Light fittings only working with 20w bulbs after giving a shock

[richerich]

Got a bit weird issue that has confused a couple of electricians so thought I would try my chances with you experts

I have two light fittings both using multiple e14 bulbs
They are connected with a 2 gang switch, and a 2 gang dimmer switch

A few weeks ago a I went to replace a bulb in one of the fittings, the bulb exploded and gave me a decent shock!  Since then both fittings will only work if 20w bulbs, the 40w's we've used don't work.  If one 40w bulb is placed in a fitting with 20w bulbs that fitting will not work. When an electrician did a volt test on the fitting that originally had the issue he found there was voltage going to the fitting if no bulbs were placed in it, but as soon as a 40w was placed in the fitting no voltage was going to the fitting.

I have replaced the fitting that didn't have the original issue and it has made no difference.

The room was rewired in 2014 by the previous owner.

Any ideas on the issue guys as I am a bit stuck

 

[Evans Electric]

That exploding lamp may have killed the dimmer ,  has it been tried with a standard light switch fitted. ?  

 

[SPECIAL LOCATION]

If the information you have given is complete and you have missed nothing out...

Then so far you have not tested the bulbs or the dimmer independently of the other components..

Basic rule of fault finding..

Assume EVERYTHING is faulty until you have proved otherwise...

e.g.

Supply.

Switch.

Switched-supply to fitting.

Light fitting inc lamp holder.

Light bulbs.

Neutral back from the light fitting.

etc...

Any one (or a combination of multiple problems) could give "strange" symptoms.  

Screw thread lamps can also have issues with the sprung contact inside the fitting not making electrical contact with the light bulb itself..

Since the era of the modern energy saving lamps You also have the issue of dimmer-compatibility with the types of lamps..

And if the lamps are dimmable or not..

Sounds like your "Couple of electricians" are lacking basic fault finding skills..?  :C

Which unfortunately is all to common nowadays!

Guinness

 

[kerching]

Exactly what my learned Counsel  @SPECIAL LOCATION Said

plus

elecronic dimmers will often pass current when in the off position....might not even have been off it may just have been dimmed down

what did your couple of 'electricians' ( and I use that term in the loosest way possible) test this voltage with?

what was the voltage?

just curious

 

[kerching]

Also. Retired by previous owner?

did previous owner do it him/herself?

or did they employ an electrician?    Hopefully better than the 'couple of Electricians ' recently engaged

 

[richerich]

Many thanks for your responses. I'm not an electrician, just trying to do some self diagnosis while in isolation

@Evens Electric. It hasn't been tried with a standard light switch. There is a standard 2 gang switch that operates the lights in conjunction with the dimmer, but not been tried without the dimmer involved.

@Special Location Yeah they definitely didn't go through all of that. I have the same problem with LED and non LED bulbs. I have tested with non LED bulbs in the fittings and get the same issue. I have also tried the same bulbs in a different fitting in a separate room and they work.

@kerching. Sorry I don't know what the voltage was. I don't know whether the previous owner did it himself or hired someone. If the plumbing is anything to go by he may of cut corners!

Would a good next step to replace the dimmer switch?
 

 

[Murdoch]

FWIW I've come across cheap imported E14 bulbs that didn't work because the screw fitting was too short to contact the connections in the base of the lamp fittings!

Did you replace the fitting with another that uses E14 bulbs? If so do the 20W work and the 40W don't?

Odd to sound the least

NB: Next time you are changing bulbs please remember to turn off the switch and / or the circuit breaker

 

[richerich]

Hi Murdoch
 

The 40w bulbs that don't work in either of these two fittings do work in another fitting in a separate room, and if I put a 40w bulb in the fitting with a 20w bulb then neither of the bulbs work, so I don't think it's the issue lies with the bulbs. 

Yes the new fitting takes E14 bulbs, and yes the new fitting has the same problem where only 20W bulbs work. I should point out that the fitting that originally caused the shock is still there. It's just the other fitting that was changed.

 

 

[Murdoch]

Hi Murdoch
 

The 40w bulbs that don't work in either of these two fittings do work in another fitting in a separate room, and if I put a 40w bulb in the fitting with a 20w bulb then neither of the bulbs work, so I don't think it's the issue lies with the bulbs. 

Yes the new fitting takes E14 bulbs, and yes the new fitting has the same problem where only 20W bulbs work. I should point out that the fitting that originally caused the shock is still there. It's just the other fitting that was changed.

 

The wattage of the bulbs is irrelevant if they are 230V units

So in the fitting with issues the 2 x 20W bulbs work, but the 40W don't - so isn't the issue the 40W bulbs?

 

[poni]

have you tried 1X 40w LAMP? 

 

[richerich]

@Murdoch if the issue was the 40w bulbs I wouldn't expect those bulbs to work in any other fitting, but the do!

 

[Murdoch]

@Murdoch if the issue was the 40w bulbs I wouldn't expect those bulbs to work in any other fitting, but the do!

I refer you back to my first post on the subject:

FWIW I've come across cheap imported E14 bulbs that didn't work because the screw fitting was too short to contact the connections in the base of the lamp fittings!

 

[poni]

I was thinking that 2X40W could be too much for the dimmer that is why I asked if one 40W worked but it looks like it's the dimmer swap it out for a normal switch and see if that fixes it ,then get a new dimmer 

 

[Geoff1946]

If a lamp fails with a short, whilst powered through a dimmer, there is a VERY high probability that the triac, the active component of the dimmer, WILL be damaged. 

The dimmer would be the first thing I checked, not the last.

If its an expensive dimmer, and worth the effort, most can be easily fixed by replacing the triac.