Weird electric issue - phantom bulb using watts

I’m new to having a smart meter and did the dad thing of turning everything off to see what uses what watts.

If I flick the CU switches off so that everything is off but the upstairs lights I have the meter showing that theres 10-12W in constant use.

That’s with the lights all turned off. :sweat_smile: It’s about as much as a 100W equivalent LED bulb being permanently on.

Any sparks know what could be the reason? Could dodgy wiring be pulling that much?

If I do the same with only the downstairs lights flicked on the CU and the lights off then it’s 0W as expected.

Do you have any WiFi bulbs installed on the upstairs lighting circuit? (with the CU upstairs circuit on, even if they are OFF, they are consuming a little power)

Without inspecting your installation, is there a possibility someone has tapped into the upstairs lighting circuit to power something else?

Do you have a loft/attic light which has been accidentally left on? (that you can’t see unless you go up there)

Do you have lights on a dimmer, and the dimmer is down at zero, rather than OFF? The dimmer switch will still pull current.

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IME a TV aerial amplifier in the loft is the most common non-bulb addition to an upstairs lighting circuit


It could also be capacitive coupling on the long cable run for a two-switch light, but it seems a bit too high for that.

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Any outside lights?

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Definitely not the WiFi bulb as I took them physically out.

The main bedroom is dimmer but made sure it was pressed off

I also had checked the attic. We haven’t used the attic since moving in about a decade ago so I was going to be laughing if it was on.

Nothing outside.

The house does have an alarm system on the downstairs rooms. Not sure how that’s wired in :person_shrugging:

It doesn’t have a breaker for alarm, I guess that’s so one doesn’t ninja there way to it and flip the security off so guess it’s in the attic.

Just noticed with sockets on the CU its showing 6W in use and that’s with everything off but I can’t reach to the sockets that have two power extensions to physically turn off.

It can’t be pulling 6W for two power extensions with nothing plugged into them.

On a side note I’m amazed at how little the fridge freezer uses.

Do those power strips have the old-school bulbs in them, to indicate they are powered? Those took a lot of power for what they did - easily possible to pull 3W each.

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I know one does have a small led bulb to show it’s on, I’ll have to check the other. Bit of a mission to now get at the sockets with a cupboard in front :person_facepalming:

Looking at the main bedroom the ceiling had a rose centre and looks like a side light on one wall but was covered/removed. Would be sketchy if that was the reason.

I’m just thinking if it does have an IME a TV aerial amplifier as mentioned that it might be plugged in the loft? I’ll have to get the ladder out the garage.

Generally, the cables which fed lights which have been removed are terminated properly. And if not properly terminated, 2 things happen - they’ll short to earth or will pull so much current instantly that the RCD or the circuit fuse will trip, or they’ll remain open circuit. But they won’t pull a small amount of current constantly.

There’s something else behind this - and it’ll be in the loft. Ladder time! Tell someone you’re going up there and ensure you have plenty of light.

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Any fans, or sensors or that.
What about an electric shower, or pumps for water drainage from a shower that’s below the drainage outlet etc.

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No fans/sensors upstairs.

We do have an electric shower but it’s on its own breaker

Wired smoke / carbon monoxide detectors?

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Nope all battery powered :+1:

Aerial booster in the loft?

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Or in wardrobe lights

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It’s a mystery so far!

I think we’ve eliminated the common devices which may be connected to the upstairs lighting circuit, other than mains-powered alarm devices (unlikely), so it’s a trip up there to have a look. The TV amp suggestion is the most likely.

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Yeah I’m going to have to check the attic next. I’ll report back when I get a chance to get organised.

Thanks for all the suggestions

I’m curious to know how the house alarm gets power.

well, 10W is in the right ballpark for an idling alarm system, so it’s possible.

Where is the main controler box? Not necessarily the controls, they can be remote. If it’s in a bedroom upstairs, or in the attic, then it’s a strong contender, since it could easily have been wired into the lighting circuit.

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It’s going to be in the attic as it’s not in the rest of the house.

I had have a quick Google on forums earlier and it was saying it’s not uncommon to go into the upstairs lights to power it.