Light circuit suddenly trips and cannot take more than 20 watts

[CK Electrical]

Hello all, just joined this site and after some help. I have not come across this before. We are currently refurbishing a house, new cables are being fitted as the work progresses and connected to existing light circuits that we have not yet got to as the refurbish continues. All electrical circuits have been fine. The particular light circuit in question has had all the new cable tested and is good. For some reason, 3 days ago the circuit tripped and the builder on site could not reset the RCBO. (All circuits are on their own RCBO's). I went yesterday and started to work through the circuit from where the builders had been working just in case they had gone through something, but all was good. To cut a long story short I removed a number of cables from an Ashley brown junction box and connected that all in Wago connectors for ease, The circuit held when the RCBO was reset, however, as soon as I turned a switch on that fed halogen lights, it tripped again and would not hold until the switch had been turned to the 'off' position. Changing lamps for LED's and again it held, but as soon as I added further LED lamps that took the current to over 20 watts, the circuit tripped again. Basically now, the circuit that quite happily allowed four 40 Watt halogen lamps to be switched on along with other LED lamps, not will not allow anything more than 20 watts. I'm completely stumped as to why this has happened. I have checked the RCBO by putting the circuit cable in to the adjacent 6 amp RCBO, but that one does exactly the same. Has anyone got previous experience of similar situation or advice on where to take it from here?

 

[Murdoch]

Visual inspection of cables?????

IR tests ??????

continuity tests????

I would say you have a damaged cable

 

[Andy™]

try doing some actual testing that doesnt involve connecting various lamps & hoping for the best and you will find the fault

 

[Tony S]

try doing some actual testing that doesnt involve connecting various lamps & hoping for the best and you will find the fault

Are you joking?

The only test would be the American bang test. No smoke, it’s good to go.

 

[Sidney]

Again test results? RCBO ramp test?

 

[ProDave]

20W of lighting = 80ma

Am I the only one thinking 1 or more light fittings is connected L-E or to the wrong neutral.

Should be pretty simple to do some dead continuity testing to see which of those it is.

 

[Sharpend]

If it holds when the switch is off but doesn’t hold when the switch is on- then your starting point is staring at you. Get some test gear out of/ off of your mode of transport and actually test again. ?????

what do they teach these days??

 

[Murdoch]

what do they teach these days??

not 100% sure its the teaching, its the ability to remember, and the need to do these things

 

[kerching]

refurb

builder

BROWN! Ashley junction box

accident waiting to happen

what are dead test results on that circuit?

who connected them?

are they the pile of Where you have to wedge a cable under too small a clamp and crush it to give low IR?

have you tried 'halving it'?

 

[CK Electrical]

Hello all, just joined this site and after some help. I have not come across this before. We are currently refurbishing a house, new cables are being fitted as the work progresses and connected to existing light circuits that we have not yet got to as the refurbish continues. All electrical circuits have been fine. The particular light circuit in question has had all the new cable tested and is good. For some reason, 3 days ago the circuit tripped and the builder on site could not reset the RCBO. (All circuits are on their own RCBO's). I went yesterday and started to work through the circuit from where the builders had been working just in case they had gone through something, but all was good. To cut a long story short I removed a number of cables from an Ashley brown junction box and connected that all in Wago connectors for ease, The circuit held when the RCBO was reset, however, as soon as I turned a switch on that fed halogen lights, it tripped again and would not hold until the switch had been turned to the 'off' position. Changing lamps for LED's and again it held, but as soon as I added further LED lamps that took the current to over 20 watts, the circuit tripped again. Basically now, the circuit that quite happily allowed four 40 Watt halogen lamps to be switched on along with other LED lamps, not will not allow anything more than 20 watts. I'm completely stumped as to why this has happened. I have checked the RCBO by putting the circuit cable in to the adjacent 6 amp RCBO, but that one does exactly the same. Has anyone got previous experience of similar situation or advice on where to take it from here?

Well I'd like to thank Murdoch for a polite and sensible response. I hadn't had chance to run a full check on cables and was just running things past people for a bit of light on the subject. So those of you who gave sarcastic and unhelpful responses - nobody likes a smart arse or a big head, so stick your heads where the sun doesn't shine. It wasn't easy to find but I went back there today and conducted systematic testing of circuits for continuity and I.S., none of which gave any alarming results. I finally came to an Ashley J501 junction box (coffin junction box) and saw that I had tightened the cable entry bands too tight on one cable, so that there were clear compression marks on the outer sheathing and also on the inner sheathing when I stripped it back. It was as simple as this that caused the tripping problem when a bigger load was added. I guess that is the problem with using impact drivers to screw the screws in, simply too tight. Something that others may wish to look out for. Now circuits are all working as they should with not problem. Thanks again Murdoch.

Well I'd like to thank Murdoch for a polite and sensible response. I hadn't had chance to run a full check on cables and was just running things past people for a bit of light on the subject. So those of you who gave sarcastic and unhelpful responses - nobody likes a smart arse or a big head, so stick your heads where the sun doesn't shine. It wasn't easy to find but I went back there today and conducted systematic testing of circuits for continuity and I.S., none of which gave any alarming results. I finally came to an Ashley J501 junction box (coffin junction box) and saw that I had tightened the cable entry bands too tight on one cable, so that there were clear compression marks on the outer sheathing and also on the inner sheathing when I stripped it back. It was as simple as this that caused the tripping problem when a bigger load was added. I guess that is the problem with using impact drivers to screw the screws in, simply too tight. Something that others may wish to look out for. Now circuits are all working as they should with not problem. Thanks again Murdoch.

 

[Murdoch]

What were the IR tests prior to finding the fault and afterwards?

 

[Evans Electric]

I was about to suggest  ..inrush of start up current on the LEDs   but its solved so all good . 

Impact drivers on connections eh!        I'm saying nothing . 

 

[Andy™]

I was about to suggest  ..inrush of start up current on the LEDs   but its solved so all good . 

Impact drivers on connections eh!        I'm saying nothing . 

some people today dont know how to use or own a screwdriver, its an impact for everything

 

[kerching]

Well somebody mentioned crushing wires under cable clamps on Aug  18th. Fair enough it was under the clamps in the lights and not the JBs ( that's why I use wago) BUT it was still  a crushing compression fault

 

[ProDave]

some people today dont know how to use or own a screwdriver, its an impact for everything

Or how to use the IR tester, which would have identified WHAT the fault was (but not obviously where)

 

[Sharpend]

some people today dont know how to use or own a screwdriver, its an impact for everything

Quite, so he’s used an impact for terminal screws and then wants to imply we are insulting his intelligence, 

I ask again - what do they teach these days? 

I rest my case your honour. 

 

[kerching]

Well regarding 'what do they teach nowadays'....according to a local provider I HAVE to do,the 3 Day 18th course because I did the 17th too early and havnt got an AMD3 ticket!

the 'course is aimed at beginners and........', so I should fit right in, they wouldn't know I was there  :slap

 

[Murdoch]

Well regarding 'what do they teach nowadays'....according to a local provider I HAVE to do,the 3 Day 18th course because I did the 17th too early and havnt got an AMD3 ticket!

the 'course is aimed at beginners and........', so I should fit right in, they wouldn't know I was there  :slap

I don't think the OP is a spark ...............

 

[Sharpend]

I don't think the OP is a spark ...............

So an imposter? Named CK Electrical ????

 

[Murdoch]

So an imposter? Named CK Electrical ????

Yup.... That's how I read it