dead short L-N but the fuse doesn't blow?

[ExArmy]

when doing an inspection i came accross a radial circuit serving 4 points, the IR between L-N @500V was 0.00 Mohms, on continuity between L-N I got 25 ohms. when I then energised the circuit and clamped the live, no current being drawn. I have yet to take any fronts off as it was just an inspection and i didn't want to start faultfinding, i'm almost certain i got the whole of the circuit and everything was unplugged and they were just plain 2G sockets with no neons, but this one has baffled me. surely if the reading was that low, then there would be about 10A being drawn?

 

[Octopus]

Shaver point? (but this wouldn't be 10A)

 

[DurhamSparky]

NEON ina hidden extension.....??? appliance connected.... tv amp in loft!! ???

 

[Spazz]

You have a light plugged in, could be a lamp, neon on a FSU, (check emersion heater), shaver point if on lighting circuit

keep looking and you will find something!

I did come across a FSU the other day hidden behind a false wall, home owner extended a ring with a FSU.

 

[Octopus]

Outside light?

 

[ExArmy]

shaver point! i don't know for sure, but this seems likely as the radial is for a hallway, utility and bedroom right next to the bathroom. it's there is no loft, just really high ceilings so it can't be that. i'm back there this week sometime i'll investigate further

 

[Octopus]

If its next to the bathroom do they have a heated towel rail?

 

[Spazz]

If you completely fail to find it try breaking the Radial down (removing sockets), that way you should be able to get a rough location.

 

[Knobhead]

Next-door neighbours illicit grow room? (Oh No not that subject again)!

As the others have said you’ve overlooked a load somewhere. Let the hunt begin.

Are you going to tell us what you find?

 

[tony mc]

Lets hope when you do find it the item will still work after having 500 volts passed through it !

 

[Octopus]

Immersion heater?

 

[imago]

Have a look under/in any wall cabinets for lights.

 

[JD6400]

A TV booster would be the one I'd bet on !?

 

[plugsandsparks]

mmm trying to think of a load that gives a 25ohm dc resistance but could be much higher impedance on ac. It could be a big heater load like an immersion or it could be a small electro-magnetic load like a shaver point or motor of some type. Dont know what the dc resistance on a fluorescent light but suppose its around that amount.

Good Luck and lets have a pic of the offending item

*hite just spotted no current drawn ? (or very small for your meter) Shaver point for me

 

[MarkieSparkie]

My bets on an immersion heater hidden in a cupboard.
An immersion heater in a tank of hot water is favourite:- 1) When you tested the insulation the hot water in the tank was below the set temperature and the thermostat was therefore ON presenting a load. 2) When the final circuit was re-energised, the hot water quickly rose above the set temperature switching OFF the thermostat and disconnecting the load before you had clipped the clamp meter on to monitor the load current.

 

[SPARTYKUS]

Underfloor heating?

 

[AIM]

Door bell transformer, boiler plugged in, in a cupboard, PIR light, alarm spur, forgotten mobile phone charger plugged in behind bed headboard. These are some I've found recently.

I always do IR at 250v first. L - N value of 0.2 - 0.3 MegOhms usually finds a neon or load plugged in somewhere.

 

[soulman]

I would be careful testing between L-N at 500v on an inspection, you may find yourself in trouble if you fry something! I would always test LN-E global at the board and if the result was satisfactory record that for all circuits. If the reading was low then maybe break it down, if you really want to test l-n, soft test at 250v first. I had poor readings about a month ago it was an old mobile charger plugged in, socket hidden the wardrobe.

 

[tony mc]

when doing an inspection i came accross a radial circuit serving 4 points, the IR between L-N @500V was 0.00 Mohms, on continuity between L-N I got 25 ohms. when I then energised the circuit and clamped the live, no current being drawn. I have yet to take any fronts off as it was just an inspection and i didn't want to start faultfinding, i'm almost certain i got the whole of the circuit and everything was unplugged and they were just plain 2G sockets with no neons, but this one has baffled me. surely if the reading was that low, then there would be about 10A being drawn?

Are you any further forward with tracing the above?

 

[ExArmy]

not been back yet, as soon as i know i will update the thread

 

[sparks1973]

Next-door neighbours illicit grow room? (Oh No not that subject again)!

As the others have said you’ve overlooked a load somewhere. Let the hunt begin.

Are you going to tell us what you find?

could be something communal eh Tony...lol...

 

[ExArmy]

went back today, explained why I was back and said there must be something hidden somewhere that i'm missing as I'm getting a dead short L-N. both of them and me ratched about for 5 minutes before giving up, they were adamant that there was nothing else there. and then just as i got in the van i noticed a light on the outside shed, went back and knocked on the door "theres a light here on your shed, is there power to it?" and the guy replied "yeah thats where the freezer is" !! so then he opens up the shed and theres a double socket of the radial, and a light off the main lighting circuit. so I tested them and they were ok. mystery solved! now i can sleep at night.

 

[Des 56]

I gave you a thanks for being polite and returning to your thread with the outcome.
Its an action demonstrated less and less lately

 

[SPARTYKUS]

Ex army

As Des says, "respect"

 

[1shortcircuit]

Well done ExArmy and thanks for the update :thumbsup

 

[Dipzy]

Yep, defo thanks for the update :rockon2: