Problem of the week - ceiling rose

[steptoe]

close adam,

all reds together then test to each black in turn, when continuity found turn switch off and continuity lost, I always do this 3 times.!

what about the other 3 reds & blacks though?

 

[springcrocus]

Yes, Adam, you're in the right area and your method would work. But think about the whole scenario. I am not kidding when I say that ten minutes after going in the front door, I am leaving. And if the tea was colder, it might be sooner.

Running a load of continuity tests might take longer than you think, and if the next light in the loop was swiched on and had a 100W lamp in it, another pair of wires would read about 500 ohms. Easily distinguished from a reading of a fraction of an ohm but might still throw you depending on what you are measuring with.

I could do the whole job with a small screwdriver and a simple electricians measuring instrument (note my careful choice of words), but I would take my multifunction tester so I could do a quick Zs at the end.

So now walk yourself through the steps, from going in the front door to leaving again and see if you can find a quicker way.

 

[steptoe]

I could do the whole job with a small screwdriver and a simple elctricians measuring instrument (note my careful choice of words),

are we allowed to promote this to apprentices/learners though?

Deke will send the H&S polis round to yours in the middle of the night you know!!!!!

---------- Post Auto-Merged at 18:50 ---------- Previous post was made at 18:49 ----------

but I would take my multimeter so I could do a quick Zs at the end.

Im not so sure about that......

 

[springcrocus]

And I thought you were trying to unload all those cheap neons, Steps. Opportunity knocks!

 

[steptoe]

@

 

[springcrocus]

Steps, PM heading your way.

 

[steptoe]

sorry for delay.

 

[adam1984]

I am a slittle stumped so i will await you answer / outcome (it will probably all click when told!!)

 

[springcrocus]

Im not so sure about that......

:Blushing Sorry, Steps, I only just noticed what you meant. Post now corrected, and thanks. :Blushing

 

[springcrocus]

Nobody else want to have a go at this? If no further responses, I will post up my solution tonight.

 

[markyboy2782]

Ok here goes,

Power off at CU

All blacks together, all reds together

Meter on continuity

Flick the switch on to add a short on the line

Go back to the ceiling rose and remove 1 black at a time

Once the fault clears that is your switch live, sleeve as required all other reds/blacks fixed into the rose as required.

Power back on

Quick ZS as you mentioned

Done!!!!!

I hope....

Expanded on Adams idea so if i'm right cheers Adam, if not i'm as stumped as he is.

 

[sparkytim]

Only problem is lamps in circuit from fittings before and after this one will show as low resistence.

 

[springcrocus]

OK, guys, this is how I would do it.

Turn off the CU with the main switch AND turn off the breaker for the relevant circuit, or turn them all off if you like. The circuit will probably be turned off anyway because the customer was trying to change the fitting and messed it up.

Go to the room with the new ceiling rose, shout to customer "two sugars, please", and using your voltage tester, make sure all wires are dead.

You will know that you are really only trying to identify the switched live which is one of the black wires. Therefore, the other three black wires are neutrals and the reds are lives, lines, phases or whatever you want to call them.

Therefore, immediately terminate the four red wires into the centre section of the rose. Then carefully spread the four black wires apart and make sure the ends don't touch anything else (they will already be dressed, remember). If you are confident that you can do this successfully, please continue. Otherwise, I would recommend that less experienced operatives terminate the four black wires into a chocblock or similar for extra safety.

No go back to the CU and turn on the main switch and the lighting MCB. Back to the room and turn on the light switch.

Now back to the rose and CAREFULLY measure for a voltage from the earth terminal to each of the black wires. If only one shows a reading, this is your switched live. If more than one, then there is another light turned on somewhere and you will need to turn the lightswitch in your room off again to see which of the wires went dead. If you trip the RCD, then toss your

 

[Manator]

Remember to carry out each stage carefully guys and follow the advise given above when testing any live circuit, if done properly it can be done safely.

 

[Bacon]

I had the same scenario a few years with my son's friends dad changing a fitting in the bathroom.

My lad came down for some 5A fuse wire gave it to no probs,

Comes back down for some more then i ask what he's friends dad doing he say oh changing a light in bathroom,

So i look at how much 5A fuse wire i have left and tell me lad tell him i'll be up in 5 minutes as i've not got much wire left,

Took all of 10 minutes to sort out.

 

[Manator]

The testing method described is one used all the time by fully experienced electricians and is faster than the prescribed method, and is a method that I would adopt if faced with a similar fault. However for balance and not to pass on any "bad habits" I will now detail how it should be done if asked during any exam or college discussion.

1. Disconnect the supply to the circuit and follow the safe isolation procedure, when satisfied that the circuit is now dead.

2. Separate all cables so that no two cables are in contact with another.

3. Using a wander lead test for continuity from the supply to the ceiling rose, and mark that cable.

4. Using a wander lead test for continuity from the switch to the ceiling rose and mark this cable.

Using the described testing above we have now found our supply feed, and our switch wire.

Sleeve/ mark these cables and connect into the ceiling rose using the correct terminals provided.

If there are any more cables these can be checked for continuity to other lighting outlets that will prove polarity and use. If continuity is verified these can also now be connected into the ceiling rose using the correct terminals provided.

Before the power is supplied R1+R2 tests can be performed and insulation tests to verify all connections are correct.

When satisfied energise the circuit and carry out any live tests to satisfy the requirements.

Fill out your minor works certificate and include all the test results required, give a copy to the client and send in your invoice.

 

[springcrocus]

The testing method described is one used all the time by fully experienced electricians and is faster than the prescribed method, and is a method that I would adopt if faced with a similar fault. However for balance and not to pass on any "bad habits" I will now detail how it should be done if asked during any exam or college discussion.1. Disconnect the supply to the circuit and follow the safe isolation procedure, when satisfied that the circuit is now dead.

2. Separate all cables so that no two cables are in contact with another.

3. Using a wander lead test for continuity from the supply to the ceiling rose, and mark that cable.

4. Using a wander lead test for continuity from the switch to the ceiling rose and mark this cable.

Using the described testing above we have now found our supply feed, and our switch wire.

Sleeve/ mark these cables and connect into the ceiling rose using the correct terminals provided.

If there are any more cables these can be checked for continuity to other lighting outlets that will prove polarity and use. If continuity is verified these can also now be connected into the ceiling rose using the correct terminals provided.

Before the power is supplied R1+R2 tests can be performed and insulation tests to verify all connections are correct.

When satisfied energise the circuit and carry out any live tests to satisfy the requirements.

Fill out your minor works certificate and include all the test results required, give a copy to the client and send in your invoice.

Just trying to give our up-and-coming young sparks a head start in the competitve world of tendering for work.

 

[philbas]

and you can do this all in 10 mins ??

 

[springcrocus]

and you can do this all in 10 mins ??

Who is this aimed at? I can do my bit in the time, and have done on numerous occasions.

 

[Bacon]

and you can do this all in 10 mins ??

I knew what the problem was before i got there by the request for more 5A fuse wire

I think it was aimed at me not you Springcrocus.

As Springcrocus said it took him longer to type out the answer to the question than do the job so i'd say 10 mins is what time it prob took Springcrocus to do it.