Christmas tree lights

[David E]

Ok I know this is now a proper electrics question, but the reasoning for them not working is bugging me.

160 24v 0.25A outdoor multifunction lights ie 4 circuits in series each of 40 bulbs

Circuit A, B & C are fine, D works for the first 30 bulbs but the last 10 dont, changed the bulb etc no luck, shorted the terminals of lampholder 31 (the first one not working) still no luck. Why???? In a series circuit removing a bulb the whole circuit stops!!! But surely there is no in between. In frustration removed the lampholder 31 and crimped the cable back together bypassing the holder. Still no luck. Any ideas?? Dont want to take tham back as they are wrapped around a 30ft high tree!!

David

 

[plugwash]

i'd guess a short in the wiring somewhere

 

[David E]

Dont think it can be a short as they are on a multi stranded "loom"

 

[Steve]

What makes you think its lamp 31 thats the problem??? Heres what im thinking:
you lamps are wired so each circuit is divided into 4 sets of 10, thus 16 total sets, 160 lamps.
Circuit D has 4 sets wired in parallel to each other. One isnt working.
One bulb has gone, so they have all gone out, due to cheap lamps having no bypass.

incidentally, what made me think this is we have a set of icicle lights that have a set not working The wiring is so complex its unreal, but the first 10 drops have one circuit not working, but the rest of the drops have all 4 circuits working. Only 5 wires leave the controller. Unreplaceable lamps too.

 

[Lectrician]

Yup, 4 channels, but 4 sets of series circuits per channel.

At the intersections between series groups, you will see holders with 3 cables.

It will be a blow bulb in the set that is off, or a badly fitted one. Could also be a dodgy holder.

taking a lamp our of circuit, and crimping the ends will cause each lamp in that group to recieve more volts than the rest....and cause them to blow early!

 

[David E]

Thats right 4 different series circuits - 3 work fine and the 4th 75% of the bulbs work but the last 25% don't. How can that be in a cricuit wired in series when the circuit is dependant on the "ring" being maintained? Lamps 1-30 are OK 31 to 40 don't work. I take your point wth the over voltage issue, at the moment the lights are out until I can sort them out, but hopefully the 1 I removed and crimped out of the 40 is only just over 2% increase, haven't a clue as to the toleance hopefully this is not too great!!

 

[Steve]

on that circuit D, you have 4 sets of 10 in parallel.

now do you understand?

 

[David E]

Not parallel series.


__x__x__x__x__!!!!!!! Series


_____________
x x x x parallel
_____________

 

[ban-all-sheds]

No - you are wrong, and have been throughout. Crafty's drawing is quite correct.

Should you really be doing this if you understand so little about the basic theory behind it all?

160 24v 0.25A outdoor multifunction lights ie 4 circuits in series each of 40 bulbs

OK - 4 separate sets, A, B, C & D. But surely you have wired each set in parallel?

Circuit A, B & C are fine, D works for the first 30 bulbs but the last 10 dont, changed the bulb etc no luck, shorted the terminals of lampholder 31 (the first one not working) still no luck. Why????

Because there is something wrong with the last string of 10 lights.

In a series circuit removing a bulb the whole circuit stops!!!

Yes, and that is what has happened here!!! The last set of 10 lights in series is faulty, somewhere, so they all go out!!!

The first 3 sets of 10 are OK, so they light up.

But surely there is no in between.

Well, if considering each 40-light set as one entity, there is.

Series-parallel:

Each of your 40-light sets has 4 strings of lights in parallel, and each string has 10 lights.

It's incredibly simple to understand, it fits perfectly with the fault you describe, and if you still don't believe what we are telling you, try doing some simple maths:

160 24v 0.25A outdoor multifunction lights

What is 160 x 24?

What is 40 x 24?

What is 10 x 24?

What is the domestic supply voltage in this country?

Which result above is closest to this?

So how many lights are in series in each set?

 

[Lectrician]

I entirely agree bas, except the voltage issue....

I suspect the set operates from a 24 transformer, so the lamps will need to be 2.4 volt each.





Perhaps David-E could look at the spares and find out! That would prove the 24 devided by 10

 

[ban-all-sheds]

Well, I'm just going by what he said....

 

[Allenm]

Sounds to me like more than 1 bulb has gone in the last set. I had the same trouble yesterday. Simple to resolve.

(ONLY FOR LOW VOLTAGE SETS)

Light the set in steady lit state.
Remove a working bulb away from the suspect set.
Remove each bulb from the suspect set one at a time and test the bulb in the (known to work) socket, if it don't light up - change it.
Keep going until the set lights up.
If it doesn't, you have a dodgy socket or wire. Take a trip to the shops and buy a new set.

 

[Steve]

Sounds to me like more than 1 bulb has gone in the last set.

how d'you work that out? Have you been reading this thread at all???? ONE BULB HAS GONE on the 31-40 chain of series-ly wired bulbs, causing them to go out. If, after a bulb has gone out, none of the others can light, how does another blow? Simple, it cant, until the chain is working again, unless the filament just magically breaks or the bulb is smashed.

DavidE, look at the bulbs closely on that set not working, you might be able to see the one thats broken.

 

[1974stephen]

B&Q are open 'til 9pm. They sell new sets of lights. Go there.

 

[ban-all-sheds]

hopefully the 1 I removed and crimped out of the 40 is only just over 2% increase

The one you removed and crimped out of the 10 means an 11% increase on each of the others....

B&Q are open 'til 9pm. They sell new sets of lights. Go there.

E's gone a bit quiet....