Wiring lights in series

[sparkwright]

In a church wired in about 1960, the chandaliers with ordinary lamps were wired deliberately in a strange way.

A bank of switches were wired in such a way so the lights were in parallel OR series.

The whole point of this meant one way the lights could be ordinary brightness, the other way meant they would be dim.

In other words, a primitive dimmer switch - probably before dimmer switches were even available.

It was clear this set up was deliberate as a means of dimming, as one switch was marked 'pilot lights'.

This set up was genius in it's simplicity.

But is it acceptable?

 

[JohnW2]

In a church wired in about 1960, the chandaliers with ordinary lamps were wired deliberately in a strange way. ... A bank of switches were wired in such a way so the lights were in parallel OR series. ... The whole point of this meant one way the lights could be ordinary brightness, the other way meant they would be dim. ... In other words, a primitive dimmer switch - probably before dimmer switches were even available.

Indeed. I've done the same myself in my time, and you still occasionally see it mentioned here. If one only wants two levels of lighting, it's great - and, unlike dimmers, does not 'wear out' or die when a lamp blows! It's obviously intended for incandescent lamps, and may well not work (as intended, or at all) with 'new-fangled' light sources!

It was clear this set up was deliberate as a means of dimming, as one switch was marked 'pilot lights'. This set up was genius in it's simplicity. But is it acceptable?

I see no reason why not, do you? It obviously has the capacity to seriously confuse electricians, so it would be kind to document it well (including a clear 'explanation', in case it is an 'electrician' who comes across it ).

Kind Regards, John

 

[EFLImpudence]

Interesting.

I have not come across this nor remember it on here.
How many switches and lights are involved?

 

[JohnW2]

Interesting. I have not come across this nor remember it on here. How many switches and lights are involved?

Yes, it's interesting. I think you'll find that bernard, for one, sometimes mentions it here. As I said, I think the main problem could be the progressive disappearance of the incandescent era.

Kind Regards, John

 

[OwainDIYer]

The names "Marvel" and "Lundberg" come to mind for various configurations of tumbler switch for series/parallel wiring, and arranging odd or even numbers of lamps for multiple light levels - sometimes with two-way and intermediate switching as well!

 

[JohnW2]

How many switches and lights are involved?

There are umpteen ways of doing it, whiuch can get quite complex, but I think one would probably be hard-pressed to do it easily with standard 'electrical accessory' switches. This is one basic way, but it requires a 2p2w break-before-make switch (which I don't think you'll find as a standard 'accessory').....

each of those lamps could, of course, be sereral in parallel.

Kind Regards, John

 

[sparkwright]

Interesting.

I have not come across this nor remember it on here.
How many switches and lights are involved?

Can't remember. Years ago, and didn't get a proper look. Don't think any special accessories were used as such, though John's diagram has made me think again.

Just suddenly remembered it today, and thought how clever it was - providing it was done in a safe way.

 

[JohnW2]

Don't think any special accessories were used as such, though John's diagram has made me think again.

The problem with any 'simple arrangement (and maybe all arrangements) is that there is probably always going to be some point in the circuit which has to be switched between L & N to achieve the series/parallel change-over. To do that with two separate manual switches would obviously result in a big bang if one got the switch positions wrong which is why a '2-pole' switch (i.e. essentially two mechanically linked switches) is usually required, as in the example I posted.

Of course, this is only the start of something that can get extremely complicated. For example, if you have four lamps, you can have all four in series, all four in parallel, or two pairs of 'two-in-series' in parallel, giving three lighting levels - and an increasing nightmare of switching logic! You can even have 'asymmetrical' options, if you want different lamps at different brightnesses as one of the options (e.g. two in series in parallel with one single lamp!

Kind Regards, John

 

[EFLImpudence]

But wouldn't they have to be wired in pairs or pairs of groups?

I was thinking at first reading that all the lights were in series.

 

[JohnW2]

But wouldn't they [would] have to be wired in pairs or pairs of groups?

Not necessarily. With sufficiently complex switching, you could have, say, 5 lamps which could all be in series, or all in parallel (but see below).

I was thinking at first reading that all the lights were in series.

One can't have very many in series if one wants to get significant light output! IIRC, for an incandescent lamp, light output is roughly proportion to voltage to the power 3.4. That means that halving the voltage (2 in series) will reduce light output to about 9.5% of a single lamp, reducing voltage to a third (3 in series) will reduce light output to about 2.4% and reducing voltage to a quarter (4 in series) will reduce light output to less that 1%. Hence, in practice, two lamps (or groups of lamps in parallel) in series is probably about the useful limit, if one actually wants useful amounts of light.

Kind Regards, John

 

[ban-all-sheds]

IIRC, for an incandescent lamp, light output is roughly proportion to voltage to the power 3.4.

Came across this many moons ago:

 

[JohnW2]

IIRC, for an incandescent lamp, light output is roughly proportion to voltage to the power 3.4.

Came across this many moons ago:

Fair enough - that's an exponent of around 2.4, rather the 3.4 I suggested, so perhaps that's a consequence of my very fallible memory. Whatever, that graph only gives light outputs at 25% and 50% voltage of about double what I suggested (i.e. around 3% and 19.5% respectively) - so I think that my bottom line suggestion probably remains correct - that 2 lamps in series (across a source of the nominal voltage of one of them) is about as far as one can go if one wants significant light output.

Kind Regards, John

 

[big-all]

ok i fully understand the series and parallel implications power wise
how does it stand regulation wise going from live to switched live backed on to switched live and live again all be it at 115 volts
just a thought is it "normal" and covered by the regs ??
just a thought ?

 

[JohnW2]

ok i fully understand the series and parallel implications power wise ... how does it stand regulation wise going from live to switched live backed on to switched live and live again all be it at 115 volts just a thought is it "normal" and covered by the regs ?? ... just a thought ?

As I said at the very start, I don't personally see any reason why it should be non-compliant with regulations. It obviously is not 'usual', 'common' or 'normal' but that, in itself, does not make it non-compliant. To be non-compliant one would have to be able to think of some regulation which it was non-compliant with, and I personally can't - can you?

Kind Regards, John

 

[big-all]

more off a "sh1t whats all this about" moment lol
the regs cover every avenue in a normal domestic situation assuming only the normal is applied
in other words it wont cover any unusual senario like this as its off on a tangent like you cant cover every possible senario within the regs iff you go off on a tangent to an area not specifically covered
doesn't mean its complies just mean the senario is outside the scope off the regs