anybody ever...

[VoltzElectrical]

lost voltage across a 6amp rocker switch?

I was verifying a supply for an existing outside light to be replaced using a volt stick. I had previously confirmed supply to cable from kitchen switch, but no juice apparently today. I opened up the switch and tested voltage on incoming side, confirmed 240v, outgoing, only 70v!

I bypassed the switch to give permanent supply to outside light (on sensor), and switch to be replaced in due course when kitchen refurb finished but thought I would share it as I haven't lost voltage like that across such a simple device before.

Voltz.

 

[Guest55]

happens quite often with dimmers though.

 

[ipf]

Faulty/damaged/worn contacts..... come across it regularly over the years.

 

[dingledong]

As above /\/\/\ both of them

 

[VoltzElectrical]

new one on me, but good to hear your inputs. I wonder how many Electrical Trainee would be stumped by that and not know where to start looking?

 

[Octopus]

I think it's more common now due to the poor quality parts bought and installed!

 

[ipf]

Find a lot in factories...MK 20amp dp grid switches, even, working their 'locks off switching rows of fluorescents for decades.

 

[Lucien Nunes]

I'm intrigued that you find it surprising. An electrical part with contacts that have gone high-resistance. If only I could have a quid for every one of those that has come my way!

I agree light switches are generally pretty reliable but I expect this one was nearly open-circuit - you describe it as 'dropping voltage' but if it was feeding only the sensor circuit (with the lamp itself off) the load would have been very small and therefore even a high resistance switch could have shown some volts on the SL. Had it been just a tungsten lamp, I bet the 70V would have read almost zero.

 

[ian.settle1]

new one on me, but good to hear your inputs. I wonder how many Electrical Trainee would be stumped by that and not know where to start looking?

Well you've just joined them. LOL

 

[VoltzElectrical]

I'm intrigued that you find it surprising. An electrical part with contacts that have gone high-resistance. If only I could have a quid for every one of those that has come my way!

I agree light switches are generally pretty reliable but I expect this one was nearly open-circuit - you describe it as 'dropping voltage' but if it was feeding only the sensor circuit (with the lamp itself off) the load would have been very small and therefore even a high resistance switch could have shown some volts on the SL. Had it been just a tungsten lamp, I bet the 70V would have read almost zero.

Just to explain, the cable went from the switch to the outside light but I hadn't put the fitting up yet and I wanted to confirm a supply before installing it. I couldn't detect any voltage using my magic wand so opened up the switch and tested between the earthed back box and the common terminal and had 240v. With the switch closed I had only 70v on the L1 terminal. I would always expect to find 240 there between Line and Earth otherwise how would the light work?

I'm not sure I really understand your point but you're right in the fact that I shouldn't be surprised to find worn contacts, it's just that I have mostly only installed new equipment until recently.

 

[VoltzElectrical]

Well you've just joined them. LOL

Looks that way! :49: