Insulation resistance testing

[newtothis]

Sorry, I'm almost ashamed to ask this question.

Cooker switch with red indicator bulb

(1)Please tell me what exactly what I do to not get moody readings on a IR test. ?
(2) Are there any other tests that it would cause me a problem. ?

Tried to search couldn't find an answer that clicked with me

 

[Marvo]

Where are you making your IR test from? Have you got the cooker isolator switch off?

 

[newtothis]

Will be testing at an isolated, locked off CU,
mcbs off
I assumed I'd need the cooker isolator switch on but it has one of those red indicator lights.
Cooker is not yet connected.

 

[newtothis]

Marvo, I've been told the indicator light wouldn't be damaged by the 500v test voltage but could give me dodgy readings ?

 

[Richard Burns]

The indicator light will be on the load side of the switch so testing on the supply side with the switch off should test that part of the circuit OK.
If you want to test the whole circuit as one unit then linking out the switch i.e taking the conductors in to temporary wago or terminal block will allow you to do one test for the lot without the neon.
Alternatively test up to the switch and then remove the load cables from the switch and test the load side from there. record the lowest value for the circuit.

The neon indicators generally give about 512 kohms each, LED ones lower values.

 

[Leesparkykent]

Close the switch and test line to earth and neutral earth. Open the switch and test between line and neutral.

or disconnect the neon.

 

[newtothis]

Taking the conductors in to temporary wago or terminal block will allow you to do one test for the lot without the neon.

yes that's what I want to do. It's the simple mechanics of it, I have a mental block on :leaving:
Are you saying I put L,N,&E in one wago ? or each in separate.

 

[newtothis]

Or disconnect the neon sounds good- it's the how to do LOL

 

[Richard Burns]

The neon is connecting across the load side of the switch line to neutral.
If you remove the line conductor from the switch on both load and supply sides and join them together in a lever action/ push fit or terminal block so that they are connected together then this will prevent any connection to the neon and you can test the circuit.

 

[newtothis]

Thanks Lads, I can go to sleep now :icon7: have to be up at 5.00am

 

[Hawk81]

Are you saying I put L,N,&E in one wago ? or each in separate.

Think about this for a second. What readings will you get if you put the L,N+E into 1 wago?

 

[newtothis]

I'd expect the mcb to trip.

 

[Richard Burns]

I'd expect the mcb to trip.

You are testing IR with a live circuit!!!!:sad_smile:

0.00MΩ L-N, L-E, N-E

pretty picture (example values and N-E would be OK so long as the main switch was open or N removed from busbar):

 

[davesparks]

yes that's what I want to do. It's the simple mechanics of it, I have a mental block on :leaving:
Are you saying I put L,N,&E in one wago ? or each in separate.

You only need to remove one side of the neon from the circuit. So just disconnecting the live and connecting with a wago or choc block will be fine

I have a set of short jump leads I use for doing links for testing so would just use one of them if it was me

 

[newtothis]

I wasn't doing an IR test live, I'm bad, but not that bad. LOL
I'm all over this place with this post. Posted that about the MCB early in the morn.
I'd expect a dead short. Sticking them in one wago.

If I decided to wago all the conductors at the end of a live circuit. I think
there'd a short circuit that would trip the mcb and depending on the order I connected them the RCD would trip, perhaps even a muted bang. Is that more or less the case ?

The story behind why I don't know how to test accessories with neons, goes a little something like this.......


[FONT=&amp]When I was doing my buckshee 2392 course I simply avoided test rigs with cooker switches and FCUs with neons. Seemed clever at the time LOL
Since I've been with the agency I don't really get to do domestic work, except 6weeks in social housing, It was just fetching and carrying for a bloke working on light duties.

Thanks for the useful diagrams; they make it crystal clear. When I start at college again I’ll make a point of trying and getting familiar with everything. I have roughly a 3 yr plan before I'd consider myself competent.
I installed that cooker (sister in law) using the existing 10mm cable and done a pucker MWC doing more tests than you officially have to.
Did all the proper cable calcs.
[/FONT]