Discuss ins res 40 meg in the Electrical Forum area at ElectriciansForums.net

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:   American Electrical Advice Forum

Reaction score
120
doing dead testing today on a new installation 18 circs all>299 apart from outside lights i got 40 meg l-n and 100meg l-e & n-e went through the motions and found it to be a lamp holder in a tungston bulkhead removed lamp holder and disconnected it tested across lamp holder and it was giving these readings
(just a lamp holder on its own!!) anyone had anything similar
 
Last edited:
May have been a PIR sensor on the circuit anywhere or switched spur with a neon.

These are normally the culprits and can easily be missed, however your 40 reading is within the limits so no major cause for concern.:)
 
let me clarify this is odd it was the actual lamp holder on its own disconnected, sitting on the site agents desk ceramic es type damp maybe, im going to check it again tomorrow i was just being fussy it niggled me
 
can you please giv me ya apinon on this i tested insulation resistence 500v dc on a light circuit 2day after i changed a c/u i knw i shud of checked it b4 hand lol the reading was 295M ohms the range went half way across the scale on the megger tester i think this may be a low reading may require futher investigation, wot do ya reken fellas???
 
can you please giv me ya apinon on this i tested insulation resistence 500v dc on a light circuit 2day after i changed a c/u i knw i shud of checked it b4 hand lol the reading was 295M ohms the range went half way across the scale on the megger tester i think this may be a low reading may require futher investigation, wot do ya reken fellas???
295 Mohms that a clear reading
 
i got the megger 1502/2 my concern is normaly wen testin at 500v dc Mohm scale the reading normaly goes all the way across the scale but this time it stopped half way across the scale hence readin 2.95MOHM it was as if a lamp was left it pendent or somethin, all the lamps where removed prior to testin?
 
Interesting readings there as my Robin goes up to 1000.

however, 295 is perfectly fine, however, on CU change or PIR you should really start off on 250V just to make sure everything is clear and then proceed to 500V.

Otherwise, you may fry a fitting somewhere!
 
i think im just use to new installs expectin the scale to go all the way to 2.99Mohms lol
thanks for ya help fellas i shud be able to re energize the circuit 2moz just wanted to mk sure 100% before hand hand ;-)

the scale says 2.99M ohms on healthy circuit on my megger tester 1502/2 in this case however it reads 2.95M ohms

the scale says 2.99M ohms on healthy circuit on my megger tester 1502/2 in this case however it reads 2.95M ohms

sorry fellas me metre reads 99.9 for an ealthy circuit testin at 250v dc i i couldnt find the fault checked all the fitting the cable runs f****** everywhere noi where to be seen so my verdict wos the condition of the cable has had it, recemended the upstairs light circuit need rewire :-/
 
Last edited by a moderator:
Sorry mate but I really am lost here.
You really should get your readings correct beacause its confusing the hell out of me.
The maximum reading for insulation resistance on a megger mft at 500v dc is 299MOhms and reads as >299.

Please check your readings carefuly, someones life could be at stake here.

Regards.
 
i knw wot im doin pal on a healthy circuit the reading goes full scale and reads 500v dc Mohms scale and reads 29.9Mohms the reading i was gettin was 3.71Mohms the and only went half way across the scale suggests i defect somewhere hence futher investigation needed ;-)
 
i knw wot im doin pal on a healthy circuit the reading goes full scale and reads 500v dc Mohms scale and reads 29.9Mohms the reading i was gettin was 3.71Mohms the and only went half way across the scale suggests i defect somewhere hence futher investigation needed ;-)

Nobody said you didnt know what you were doing.

We are simply trying to establish why you are getting 29.9Mohms on your meter "full scale".

Personally, i think you MAY have your meter set on the wrong scale.

Remember, YOU asked for OUR help. Which is what we are doing.
 
i jst checked me metre when i test on 500v dc the scale goes to 299M ohm when i test at 250v dc the scale goes to 99.9 Mohm i hope this has cleared up the confuison soz about tht ;-)

the problem i had the other day was on a lighting circuit upstairs when testing at 500 v dc the reading read 2.95mohms and only went halfway across the scale normaly when i get this reading it may suggest a lamps been left in somewhere but i removed everyin prior to testin i checked all the fittings lites switches and all the cable runs couldnt find a fault anywhere so i decided the cable was just old and needed rewire wot do ya recken?
 
i think your rcd isn't going to hold, if you've changed the board to the 17th ;)
 
how do ya mean i tested the rcd 15Ma both cycles no trip 150Ma both cycles tripped 5.6ms 8.7ms respectivaly thn 5x rated current both cycles 5.4 ms - 8.7 ms respectivaly ;-)
 
150Ma both cycles tripped 5.6ms 8.7ms respectivaly thn 5x rated current both cycles 5.4 ms - 8.7 ms respectivaly ;-)

Hi

For a 30mA RCD a 150mA test and a 5x test are one and the same thing. it should be half x, 1 x, and 5 x. 15mA, 30mA and 150mA.

Cheers
 

Reply to ins res 40 meg in the Electrical Forum area at ElectriciansForums.net

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

Electrical Forum

Welcome to the Electrical Forum at ElectriciansForums.net. The friendliest electrical forum online. General electrical questions and answers can be found in the electrical forum.
This website was designed, optimised and is hosted by Untold Media. Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock