused a fire , 2nd example MCB tripping Reset all ok, every so often it tripped ,testing the circuit showed a low insulation reading between all conductors disconnected all lights and just ended up with open cables still low IR, fault was located to a covered joint in a plaster board ceiling ,it had been plastered over , this had caught fire but due to the wood being chip board it extiguished its self if it was wood then there would have been a major fire , this is why we do IR tests as well as has been mentioned to monitor the condition of the installation befor it causes major problems , that could risk lives . below are some picks of the fault mentioned above where the wood caught fire look at the picture with the square hole cut out you can see the burnt wood ,That is why we do IR tests simple as !

 

[malcolmsanford]

Top class post Nick .................you and the pictures say it all mate.

 

[simpson93]

what is the point of an IR test? yes i know its to show low risistance on cable insullation [its in the name] and that can lead to short circuit and fire risk, but with the protection we use now wont this show its self eventually. what do you tell a customer in a nursing home ? that his IR is a bit low and some time in the future he may get a problem. HE says when,and you say,i dont know,he says,what,and you say,i dont know. AM i the only one who thinks while IR testing with all the ******* hassle that goes with it. WHATS THE POINT

with the protection we have now why test at all?
what your basicly saying mate is why dont you just bang test it?

 

[telectrix]

nice pics, nick.hope you stripped it back well and used wagos before platering it back in.

 

[nickblake]

nice pics, nick.hope you stripped it back well and used wagos before platering it back in.

The joint in the picture was twisted to gether with selotape over it , it now has a ashly J501 on it got a 2 gang blanl plate and glued and scred it to the ceiling with some intermesant sealant ,here's a pic of the other light twisted together , what we found whilst trying to locate the fault

 

[SirKit Breaker]

There are several reasons for IR testing, aside form all the previous answers including Telectrix

When the IR starts to get low it will induce voltage/current into the CPC. Once it gets down to about 1meg it can start to have an effect on the circuit protection to the point that enough current and voltage will be induced for the RCD to see it and start tripping off, and the safe touch voltage can be reached. Hence 1 meg is deemed to be the minimum IR value for domestic 230v circuits, and investigation is advised under 2 meg.

Widdler teaches 2391, he can probably explain it better than me.

Cheers..........Howard

 

[mart1711]

Surprised a contractor asked the initial question to be honest. When RCD's first became widely available, i think (by the manufacturers propoganda somewhat) they were heralded as the easy fit life saviving must have electrical item, and surpassed any other measures of protection and quality installation. All the tests are important and for a reason. I went to look at a fault on a lighting circuit in a local corner shop just the other week. The owners had added bits a pieces of their own over time with choc blocks and pvc tape etc. A fault had arrisen on the circuit (protected by rewireable fuse) and caused the cables to overheat and smoulder, then after creating a short pop the fuse. I showed the problem to the owner and how it was caused, to which i got this EXACT response "Can we just stick an RCD on it??"

 

[oldtimer]

(by the manufacturers propoganda somewhat) actually Mart RCDs were introduced to get us in line with Europe (yep that old chestnut) so the only thing left is the ring main, the 13 amp socket and to get the light switch to work when up not down.

Mind you the more I am reading this thread the more I am amazed why the question was asked in the first place

 

[bugsy]

Yea lets stop doing I/R oh sod it why bother with continuity - i will either work or not , thinking about it anybody wanna a buy fluke MFT ,Im gonna get a socket and see a nice neon and volt stick - what a saving

 

[nickblake]

RCD's are not the be all and end all they fail and regularly too , i may be a bit old school , but i do like to sleep at night , when i carried out my 2391 the routing of testing was drummed into you , i will always do my ring continuitys R1 & R2 tests and IR followed by the Zs , then if applicable the RCD tests , i will test the R1 & R2 tests at several points , just to confirm the polarity is contiuose ,What is the point of testing if you skip half the tests , Testing is probably the most important part of electrical work as it identifies errors and deterioration of wiring and accessories , i know it can be as boring as hell some times but its the job , where has the passion gone ,i supose im lucky and self employed so i take as long as i like and if it takes all day or all week then thats what it takes

 

[lloyd1980]

had a nightmare of fault today and couldnt have sorted it it without the IR tests

domestic house
old Wylex 3 phase disboard / obsolete (spelling?) cant get parts.
(3 phase board, single phase supply, phases linked out under main switch - its a big house)
guy wanted work in bathroom wiring more spots and a fan and a new whirlpool bath so wanted supply for the motor.
had to provide RCBO protection as bathroom on lighting and then up ring as motor supply is spurred of it via S/F spur.

Split the tails and fed new square d 2 way dis board , RCBO 10a for lighting and 32a for ring.
Ring held, lighting sadly did not so left in on the old MCB untill i could get back...................

came back 3 days leter...... the day from hell insued
removed every light/pendant /switch and spread all the conductors/ cpc's, went to each light and IR'ed each cable to find the culprit, found it after an hour or so. then had the pleasure of crawling face first through the loft fibreglass in a 2ft gap tracing the duf cable.
after countless coughing fits , itchy gritty eyeballs and a couple of hissy fits I found the cable was infact the main that came from the board and was plastered into the wall - bad times
they had 2 lighting ccts upstairs so in end I tested the other to make sure clear for an RCBO, I then tapped into it making 1 complete cct for upstairs lighting
re-introduced the rooms 1 by 1 and ok untill last room when RCBO started going bananas again. then found what can only be described as a 'nest' of JB's like ive never seen before - I spent all afternoon IR'ing all the cables and making them all off properly in new JB's this corrected the fault and the RCBO has now held and the readings are good.

So could I have got away without the IR test? .....no chance. it saved my --- and the customers window as by the end of the day I was about ready to put my head through it