insulation resistance

[elesde]

HI people, i got a wee problem id like to get your advice on. i have just tested my consumer unit as practice,, or rather one circuit, THE RING,

Heres some results: r1 0.58
r2 0.88
rn 0.55

Did the figure 8 and got: L1+N2 L2+N1 = 0.50.......... L1+E2 L2+E1 = 0.30 ..........N1+E2 N2+E1 = 0.30

THEN INSULATION AT 500V:
live/neut = 0.63 M
live/earth = 395 M
neut/earth = 396 M

am i right by saying all is ok apart from the low reading of 0.63 M

note.. i have hunted high and low and un-pluged and switched off all sockets, iv also switched off all switch fuse spurs and puled out the fuse's.
it should also be noted i did not do any bunch tests i used strip conectors at the consumer unit.
any help or advice would be greatly aprieciated as i wanna fit a new c/u but want the circuits sorted first.

 

[Mr Mark Sparks]

i suspect there is still a load in somewhere
the rest is ok keep looking

 

[scotsparky]

Mark what regs you loooking at 0.63Meg is a pass on Selv/Pelv systems or on 16th but Now 1Meg is requiered.

 

[Mr Mark Sparks]

school boy mistake

 

[Spudnik]

As its L&N that are low, i think you will find it could be a neon in a switched spur somewhere, or possibly a TV booster still plugged in or the like.

 

[elesde]

yea mate 1meg minimum.... still cant find a load. maybe its a damaged cable? but cant find that neither. what if i used a long length of 2.5 and replaced it with the return leg of the ring at the c/u and conected it to the first point on the circuit ,then test if reading is good then move to the next point etc until i get the low reading ,then il know were on the circuit the fault is....? its the only way i can think of to find the fault. anyone have a better idea? as im stuck!. although i know it does sound like its a load on circuit.

As its L&N that are low, i think you will find it could be a neon in a switched spur somewhere, or possibly a TV booster still plugged in or the like.

hmmm. good one . il look. also if the fused spur is switched off and fuse out would that not solve the problem of the neon.? or do i have to unwire the whole thing? il look for booster too and get back to you

no booster... gonna do the wire thing tomorow using 2.5 flex off a extention reel and goin to each point one at a time around the ring until i see the low reading and then trace the wire back from that point to the one previous to it and replace the damaged section... knowin my luck il find a load lol.... unless someone has a better idea? il keep checkin this thread for any ideas. also il let you guys know how i get on tommorow.

p.s thanks for reading and any advice and ideas already posted and in advance of any future posts.

 

[Spudnik]

Guess the furthest point on the circuit., whip a socket off the wall and disconnect it leaving two legs.

Then test each leg separately at the CU.

That should give you some idea which side you should look into further.

 

[Darkwood]

Often overlooked tends to be cooker ignition or cooker hoods as sockets/ spurs tend to be above or behind cupboard unit failing this Jason S. hit the nail on the head with guessing the mid point and splitting it down to two radials once you found the radial with low reading repeat step again to half this leg as so on....

 

[elesde]

ahh nice one fella,,cut the ring in half give me a headstart like ya say ,to which half of the ring then quater etc,rather than goin round one by one. dont know why i didnt think of it that way.Doh!. thanks again for bein on the ball. il let ya know how i do tomoz

 

[Spudnik]

Good point there Darkwood, however, he is getting these results on the RFC only.

 

[kung]

Thats also what id do always split first also seen a porch light running from a junction box under floor split ring saves time plus remember you also could have loft power running boosters etc.

 

[electricAl]

You aint got neons on any of the s/o plates i presume?

 

[elesde]

no fella , no neons on sockets only on my fuse spurs but i had switched em all of an pulled the fuses. could be a light spured off as sugested. but would mean liftin boards up ,so will split the ring test etc to pin point the fault. thanks everyone , al post bck my result

Often overlooked tends to be cooker ignition or cooker hoods as sockets/ spurs tend to be above or behind cupboard unit failing this Jason S. hit the nail on the head with guessing the mid point and splitting it down to two radials once you found the radial with low reading repeat step again to half this leg as so on....

darkwood...
FOUND IT!!

DONT I FEEL A BIT OF A ---. and in the words of homer j simpson...DOH!
im quite ashamed of myself. mind it is the first test iv ever done on a real house. only done class work before and have v little experiance. well thats my excuse

Firstly id like to thank everyone who replyd to my post. youv all been top notch and have given me examples which i will pobebly run into in the future and will now know of.

i did the split ring into radial idea etc only to find the load in a very acsessable place!

IT was the cooker!
gas fueled and was for the sparker after all,pluged into a socket behind the unit...
i did originaly dismissed this idea as my old cooker i had left in my old house was gas but the sparker was ran from a battery. another lesson learnt!

 

[scotsparky]

store it !!!! it will make you loomgood in the futre and save you a load of time later as well.

 

[Darkwood]

No worries Elesde the best way to learn is to trip over your own shoe-laces, i probably missed the same thing years ago hence it popped into my head.