Help checking lighting circuit

[raustin]

Hi Guys

When checking a lighting circuit you obviously need to check at each point on the circuit, switch and light fitting.

What do you do when you can't get to the cable in the light fitting??

For example, in my kitchen I have 3 spot lights on a bar. I'm not able to remove the bar without damaging the ceiling, so this isn't an option. I can check the continuity of L1 and LN in the fitting, but can't check L2.

Any advice on what you do when this happens.

Rich

 

[telectrix]

do you mean R1,Rn,R2 ??? if its a metal fitting, you can clip on to any metal part, use a lightmate suitable for whatever lamp fitting it is.

 

[Farmelectrics]

do the r2 method wandering test lead and calculate the live test its what the niceic advise on there dvd

 

[IQ Electrical]

do the r2 method wandering test lead and calculate the live test its what the niceic advise on there dvd

Calculate Zs from an R2 reading?

Must be missing from my complete set of NICEIC dvd's!

 

[Farmelectrics]

zs = ze + R1 + R2 THEREFORE IF YOU HAVE THE ZE VALUE AND R2 VALUE YOU CAN CALCULATE YOUR ZS IS THAT NOT CORRECT

 

[IQ Electrical]

zs = ze + R1 + R2 THEREFORE IF YOU HAVE THE ZE VALUE AND R2 VALUE YOU CAN CALCULATE YOUR ZS IS THAT NOT CORRECT

Well no, where is R1 ?

 

[Farmelectrics]

This is shown on niceic perodic testing and inspection dvd or am i reading it wrong iq electrical interested to here your views

 

[Farmelectrics]

You can use test method 1 or test method 2 tony cable uses test method 2 on the niceic dvd watching it as we talk

 

[IQ Electrical]

This is shown on niceic perodic testing and inspection dvd or am i reading it wrong iq electrical interested to here your views

I think you might have misheard, you can't calculate Zs purely on an R2 reading with Ze, you need R1.

You can calculate R1 from R2 once you know the ratio of cross sectional area difference between line and cpc conductors but it's not really a prescribed method.

 

[telectrix]

yes, but you need R1 and R2 to add to Ze to calculate Zs. in the time taken to discuss this, you could have done the test, filled out the certificate, laid the ( female ) customer, had a cup of tea and still got home in time for Top Gear repeat on Dave.

 

[IQ Electrical]

yes, but you need R1 and R2 to add to Ze to calculate Zs. in the time taken to discuss this, you could have done the test, filled out the certificate, laid the ( female ) customer, had a cup of tea and still got home in time for Top Gear repeat on Dave.

I'm doing these inspections all wrong......

 

[chiplard]

do you mean R1,Rn,R2 ??? if its a metal fitting, you can clip on to any metal part, use a lightmate suitable for whatever lamp fitting it is.

You do need to careful doing this tho mate as there is nearly always some resistance between the metal fitting and the earth. ie plating, poor connections etc

It could cause unnecessary tail chasing of a high R1+R2 reading.

I always try and get to the earth terminal where possible.

 

[SirKit Breaker]

get a set of lightmates, fit the correct one into the lamp holder, shove the red lead in and poke the earth lead onto the metal fitting. When doing Zs shove the blue lead in as well and push your button, job done, and no more taking light fittings down. It was the best £50 i ever spent.

Cheers.........Howard

 

[Farmelectrics]

thats correct so you can find the zs from this calculation are company has been using this method for there perodics

 

[Farmelectrics]

iQ electrical i understand were your coming from there are easy methods im just talking about a particular job we were doing on raft lighting in a office area that was the method we used the conuctors were the same cross sectional area ie 1.5mm so if the r2 was 1 ohm r1 would be 0.50 ohms so we then calulated the zs on are engineers instructions long winded i know but there you go

 

[IQ Electrical]

iQ electrical i understand were your coming from there are easy methods im just talking about a particular job we were doing on raft lighting in a office area that was the method we used the conuctors were the same cross sectional area ie 1.5mm so if the r2 was 1 ohm r1 would be 0.50 ohms so we then calulated the zs on are engineers instructions long winded i know but there you go

I think I'm losing the will to live, if the conductors were the same csa, why would you have different values?

You should ask your 'engineer' to show you where this procedure is documented in Guidance Note 3.

I'm not 'having a go' at you but it's important to show the correct procedures on the forum as many use these threads for answers and as study aids for 2391-10 etc.

 

[nickblake]

Get you self a light mate kit like howard has said dont half save time and stress so easy and the megga set come with a sexy crock clip lead set , Paul thats one hell of a complex way of testing and as Iq has said correct procedures should be followed ,

i belive you cant get the fitting off the ceiling , gently run a knife round the paint , or gently tap the fitting then it may well come away with out damage ,

 

[andekoch]

Seem to remember reading somewhere (in a guidance note) that if the light fitting/ cable is not easily accessible you can check r1 + r2 at the switch and note it on the cert.

 

[malcolmsanford]

I know i'm getting old, and my lass tells me that as I get older I'm getting worse, but you read on here guys wanting to do the 2391-10 and worry about this and worry about that, the scenario is stressful and what RCD protection for what purpose and this thread is well confusing. I thought we were talknig about a lighting circuit, but it seems there must be a ring final circuit also involved as we are doing r1 + r2, and I ignored the rn.

It is and always has been, and I think always will be Zs = Ze + (R1 + R2), never as it be Zs = Ze + (r1 + r2). It may be a poiint of just being a crotchity old git, but C&G love marking you down on this and the eternal ring main, which is a ring final circuit.

If we get use to using the correct terminology on here, it will help all those doing the 2391-10 and also help to answer questions.

Rant over

 

[rmc86uk]

For lighting circuits Zs like above can always be calculated Ze + R1 + R2. If you do an actual Zs test on a lighting circuit its value is usually the same or there abouts results as your calculation. It takes a couple of minutes to get your calculator out and go through all the Zs on the test sheet providing you have the Ze and R1 + R2 readings. Always do a Zs test on sockets though and not a calculation as this is the most dangerous part of a circuit as it enables the consumer to plug an appliance in with their hand.

Sent from my HTC Desire using Tapatalk