Lighting Circuit r1+r2 values.

[CDB]

Hi,

I was doing my r1+r2 tests on a lighting circuit yesterday in a 6 bed house over 3 floors. Approximately 20 points not including switches. Mainly pendants but some light bars etc and almost all LED or low energy halogen type bulbs. Closed circuit r1+r2 values range from 0.88 on ground floor to 3.06 on top floor.

The lights all work ok. I believe I have found one pendant with a discontinuous earth not picked up on a recent EICR done by a 3rd party, which I will return to this week and fix.

However, a couple of pendants were giving me values of over 130 ohms when the switch was open (light off), which I check as part of the polarity test.

Can someone help me understand why these high r1+r2 values might be occurring?

Thanks

Chris

 

[Ian1981]

Have you carried out an insulation resistance test on the circuit?

 

[CDB]

Ah yes, good question. I should have said.

I have performed a R1+Rn - R2 insulation test and got 130Mohm. Not perfect but acceptable. R1 - R2 has not been done as yet because I don't want to have to remove all the bulbs!

 

[DPG]

Are you confusing readings somewhere? You mention a continuity reading of 130R and an IR reading of 130M. Is it just coincidence you have similar results? (I know they're a factor of a thousand different, bu tyou know what I mean).

 

[Risteard]

You're reading through the lamps back to the neutral bar.

 

[CDB]

Are you confusing readings somewhere? You mention a continuity reading of 130R and an IR reading of 130M. Is it just coincidence you have similar results? (I know they're a factor of a thousand different, bu tyou know what I mean).

No its just a coincidence. I've got two pendants its happening on. one is reading around the 130 mark and the other is at 150.

 

[CDB]

You're reading through the lamps back to the neutral bar.

Can you explain what you mean. Sorry.

 

[westward10]

Turn the switches on, why have you got them off. You have lost the R1 return at the light with the switch off.

 

[CDB]

Turn the switches on, why have you got them off. You have lost the R1 return at the light with the switch off.

You misunderstand. This is for just one of the two problem pendants. With the switch closed/on I'm getting 2.89ohm but with the switch open I'm getting 150ohm when I would expect to see >2000ohm (open circuit) as I do for all of the other pendants.

 

[westward10]

Do you have all the lamps removed.

 

[CDB]

Do you have all the lamps removed.

Nope but I'm using the same method on another 18 pendants on the same circuit and getting open circuit when The switch is open/off. And many of them have the same model of bulb so why would these two be different?

 

[Pete999]

Hi,

I was doing my r1+r2 tests on a lighting circuit yesterday in a 6 bed house over 3 floors. Approximately 20 points not including switches. Mainly pendants but some light bars etc and almost all LED or low energy halogen type bulbs. Closed circuit r1+r2 values range from 0.88 on ground floor to 3.06 on top floor.

The lights all work ok. I believe I have found one pendant with a discontinuous earth not picked up on a recent EICR done by a 3rd party, which I will return to this week and fix.

However, a couple of pendants were giving me values of over 130 ohms when the switch was open (light off), which I check as part of the polarity test.

Can someone help me understand why these high r1+r2 values might be occurring?

Thanks

Chris

View attachment 37379

Do you mean R1+R2? r1 r2 and rn are for ring finals only

 

[Des 56]

Its hard to follow your description of what is your situation but here 's a try

The only thing you are removing when you switch off are the switch live back to the pendant and the switch contacts
If you are now getting 130 ohms where 1000s were expected,it seems to me it can only be via the open switch
Have you measured the switch itself as a separate item

 

[static zap]

Comparing cold bulb and 130R ,just leaves heat damage ,
causing tracking somewhere ,or another cause.
Are the halogens 230V ,or is some 12V converter envolved .

 

[Wilko]

Any 2 way lights in the mix?

 

[westward10]

Are you doing an EICR or fault finding.

 

[CDB]

Thanks for all the help guys.

An EICR was done but NOT by me. This issue was not raised and neither was the discontinuous earth. The remedials listed were fixed and I have since changed the CU and am testing all the circuits I've moved for my EIC.

There is two way on the hallway lights but not the ones affected. Screenshot below shows my readings.

Thanks again.

 

[westward10]

Are you registering voltage between line/earth at the light fitting and is the insulation resistance clear.

 

[westward10]

Is this 130 and 150 ohms or meg ohms.

 

[CDB]

Is this 130 and 150 ohms or meg ohms.

ohms for the switch on / closed for those particular circuits. 130Meg Ohm for the r1rn to r2 insulation resistance.