The strangest thing: Calling all Sherlock Holmes

[rjb]

Just watched a local BBC story about a little old lady who when she switches on her kettle the street light goes out and visa versa.

Any ideas?

Additionally, any one ever had a complete electrical mysteries ..and maybe the cause and solution if you worked it our.

http://news.bbc.co.uk/1/hi/england/northamptonshire/7028021.stm

 

[Adam_151]

Only thing I can come up with on a friday evening is: its TNS, the sheath has degraded quite a bit and its high resistance, the kettle is wired phase-> earth by mistake, and a contactor for the streetlamps is wired with the same error, the kettle causes phase-earth voltage to collapse quite a bit and the contactor drops out.

Unlikely, but probably only as much so as the next!

Onto the other part of your question, I was once interfacing a circuit to a computer's parallel port, But when I connected it to the bench supply, it arced a tad and the display went dead found it had blown a fuse underneath (this was strange, as its all electronically protected, and you can quite normally happily connect it across a direct short and it'll just illuminate the overload LED and drop the voltage down to such a level that the current drops below 2A). Anyway, played with it somemore and blew another fuse, eventually tracked the fault down to the fact that a wire had rubbed against another where it goes through to a component on the back heatsink, it was +ve of the elv that must have been before the protection circuitry had become shorted to the CPC for the case, this didn't present an issue untill I tied the gnd to the gnd of the computer, which ties its gnd to earth, so it was shorting the psu out through the CPCs of the computer and bench psu!

 

[rjb]

Oh! STOP PRESS for all you Great Billing street light fans out there.

The spotty youth faced electrician/technician just shugged his shoulders and has given up!!

 

[bernardgreen]

Some lights are controlled by a "spike" added to the supply along the road from the "master" lamp.

It may be the kettle has been adding a spike to the mains which the street lights see as a command signal.

Very un-likely but so far the only idea I can think of.

 

[ricicle]

How about the supply cable for the house and street light are common and are on the same phase.This set-up is right at the end of the cable run and when the kettle is switched on it causes an already low voltage to drop below the level required to maintain the discharge in the streetlight.
When the kettle is switched off the voltage rises again slightly enough to re-strike the lamp.

I havn't seen the story so don't know the set-up or if this happens with any of her other 'power-hungry' appliances, but being an old lady she might not have an electric shower, tumble drier etc so a kettle might be her greatest load?

 

[Adam_151]

Some lights are controlled by a "spike" added to the supply along the road from the "master" lamp.

X10 ?

 

[Coniferman]

Sounds like one of those stories you hear about certain people that when they walk down the road, the nearest light goes off and when they get past it comes back on again.

When you go to investigate (not that I have done personally) you find that that light is randomly going on and off all the time and actually has nothing to do with the person walking past.

 

[streetlighter]

Yeah i watched a programme on Discovery about street lamp interferance syndrone. They had a lighting expert from David Websters explaining that when SON lamps reach the end of there life they start to flash on and off.

 

[Space cat]

I've read the article and it says "lights", as in "the lights along Trussell Road". This pretty much rules out any theories about voltage drops or old lamps.

As Sherlock himself would have said, "When you have eliminated everything else, whatever is left, no matter how improbable, must be the truth" so bernardgreen is right. When she switches on the kettle it generates a transient which mimics a control signal for the lights.

 

[rjb]

As much as you can believe the BBC these days (socks the blue peter cat etc etc) only one street light was affected that was right outside her house. With the aid of a walkie talkie or mobile phone the reporter was outside under the light at night and with a "all right turn it on" and as if my magic the street light sure enough turned off and visa versa.

Perhaps she's an expert electrician and either a) wants the publicity so imagined up a plan too good to wait for 1st April or b) abstracting a bit of electricity courtesy of the Northants county council. (last point is mearly a possibilty aka elimininating all possibilities mentioned in earlier post - not suggesting the old dear is a tea leaf!!)

 

[THRIPSTER]

The kettle wiring is wired in series with the street lamp?

 

[gcresser]

I like the way the guy from the DNO is wearing his glove told hold his tester, but sticks the probe in with no glove!

Also I'd say the shot with the light coming on at dusk is not the same streetlight - it is striking up red like a SOX. The one outside her house is a SON.

Anyway, enough of being picky, here's what I think:-

The lamp is T'd off her service. Bit of a dodgy kettle that causes a slight voltage drop which is enough to drop the voltage below the required amount to run the lamp/choke. Does the lamp come back on? If not then there is possibly a timed ignitor in the lantern which wont kick in until the supply has been interupted.

 

[Lectrician]

Thats my thought too.

I have read the story in several places, not seen any footage. Everytime I read it it is slightly different.