Adding addition light and switch. Lamp only receiving 80v

[JohnW2]

I have a dimmer from yesteryear (around 1969 if I remember) and its SCR is fed by a bridge rectifier and can achieve full brightness. In fact never seen one that only gives 50%.

I certainly had/saw some that didn't have a bridge rectifier, and therefore the most they could manage was alternate full half cycles. I probably even built some like that (and may still have some evidence gathering dust somewhere - watch this space ).

Kind Regards, John

 

[echoes]

This 180V + 70V business smells of lamps in series to me.

 

[JohnW2]

This 180V + 70V business smells of lamps in series to me.

I agree - but it's all speculation at present.

Kind Regards, John

 

[ban-all-sheds]

I don't know about the 'new fangled' (i.e. modern) ones, but some of the simplistic dimmers of yesteryear were unable to to produce 100% brightness (which roughly equates to "average voltage 100% of supply voltage) - with the very simplest (those which used a thryristor/SCR, rather than TRIAC) had a theoretical ceiling of 50%.

OK

 

[echoes]

I agree - but it's all speculation at present.

It is indeed. I still don't have a clear idea of what's been wired to what, so I'm struggling.

I'm not buying this 180V at 100% on a modern dimmer, where the output should be pretty much a full sine-wave.

 

[JohnW2]

I certainly had/saw some that didn't have a bridge rectifier, and therefore the most they could manage was alternate full half cycles. I probably even built some like that (and may still have some evidence gathering dust somewhere - watch this space ).

So far I've only been able to find one I built which clearly does have a bridge rectifier (with 1970-sized discrete diodes). It was built around 1970/71, when I was at uni (hence the labelling of the device ), and I imagine must have been one of the first times I used flex with 'new colours'.

Kind Regards, John

 

[echoes]

I hope the settings between 2 and 5 o'clock brought much joy!

 

[JohnW2]

I hope the settings between 2 and 5 o'clock brought much joy!

That was clearly the intent, but (through all the uncertainties of long-term memory!) I'm not convinced that it every actually worked .

On reflection, unless I (and/or those I associated with) had a thing about bright illumination at the time, I presume I must have wired the potentiometer 'back to front'!

Kind Regards, John

 

[ban-all-sheds]

Been a while since I've seen top-hat diodes.

 

[JohnW2]

Been a while since I've seen top-hat diodes.

I have plenty just like that, but it's certainly been a good while since I used any of them.

However, there's obviously nothing 'obsolete' about that shape of package. These are relatively modern medium-power zerer diodes ...

Kind Regards, John

 

[stringman]

It is indeed. I still don't have a clear idea of what's been wired to what, so I'm struggling.

I'm not buying this 180V at 100% on a modern dimmer, where the output should be pretty much a full sine-wave.

http://lightwaverfcommunity.org.uk/forums/topic/lightwaverf-dimmer-for-bathroom/

if you look at post 5
I will be contacting lightwave direct to confirm this, also I will do my own little test of wiring a temporary test wire a direct live in(measured at 240v) and then a live out and I will measure that.
But I have measure the voltage of the lights in the two rooms that don't have lightwave and they have 240v tested 3 over lightwave lights and they all have 180v. All on different floors but all on the same lighting circuit.

IF you put aside the 180v issue and presume that is the "correct voltage" then the issue must be my wiring up the new light.
Now I suspect the two white cables in the pic go to another junction box or rose in another room.
But what confuses me is that generally (?) after the switch you have a blue or black as a switched live. yet on the two pics the wires are all joined like to like.

Echos I will try to replicate what I did and take photos of it. probably wont be today as its log chopping day!

Many thanks for all your help already guys, it much appreciated.

And thanks ban all sheds for resisting the temptation to laugh at lightwave again. would help to explain why my kitchen lights are so dim! though the fact I thought they were 40w when they are infact 20w running at 75% might explain it lol

 

[stringman]

Hi Chaps
sorry for the delay in replying but its been a bit hectic.
So an update on my problems.
I have confirmed that the lightwave dimmers only output 170-180v at 100% so that's solved that problem.
I was scratching my head on the additional light going dim and it running in series. I realised that I might have to track wiring back to other rooms- nightmare job!
I was about to give up when I realised that I also had to move a light in the sitting room.
Now the bathroom is a partition of the sitting room ( this is a very old house , when it was built any loo was a luxury!) so the floorboard word was in the same room as the bathroom ie the 2nd bedroom. So I decided as I was moving a ceiling light I would use that as my feed.
Followed the wiring diagram and all was well. I was a happy man until I came to change the bulb in the sitting room and discovered live mains even though the switch was off.
Previous owners had used twin and earth for the switch wire but neglected to mar the black with a red tag!

after that was resolved and re wired all was and still is good.

many thanks

 

[ban-all-sheds]

I have confirmed that the lightwave dimmers only output 170-180v at 100%

The phrase "seriously not fit for purpose" comes to mind.

Followed the wiring diagram and all was well. I was a happy man until I came to change the bulb in the sitting room and discovered live mains even though the switch was off.
Previous owners had used twin and earth for the switch wire but neglected to mar the black with a red tag!

It would make no difference if they marked the black, or of they did, what colour they marked it - the switch would do the same, and the electrons would go to the same places. If the lighting circuit loops through the lights then there will be live wires there when the switch is off.

 

[EddieM]

I was under the impression electrons went effecively nowhere in AC circuits and drift along at extemely low speeds in DC circuits.

 

[DetlefSchmitz]

I was under the impression electrons went effecively nowhere in AC circuits and drift along at extemely low speeds in DC circuits.

True, though doesn't really invalidate Bas's statement. My physics teacher at school said the speed of an electron was about a furlong a fortnight, and then went on to show the workings of a reasonable example. (I had a lot of respect for that guy.)