Switching sound from consumer unit

[Paul Mac]

Hi, I have a MK sentry unit approx 15 years old. Occasionally I hear a sound like a mcb tripping but none has. The sound is a single switching noise as you would hear if you switched off a mcb or the rcd.
There's no buzzing or other sounds. No obvious faults, no overheating. No signs of arcing or burning. The frequency would be about once every couple of days.
I've isolated circuits leaving all but one off but can't pin it down.
It tends to happen if a couple of appliances are on such as the gas heating pump & a dehumidifier on different circuits but any combination of applicants is way below the circuit load.
I've had an electrician out to check it and he couldn't find a fault.
Could a mcb be partially tripping but not enough to switch off?

 

[Lectrician]

There isn't a contactor in or near the consumer unit?

 

[ban-all-sheds]

Is there a CU on the other side of the wall - next door house?

 

[GarethW]

Have you got solar panels ?

 

[JohnD]

I hear a sound like a mcb tripping

you mean a very soft tick?

post some photos, including the meter and any nearby equipment and cables

 

[Paul Mac]

Hi, thanks for the replies. There's no contactor in the unit, the house is small & detached. It's on an outside wall.

No solar panels fitted thanks.

It just seems a mystery. It's exactly the same noise as a breaker tripping or a light switch going on or off.

I've ruled out as much environmental things I can think of. There's nothing unusual in the attic above it. I've checked all electrical sockets & light fitting in the house.

I guess the next step could be swapping out the breakers.

 

[sparkwright]

Could it be a time clock switching over, maybe for an off-peak supply?

Pictures may help.

 

[Paul Mac]

Thanks for the replies. Pics below. I haven't done anything in the unit apart from checking the connections are ok. There's just one double light switch near it which operates two outside lights. I've isolated them and their circuits to rule them out. There's magnetic clips on the door the box is in & I've left the doors wide open to make sure it's not the sound of them closing.

 

[Newboy]

Sound of expansion/contraction of pipework?

Thermostat opening/closing?

 

[JohnD]

I see the wood round it and suspect expansion/contraction.

It will be slightly warmer when you are drawing heavier loads such as drier, washer, cooker.

If the timber trim can be unscrewed and lifted off, see if that makes a difference.

Very neat job BTW.

If you put your finger to the plastic casings of the breakers you will see if any are particularly warm (this need not be a problem, unless there is a loose connection)

Occasionally you get movement due to magnetic effects when a heavy load is turned on and off, but this would be unusual in an ordinary house.

 

[flameport]

Where is the meter, and what type is it?

 

[ban-all-sheds]

You've got arc lights in the loft?

 

[Paul Mac]

Arc lights - sadly not as ambitions LOL! The previous owner was enthusiastic with descriptions. It's just tubes up there but I'm getting ideas now!

 

[333rocky333]

I guess the next step could be swapping out the breakers.

Them breakers are now obsolete so unlikely to get new ones. sometimes they make a noise when on the verge of tripping, though If its happened several times i am sure it would have tripped at least once by now

Is it just me or is the CU configured wrong, its a split load board with a single Rcd main switch

 

[Paul Mac]

Thanks Folks. I think the wood expanding & contracting maybe the answer. It happens more frequently in winter but perhaps just a couple of times a day.

I'd thought of the heating pipes, radiators, the PVC door expanding/contracting & the plastic guttering outside.

I'll remove the box as JohnD suggests & see how it goes.

Thanks !!