Can somebody explain this.

[sham]

I copied this pick from another thread, nobody can work out why this is done. So I thought I give it a go here.

 

[westward10]

They look like capacitors.

 

[rapparee]

Perhaps it is to counteract voltage collapse

 

[Octopus]

Another thread?

Another forum more like

 

[freddo]

I can't see them serving any purpose.

 

[Darkwood]

It's an attempt although flawed thinking to try stop flickering of lights or voltage drop probably from external sources, it not only would have little effect it is dangerous. I assume it was done as a joke tbh but there are idiots out there that may think this way.

 

[Lucien Nunes]

That makes zero sense. When the MCBs are closed, the capacitors are approximately shorted out. When an MCB opens, a small amount of current leaks into the circuit from another circuit via the capacitor(s). The left hand one appears to be marked 10N which I read as 10nF. Current into a dead circuit would be 230.2.pi.50.10exp-9=0.7mA. The only application I can see is to suppress a breaker opening transient due to some odd stuff being on the circuit, but then you would want the suppressors all to a common point, not from one circuit to the next. Another possibility is that something radiates RF and the circuits are acting as antennas, being mutually isolated at RF by the inductive reactance of the magnetic tripping coils. The capacitors shunt the tripping coils paralleling the circuits at RF. All a bit far fetched. I think it's generally a mistake.

They seem to be polycarbonate dielectric types (no longer available) of about 630V rating (from their size). Not being self-healing like class X and Y caps, they are not intended for mains suppression applications and could fail short-circuit and prevent an MCB disconnecting the circuit.

Hmm, there might be something to what Darkwood says about a joke. Somebody might have been trying to teach their apprentice a lesson about isolation. Put the caps in to leak a small current into a circuit, enough to give them a jolt or a funny reading but not likely to cause serious shock. The value is about right for that. But then didn't take them out afterwards. Or left it as an easter-egg for someone else.

 

[dmxtothemax]

They could also be RF links,
for data over power cables
between different phases or circuits.

 

[Wilko]

Agree with above. It is potentially dangerous and of no value that I can think of.
But for some reason it made me think of this sketch, and made me laugh, so I thank you Sham! You've given me a Capacitor and I'll raise you a Duck .

 

[Octopus]

They could also be RF links,
for data over power cables
between different phases or circuits.

That is a single phase board and powerline adaptors work between circuits on a single phase

 

[marconi]

Some FM radio receivers used the mains lead as an aerial. A very low value class Y capacitor linked the Line to the tuner or there was a capacitive pick up by wrapping the wire FM antenna from the tuner several times around the outside of the mains lead. The idea being that frequency modulation would not suffer from mains borne interference as amplitude modulation would. Maybe then, whoever owned the home with this CU went a step further and combined at FM/VHF frequencies the final circuits for the sockets and internal lighting to form a much larger aerial array (and thus pick up a stronger signal) using these 10nF capacitors and relied on the mcbs' overcurrent coils providing high reactance to isolate it from the ground plane.

At 100MHz a 10nF has a reactance of less than 1 Ohm.

 

[Barryscott]

A poor attempt at lagging p.f correction?

 

[Deleted member 26818]

A little concerned that there are two 30A breakers with only one 2.5mm2 conductors then there are two 5A breakers which appear to have two 2.5mm2 conductors in one and three 2.5mm2 conductors in the other.

 

[sparksfly]

1x 2.5mm2 on 30A MCB is fine if its a single socket outlet...unless you are thinking 1x ring over 2x MCBs