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Please help me

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Impact

New Member
Thought this site would be the best way to get an answer that has been on my mind for some time now.
I use to have some break-out boxes which turned on a neon when the fuse blew, but because it's been sometime since I've built some, I've lost the wiring diagram and wanted some help.
The way I remember doing it was to use a resistor across the live and neutral of which when the fuse blew would drag the supply to the neon, but I carn't remember where the resistor went and what value it was.
The unit consisted of 4 IEC cables, 4 coloured neons, 4 fuses and 2 blue 16 amp plugs.
The reason for me wanting this unit is to be put onto disco/stage lighting rig, so that I can fault find at a glance whether a unit has blown a fuse or is faulty in some other way.
I know alot of you will say use a relay and switch the mains to the neon when the fuse blows but I've thought of that already and the size of box I want to use will not allow for it (plus I would have to build a PCB for it anyway)
Any help on this matter would be gratefully recieved.

Many thanks
 

john1

Active Member
Hi Impact,

The neon and resistor would have been across the fuse.

That might be illegal nowadays, because it uses the live side through the
load. However, it would not be illegal to use the lives of the fuses that
have not blown.

I suggest that you put neon (or other) indicators on the feed sides, then
if one goes out that would indicate a loss of supply.

That would not involve any live connections going to the load side of a
blown fuse.

You would have a row of lights, rather than one lit when a fuse blows.

There is one other arrangement that used to be used by the GPO, thats
where the fuses were wire fuses, and a small spring was pulled down using
the fuse wire, when the fuse blew, the spring returned and put a feed to
a lamp. That was low voltage only.

Hope this helps.
Regards, John :)
 

Impact

New Member
reply

Hi john,

Thanks for the reply.

In answer to your reply about running the neons so that they are lit all the time and when one blows it will got out, I did not want that to happen mainly due to the fact that if the lighting rig is up in the air in a very dark place, then the eye will be attracted to the neons and would make it harder to find the fault (i.e all neons lit in a dark area would be harder due to the boxes being small black ones, and they would be high up).
If the neons illuminated when the fuse blew etc, then the neon would light up and would be easier to find due to the fact that there would only be one light on the box for each break out mains.

Once again thanks for the reply, and if you can shed any more light on the subject then I would be grateful.
 

mechie

New Member
Fuse Fail Indicator

This is what you want.
The neon will want a series resistor of a few hundred kiloOhms,
this may be built into the little panel indicators if that's what you use,
either way, the resistor is calculated to suit the mains voltage you are on
and the current required by the neon bulb you choose - some need more
current than others !

The indicator will obviously only light when the fuse blows AND there is a load connected
:wink:

I think this kind of indication is just as legal (in the UK) as those horrid
little screwdrivers that have neons in the handle and use your finger as
the current return path to earth (fine as long as they work properly).
Klippon used to make terminal rail fuseholders with neons in for just
your application.
 

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Roff

Well-Known Member
Re: Duplicate thread !

mechie said:
Nice one Impact...

This thread is duplicating https://www.electro-tech-online.com/threads/website.3253/

So which one do we follow ???
I'll pick this one because it has a schematic I can refer to...
On the remote possibility that there is no load connected - let's say you plugged an appliance into an otherwise unused circuit, the appliance didn't work, so you unplugged the appliance and went to check the fuse - then the neon will not light because there's no load even if the fuse is blown. Otherwise, I think this is the simplest solution.
Another thought. A 100nF capacitor connected across the load terminals would provide a current path for the neon bulb without wasting any power.
 

Impact

New Member
Hum

:D Thanks guys for the answers proved, during this link.

In respect of the other link on another thread, this is due to a remote chance that there maybe other solution to the resistor problem.
 
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