Neon on fused switch

[phil1235]

I've inherited a light switch on a spur from the downstairs lighting ring which operates a garage fluorescent light and a 500W outside PIR security light from a switch in the kitchen by the door to the garage. (Can't access the wiring to separate them, but not a problem as the security light is used only for convenience to light the driveway). I thought it would be better to give this separate protection with a fused spur switch fitted with a 5A fuse - also with a neon (actually a LED) as a reminder, as my wife keeps leaving it on. Being on a spur there's only one 3-core cable coming in to the surface box. So I've connected the red wire to L input and the black wire to L load (and the earth of course). Lights work, but the neon doesn't come on. Presumably the neon would be powered by a potential difference between L load and N load.

Could I get the neon to work safely by connecting the unused N load to earth, thus providing a potential difference? The lighting circuits in the house are on an old consumer unit with pop-out fuses and no RCD. (All the power circuits are on a separate modern consumer unit.)

 

[AdrianUK]

Could you- yes. Would it work - yes.

Should you - NO. Is it safe - NO!

 

[Iggifer]

Does the neon work if you connect it to the supply side? You might just need to take it out and put it back in the terminals again.

You don't say whether the neon has it's own little terminals or just screws into the load terminals with the cable, but I've come across issues with both types just not making a good enough contact with the neon

 

[ban-all-sheds]

I've inherited a light switch on a spur from the downstairs lighting ring

It is not a ring.

• http://www.google.co.uk/search?q=electrical+circuits+(basics+OR+101)
  
  
• http://www.google.co.uk/search?q=uk+house+wiring+(basics+OR+101)
  
  
• [wiki]Electrics%3ALighting[/wiki]

I thought it would be better to give this separate protection with a fused spur switch

Why?

fitted with a 5A fuse

The lighting circuit is practically certain to be on a 5A fuse or a 6A MCB. What do you think is the point of a 5A fuse in the FCU?

Could I get the neon to work safely by connecting the unused N load to earth

No.

 

[ban-all-sheds]

Does the neon work if you connect it to the supply side? You might just need to take it out and put it back in the terminals again.

You don't say whether the neon has it's own little terminals or just screws into the load terminals with the cable, but I've come across issues with both types just not making a good enough contact with the neon

Iggifer - I am become increasingly concerned about the quality of your advice.

There's no neutral at this switch - the indicator lamp is not going to work no matter how sound the connection to line is. Or which side of the switch it's connected to.

 

[JohnW2]

Does the neon work if you connect it to the supply side? You might just need to take it out and put it back in the terminals again. You don't say whether the neon has it's own little terminals or just screws into the load terminals with the cable, but I've come across issues with both types just not making a good enough contact with the neon

I think you're perhaps missing the point. It appears that the OP is using a DP switch with neon for SP switching of the light, and does not have a neutral available at the switch - he is therefore asking whether he can/should wire the neon from S/L to earth. He's already been give an answer to both those questions ("can" and "should")!!

Kind Regards, John

 

[AndyPRK]

The only allowable method would result in the LED being on when the switch was off.

Is that any use ?

 

[Iggifer]

Ohhhh yea totally missed that bit. Yea ignore my advice

 

[JohnW2]

The only allowable method would result in the LED being on when the switch was off

Hopefully With just the garage fluorescent (if it's an 'old-fashioned' one) it presumably wouldn't work, but the PIR might do it!

Kind Regards, John

 

[Iggifer]

Iggifer - I am become increasingly concerned about the quality of your advice

I'll keep giving it and you can become as concerned as you like

 

[ban-all-sheds]

And if you keep on telling people to do things which are dangerous then I, and hopefully others who share my concern about things like that, will do our best to get you shut down.

 

[phil1235]

Thank you, everyone, for your replies. (Sorry about delay - have been away for 3 days.) Having looked at the diagram on the DIYnot page flagged up by ban-all-sheds, I can see that the Fluorescent and PIR are in parallel from the one switch on the downstairs + garage lighting circuit - forgive my ignorance. With the number of lights on that circuit overall (4-bedroom house) I had assumed that the old MCB would be more like 10A, but having crawled in under the stairs with torch & reading glasses I see it's 5A. Main requirement was for a warning light that garage light was left on, but options seemed to be a hefty 20A DP isolator switch or a fused spur switch - hence the fuse. Thought I'd make a virtue of necessity with the fuse, so that if the 500W PIR or 60W garage fluorescent gave a problem it wouldn't trip all the downstairs lights. I guess I could put a 3A fuse in the fused spur switch, but wondered whether a surge would pop it too easily. Not sure whether the switch is SP or DP; it's a Powersmith LAP item from Screwfix (86756) - no mention of BS1363 on the box or leaflet. The LED is built in to the switch - not accessible. Having the LED lit when the lights are NOT on would not achieve anything, I'm afraid (even if she'd take any notice of it if it's on when the lights are on). Looks like I'm wasting my time?

 

[Iggifer]

Why not just stick in a time lag switch? Set it to 20 minutes or whatever, then you can't forget to turn it off - I don't know if this would suit - don't know what you use your garage for.

You could put a 3a fuse in there, but as to whether the 5a or the 3a fuse would operate first in fault conditions is anyones guess. It could be either or, both. I wouldn't bother personally.