# Forum Home Renovation Lighting  Electrical lighting circuits

## stcos85

Just moved into a new property and a bit confused by the lighting circuit at the switch. It has the live from the supply and the return to the light but there is another cable with one wire connected. Anyone know what that is.

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## Bedford

Some pics might help if you can post them.

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## stcos85

> Some pics might help if you can post them.

  
Basically its got 1 red and 1 white wire from 1 cable and a white wire from the 2ndcable with the red not terminate. The 2nd white wire is in the loop terminal

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## Bros

> Just moved into a new property and a bit confused by the lighting circuit at the switch. It has the live from the supply and the return to the light but there is another cable with one wire connected. Anyone know what that is.

  And why would you be poking around inside the light switch?

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## stcos85

The switches are cracked so want to replace them with new ones and am curious what the extra wire might be

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## Bros

As Bedford said some pics might help but you are in unknown territory .

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## dgp

There could be a few possibilities. The white in the loop has been terminated so could be a hard active ( although it should be red), there may have been two switches there at one stage. 
I have seen some dodgy stuff over the years and mostly due to DIY sparkies and also sparkies who, quite frankly should not be called tradesman. 
Call an electrician in for a look.

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## stcos85

> There could be a few possibilities. The white in the loop has been terminated so could be a hard active ( although it should be red), there may have been two switches there at one stage. 
> I have seen some dodgy stuff over the years and mostly due to DIY sparkies and also sparkies who, quite frankly should not be called tradesman. 
> Call an electrician in for a look.

  It looks like there are 3 light switches like this and they are in the downstairs bedrooms. 
The lighting circuit is fed from a secondary distribution board which is fed from a 16 amp breaker in the main board. Could this be the reason why it is wired differently

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## dgp

No.
The loop terminal is basically only there to either join cables or safely terminate a cable that is not being used right now. Be very carefully, it could be live. 
You do know that if you are not licences to undertake this work that you are breaking the law don't you?
BUT, even more importantly, you could die. It only takes 0.8 amps to kill a person, you average electric kettle draws 10 amps.

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## chalkyt

We can all guess... disused two way switching, feed to another light etc, etc. But, you need someone who can determine exactly what is going on. As boring as it sounds, this is a case for "call the electrician". As dgp says there are lots of strange things out there and proper testing for what is active, what is not, etc is the only way to find out.  :Smilie:

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## stcos85

> We can all guess... disused two way switching, feed to another light etc, etc. But, you need someone who can determine exactly what is going on. As boring as it sounds, this is a case for "call the electrician". As dgp says there are lots of strange things out there and proper testing for what is active, what is not, etc is the only way to find out.

  Decided to get an expert in. These switches look like they are from the 70's so I would expect the circuits have been working as they should since then but better to get professional opinion. I am also renovating close to this area so may just get it all rewired while there is some mess in the house. 
Just need to find someone local to me that wont rip me off

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## Whitey66

> No.
> The loop terminal is basically only there to either join cables or safely terminate a cable that is not being used right now. Be very carefully, it could be live. 
> You do know that if you are not licences to undertake this work that you are breaking the law don't you?
> BUT, even more importantly, you could die. It only takes 0.8 amps to kill a person, you average electric kettle draws 10 amps.

  Actually it's way less than 0.8 Amps, as little as 50mA through your heart can put it into fibrillation (0.05 Amps) if the duration is 1 to 2 seconds or more.
This is the reason RCDs must trip at 30mA . 
It is important to remember that it's not only the amount of current flowing through the body,but also the length of time that does the damage.

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## oldtrack123

> Actually it's way less than 0.8 Amps, as little as 50mA through your heart can put it into fibrillation (0.05 Amps) if the duration is 1 to 2 seconds or more.
> This is the reason RCDs must trip at 30mA . 
> It is important to remember that it's not only the amount of current flowing through the body,but also the length of time that does the damage.

  HI Whitey  
Ditto
And the voltage does not need to be very high under the right or i should say wrong situations
I have seen serious harm done by prolonged shock with 32V AC
TWO Deaths with 72V AC!!    
it is the actual conditions that determine the current passing through the body  
PeterQ

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## Bros

A welder can kill. I had a second cousin who I never knew who was welding in the smoke box of a steam locomotive. As welding cables are heavy and restrict the movement of the handpiece  boilermakers used to wrap the cable around their bodies to control the weight on the handpiece. 
Well this happened in North Queensland where it is hot and he started sweating and you can guess the result as the cable insulation was rubber.

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## Bedford

Yep shocking stuff, there oughta be a law against it.

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## dgp

> Actually it's way less than 0.8 Amps, as little as 50mA through your heart can put it into fibrillation (0.05 Amps) if the duration is 1 to 2 seconds or more.
> This is the reason RCDs must trip at 30mA . 
> It is important to remember that it's not only the amount of current flowing through the body,but also the length of time that does the damage.

  Woops I meant to say 0.08 amps but point taken  :Smilie:

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## michael_sa

> Actually it's way less than 0.8 Amps, as little as 50mA through your heart can put it into fibrillation (0.05 Amps) if the duration is 1 to 2 seconds or more.
> This is the reason RCDs must trip at 30mA . 
> It is important to remember that it's not only the amount of current flowing through the body,but also the length of time that does the damage.

  There's an old saying: "It's the Volts that jolts, but the mils (as in milliamps) that kills"

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## oldtrack123

> A welder can kill. I had a second cousin who I never knew who was welding in the smoke box of a steam locomotive. As welding cables are heavy and restrict the movement of the handpiece boilermakers used to wrap the cable around their bodies to control the weight on the handpiece. 
> Well this happened in North Queensland where it is hot and he started sweating and you can guess the result as the cable insulation was rubber.

  
HI Bros 
That was the situation with the two 72V deaths in both cases the welding lead was drooped over the shoulders &across the back of the neck, inside a  large pressure vessel[hot& sweaty] 
The 32v was from a hand light while working in the propeller shaft of a ship
The bloke fell down between the ribbing & was there for about 10mins before he was found,a nice wet area again with the lead around the neck!!
Having seen all  three, is enough make me shudder when ever see anyone with a lead  wrapped around any part of their body!! 
PeterQ

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## Whitey66

> HI Whitey  
> Ditto
> And the voltage does not need to be very high under the right or i should say wrong situations
> I have seen serious harm done by prolonged shock with 32V AC
> TWO Deaths with 72V AC!!    
> it is the actual conditions that determine the current passing through the body  
> PeterQ

  Hi Pete! 
I know exactly what you're talking about with the 32v AC.
We used to have 32v AC leadlights in our workshop and a lot of the mechanics thought it was only 32v so it couldn't hurt them,despite the advice from their older and wiser workmates.
While it did provide some entertaining dancing and cursing when someone "got bitten", luckily no serious injuries occurred.
I'm not sure of the amperage or wattage these things ran at,but they were as bright as a 100w - 240v bulb.
A quick calculation on a 100w - 240v bulb =  about .42A or 420mA
If the 32v bulbs were 100w - 32v =  about 3.13A  - about 7.5 times more current than the 240v bulb  :Shock:

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