Dodgy wiring

[hightower]

Been speaking to a neighbour who had an outside light installed a couple years ago. Apparently the light worked for a while.

The 'electrician' apparently wired the neutral for the fcu to the switched line of the ceiling rose. I'm guessing the line of the fcu was wired in to the permanent line of the same ceiling rose, but my neighbour didn't gave that info, only about the neutral.

I haven't had chance to draw this out and I'm having trouble visualising it, but I can't see how it worked for a while.

Think I'm gonna need to draw it out. ..

 

[Dave OCD]

With the light it was fed from switched off there may have been a return path of sorts back through other lamps in the circuit -possibly.

 

[Pete999]

You need to have a look mate, never trust heresay

 

[hightower]

You need to have a look mate, never trust heresay

It was rectified a few weeks after it was done. It's a new build so BETT came to have a look 2 years ago, and that's the note they left her, that the neutral was wired to the sw line.

Doesn't mention the rest of the wiring, but really struggling to see how it would work at all.

Apparently this error has voided her warranty on her new build though.

 

[PEG]

Who is the warranty with? Coz i have pals whose new-builds included wrong sewer connections,roofs with MC Ischer gutters,non-functioning drains,bio-filters,and much,much more...and they never incurred a voided warranty...

 

[happysteve]

Second rule of Steve: "If in doubt, draw it out."



Pretty sure you're smart enough to work it out from that, assuming you can read my scrawls!

I've made assumptions about the rating of the internal (100W) and external (10W) lights. Essentially, the voltage across the external light is related to the ratio of the consumption of the two lights. If they were both 10W, then there would be 115V across the external light.

In the scenario above, 209V is plenty to light up the exterior light, whereas 21V probably won't even make the internal light glow.

All appears to work, until the customer turns on their internal light. At that point, the exterior light turns off.

Hope that's useful, anyway!

 

[GETWIRED]

Suppose that spark was having a bad day lol

going to open myself to flak here but applying the theory to that fault is pretty brilliant..

 

[hightower]

Thanks steve, you always seem to come up with the goods

 

[hightower]

Who is the warranty with? Coz i have pals whose new-builds included wrong sewer connections,roofs with MC Ischer gutters,non-functioning drains,bio-filters,and much,much more...and they never incurred a voided warranty...

It's a BETT home but the additional light was done by a local electrician. My neighbour caked bett out when things started going wrong and they said the warranty was no more because of the incorrect wiring

 

[hightower]

Second rule of Steve: "If in doubt, draw it out."

What's the first rule of steve?

 

[happysteve]

What's the first rule of steve?

First rule of Steve: don't talk about the Rules of Steve.

 

[hightower]

I've just redone the maths because the outside light was this model: 120W Anti-Light Pollution PIR Floodlight - Black

Outside Light:
P = 120w
V = 104.4v

Inside Light:
P = 100w
V = 125.6v

Would those voltages be enough to power each to some degree?

 

[telectrix]

if the N of the outside light is connected to a switched L, then if the switched L is not energised, it's seen as a N by the outside light as it has no potential. this is how location indicators on switches work. they'e ON when the switch is OFF and ON when the switch is ON.

 

[hightower]

if the N of the outside light is connected to a switched L, then if the switched L is not energised, it's seen as a N by the outside light as it has no potential. this is how location indicators on switches work. they'e ON when the switch is OFF and ON when the switch is ON.

Yeah but in this case the outside light is in series with the inside light, and the voltage applied to each light isn't the full 230v. As Steve said, if both the fittings were near the same then they would equally share the voltage. When the switch is turned on the outside outright wouldn't work, but what would happen when the switch is off if both lights had 115v each? Would it be enough to power both but dimly? If so, how didn't my neighbour notice the bedroom light was constantly on?

Or would it mean the bedroom light would only come on when the PIR triggered? She can see the outside light works, but doesn't realise there's a disco happening in her bedroom since she's outside triggering the PIR.

 

[telectrix]

could well be that. the voltage shared between the 2 lights in series. a lot of LED drivers have a large voltage tolerance, some around 90V to 240V