Light circuit suddenly trips and cannot take more than 20 watts

Talk Electrician Forum

Help Support Talk Electrician Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

CK Electrical

Member
Joined
Oct 11, 2015
Messages
7
Reaction score
0
Location
Essex
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?

 
Again test results? RCBO ramp test?

 
Last edited by a moderator:
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.

 
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??

 
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.

 
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 ...............

 
Top