Strange buzzing switch fuse!

[Dave_]

Old Wylex 5419 switch fuse making a buzzing noise.

Opened it up no sign of overheating loose connection etc

Only does it sometimes...

I have seen meters, rcds, mcbs buzz but not a switch fuse...

Very strange.... any ideas?

 

[Pete999]

Overloaded circuit? any testing been done?

 

[soms]

Welcome the insight of the experienced contributors but my thought might be the possibility of a build up of dirt/corrosion on the switch contacts causing some arcing? I understand things also vibrate at resonant frequency but it would have to be something which vibrates intermittently at 50 Hz!

 

[Lucien Nunes]

Meters, MCBs, transformers etc buzz because they contain coils that produce magnetic fields; any parts that vibrate in sympathy with the magnetic field act like miniature loudspeakers. A switchfuse does not contain a coil, therefore any buzzing is likely to be from a bad contact arcing ever so slightly. It has not got hot enough to notice yet, but probably will.

 

[BOYD BARKLEY]

Old Wylex 5419 switch fuse making a buzzing noise.

Opened it up no sign of overheating loose connection etc

Only does it sometimes...

I have seen meters, rcds, mcbs buzz but not a switch fuse...

Very strange.... any ideas?

Do you know what its feeding

 

[Octopus]

Are there LED's on the circuit being dimmed?

 

[Dave_]

see if this link works to see video sent by client.....

Shared on 5 Mar 2018 - https://we.tl/s-LRtcwEfN12

There is a row of four main switch fuses with meters below supplying 4 flats in a victorian conversion.

I was told it was a main switch buzzing and I said no i'm sure its a meter and they were sure it was the switch. Video proves it is the switch (sent after I was there) I opened up all four switches when I was there and all connections are sound, no sign whatsoever of overheating, they were probably fitted in the 1980s and are absolutely mint, I don't think it's a loose connection or arcing but that seems the only plausible explanation. It supplies a one storey 1 bed flat, not sure what type of lighting.

Weird!

 

[westward10]

So it stops when you push the cover down looking at the vid? Can you feel it at all.

 

[Jim90]

Literally had this on a brand new MK metal clad sw fused spur. It was fusing down a heating system. Replaced with a new one and it was fine. Cost peanuts to replace - must be an issue with internal connections

 

[Octopus]

Love the use of technology to show us the fault.

Have you tried replacing the fuse inside?

 

[marconi]

We can see two conductors passing through an entry at the bottom of each Main Switch and I think an earth too. How are the feeds from the meter routed into each Main Switch? Do they enter each Main Switch through the same entry hole to prevent eddy currents? If they don't then this might be what is causing the mains hum.

It could also be that the line and neutral conductors have been routed inside the enclosure so as to form a coil and that their magnetic fields are adding together, and interacting with the metal enclosures.

 

[Lucien Nunes]

Are those conventional dial meter(s) below the SF's? If so, stray magnetic field from the meter may be causing the metal case of the SFs to vibrate, in particular the cover and base may be alternately attracted together and released. It may even just be faint mechanical vibration from the meter being transmitted through the backboard, causing the SF cases to resonate.

 

[Bobster]

It's not going to be eddy currents causing that noise. Otherwise it would have happened right at the time of installation.

 

[Dave_]

Didn't try changing the fuse, and the vid is from the client, so not sure how it feels, its an intermittent fault, sometimes stops when they slam the door, all the meters and SF's etc are by the front door.

I thought it may be a meter vibrating like mad thats actually making the fuse enclosure above rattle. meters are directly below switch fuses. Meters are securely fixed to board and not loose.

Feeds enter the bottom, 16mm tails and exit via SWA at the top.

Interesting answers thank you gents

 

[Octopus]

Do let us know what you find...