r1+r2 test on 2 way lighting

[Davem]

Evening gents bit of advice, testing the above and when switches are on a reading of 3.13 ohms is apparent. Now when a switch is turned off I would expect a dead circuit I.e infinite >2000 but no a reading of 60.4 ohms is shown any thoughts on what this could be ?? Cheers

 

[R G]

I suspect the 60 ohms is from the strapper thats not on as it were , the reading your getting is through the lamp ,

 

[Davem]

Sorry I don't understand as it were ??? Also the lamp I was testing was taken out ?

 

[R G]

What about the other lamps on that circuit , because the feed to that 2 way circuit is common to the other lamps as well

 

[Octopus]

3.13 looks a bit high - how far apart were the switches?

 

[Davem]

No not all other lamps were removed, so this could point to that but why would it show that is it reading all lamps on that circuit but why isn't it picking up on any other part of the circuit standard 1 way light either on or off. Is it due to the strappers cheers

 

[trev]

I'd also say it's high, is this in a domestic environment or a commercial?

 

[Octopus]

No not all other lamps were removed, so this could point to that but why would it show that is it reading all lamps on that circuit but why isn't it picking up on any other part of the circuit standard 1 way light either on or off. Is it due to the strappers cheers

IMHO - no. both your reading are too high

 

[Davem]

That's what I thought it is in done in 1 mm t+e and it's domestic

 

[trev]

Dave, if you're not doing the test proerly then you're A going to get daft readings and B wasting your time.
Go back and do it properly mate then if you're still getting silly readings then yell

 

[R G]

The thing to be done on all lighting circuits is to remove all lamps and equipment like drivers , transformers , fans , shaver points etc to carry out the continuity and I/R testing , otherwise the readings are not going to be correct , because of the high readings your getting I would use the wandering lead method for R2 only and track down any loose connections that way as well ,,,

 

[Octopus]

That's what I thought it is in done in 1 mm t+e and it's domestic

If you know the cable sizes and the layout of the house, you can have a good go at estimating the length and thus the expected reading..........

 

[Davem]

Dave, if you're not doing the test proerly then you're A going to get daft readings and B wasting your time.
Go back and do it properly mate then if you're still getting silly readings then yell

Done it all twice and checked terminations 2 way light is end of circuit a junction before there is a reading of 0.84 but at the final light ( 3 spot lights on landing ) a reading of the above is shown I have tracked cables all IR tests fine just confused as to what it could be ?

 

[trev]

Time for a daft question, is the circuit disconnected at the CU?
With the sudden jump in the readings I'd be thinking about a JB somewhere with dodgy connections. As Murdoch says, you should be able to have an educated guess at what the reading should be, give or take.

 

[Davem]

Connected in a connector block at ccu. Only 2 junction boxes on circuit both inspected and all terminations sound . This is a weird one all other r1 r2 test on this circuit gradually increased until the end of the circuit 2 way light

 

[Octopus]

connected in a connector block at ccu. Only 2 junction boxes on circuit both inspected and all terminations sound . this is a weird one all other r1 r2 test on this circuit gradually increased until the end of the circuit 2 way light

wtf???

 

[Davem]

wtf???

??? ????

 

[R G]

I would trace that cable from that fitting back to the last point , disconnect all the equipment etc as I already said and use a wandering lead method , and follow the circuit through , this way would be more accurate than R1 R2 method in that the fault could also be on the Live supply through possibly a faulty light switch if a junction box method is used ,

You could also apply this same wandering lead method on the Live as well if the fault lies there if required,,,

 

[Davem]

I would trace that cable from that fitting back to the last point , disconnect all the equipment etc as I already said and use a wandering lead method , and follow the circuit through , this way would be more accurate than R1 R2 method in that the fault could also be on the Live supply through possibly a faulty light switch if a junction box method is used ,

Faulty light switch could possibly be the one I will know more tomorrow when I go back. Will do as you say and hopefully find the fault!! Cheers

 

[R G]

Faulty light switch could possibly be the one I will know more tomorrow when I go back. Will do as you say and hopefully find the fault!! Cheers

As I said earlier the 60 ohms is lamps still in , but the other reading is the one to be found and rectified ,,,

 

[Octopus]

Are you using Kewtech adapters? They can give off unusual readings.....

 

[Davem]

All fluke pretty new kit too. It certainly is a head scratcher. Will definitely post what I find tomorrow thanks for help and advice guys

 

[GLENNSPARK]

Are you using Kewtech adapters? They can give off unusual readings.....

they shouldn`t do...as long as they are kept clean, are interfacing correctly with the fitting and the multi-lam sockets are also clean...

 

[tazz]

If you work this out.....the average 100w lamp is aprox 550 ohms, so unless there are over 10 still on the lighting circuit, the must be no lamps still in with 60 ohms, and a faulty switch or junction box, I would suggest at least a few hundred ohms when carbonised..this level would suggest a lighting or shaver transformer still in the circuit or bathroom fan

 

[R G]

There could be anything on this circuit , If as the Op says he has these readings and he has access to joint boxes , it shouldn't take much sorting with a wandering lead , see how he gets on with it and what he finds

 

[tazz]

Going to correct myself after talking to Glenn.....before someone see my mistake that a load can`t be measured on a R1/R2 test....so my theory, of a transformer or fan is out the window...

 

[R G]

As I said there could be anything on that circuit and we don't fully know how he has been testing it and wether he had fully isolated the circuits at the D/B , just have to see what he comes back with ….

 

[telectrix]

If you work this out.....the average 100w lamp is aprox 550 ohms, so unless there are over 10 still on the lighting circuit, the must be no lamps still in with 60 ohms, and a faulty switch or junction box, I would suggest at least a few hundred ohms when carbonised..this level would suggest a lighting or shaver transformer still in the circuit or bathroom fan

tazz.that 550 is when hot.cold resistance is much less, usually round 50-70.

 

[telectrix]

i'd be getting the wander lead out. first R2 and then R1. with the latter, test on both sides of switch as well. see if there's a significant difference across the switch.