40W drawn on lighting circuit even when everything is off

[crappy]

Folks,

I noticed - with a tong tester - that one of my lighting circuits is drawing a steady 40W.
When I turn the breaker off it stops.

For the life of me I cannot find any light turned on or bathroom fan on.

There are two 1.5mm wires going into the A mcb.
No smart or dimmer switches.

I care because I recently moved, got shoved onto a 41.5p/kwh rate and this is costing me 50p per day. I'm hemorrhaging money with electric and fuel oil now at £1.23 / L!

How best to find this?

 

[EFLImpudence]

I noticed - with a tong tester - that one of my lighting circuits is drawing a steady 40W.
When I turn the breaker off it stops.

Never heard of a 'tong tester' but search says it is a clamp meter.

There are two 1.5mm wires going into the A mcb.

Firstly, take out the one which shows the 40W and see what stops working.

 

[jj4091]

Never heard of a 'tong tester' but search says it is a clamp meter.

I've always known a clamp meter as a Tong tester, you must be a relative youngster

 

[BS3036]

Well, I guess that can only measure current, and the 40W assumes 230/240V (174mA). It doesn't take into account power factor. So something like a permanently connected power supply with no load connected may be able to give this, but usually lighting 'transformers' are switched at the input so it doesn't sound very likely.

 

[securespark]

I started in 1983 and have never heard of it either!

 

[JohnW2]

I've always known a clamp meter as a Tong tester, you must be a relative youngster

I've never heard EFLI being accused of that - after all, he is 'retired'

Kind Regards, John

 

[JohnW2]

Well, I guess that can only measure current, and the 40W assumes 230/240V (174mA). It doesn't take into account power factor. So something like a permanently connected power supply with no load connected may be able to give this, but usually lighting 'transformers' are switched at the input so it doesn't sound very likely.

Indeed. If it really is anything like 40W, that's rather a lot for any of the diddy electronic things that can easily be 'overlooked'.

An obvious thing for the OP to try to ascertain is what, if anything, (other than lighting) stops working when he switches off the MCB - things like modems/routers, aerial amplifiers, alarms, 'chargers' etc. come immediately to mind.

Kind Regards, John

 

[oldbutnotdead]

CCTV? Burglar alarm? Broadband router, RF distribution amp, loft lights, outside lights, posh video doorbells..
The electronics (distro amp, doorbell camera) individually won't do 40w but they do add up.
I'll put a quid on it being either the loft (or airing cupboard or wardrobe or understairs) light left on or there's an outside fitting in a walkway somewhere that you're paying the power bill for.

 

[sparkwright]

Yes, I was thinking a loft light, or if this is a flat, a communal light or something. Or a towel rail or boiler or something.

Or even something belonging to your nextdoor neighbour!

I have heard and seen of a clamp on tong tester.

 

[crappy]

loving the debating over tong/clamp tester. If it helps I've heard of both, interchangeable of the names, and I'm not even a sparky

ok, so I turned the mcb off and walked around the house and notice nothing untoward. What is interesting though - see below - is that I put a split-core CT (we all heard of them? ) and logged the usage every second.
it does seem to dip down to 20W rather than 40 and then back up. That small dip at 18:25 I was not home but it's so small it could be noise.
You can see from the whole graph though that it's pretty steady but has defined dips of 20W...... I guess I have two of them then


PIR lights - I have them - none on.
Aerial amp and distribution - that is plugged into a socket (confirmed - on one of the rings).

I will continue to search and see what I can find....

could it be this?

 

[flameport]

PIR lights - I have them - none on

The PIR sensor uses energy even if the lights are off.

 

[oldbutnotdead]

The PIR sensor uses energy even if the lights are off.

Aye but 40w would be a bit OTT for a passive sensor. @crappy do continue the quest- i'd suggest if you find nowt then check the individual lives on that MCB- if one of them only has that mystery load on it then either disconnect it or put a periodic timer on it (so it cycles off and on every 15 minutes) an wait for gossip from a neighbour about how their telly drops in and out every 15 mins