Neighbour trips my RCD?

[securespark]

That's bad news. The corollary is that something they do could blow the fuse and leave her with no electricity.

Are you sure that the cable loops next door after the fuse, and that it's not like this?

//www.diynot.com/diy/threads/odd-incoming-mains-wiring.7468/#post-35074

 

[ban-all-sheds]

Fairy nuff.

 

[gavski34]

//www.diynot.com/diy/threads/odd-incoming-mains-wiring.7468/#post-35074

My house has an independant supply

 

[bernardgreen]

My house has an independant supply

Is the supply cable underground or over head ?.

It was common in the 1950's to use a single service cable from the street cable to pairs of semi-detached houses.

 

[gavski34]

Underground, comes up into the kitchen cupboard to a fairly modern looking consumer unit.

 

[securespark]

My house has an independant supply

I know. I was posting that link to show that some supplies are wired up to subsequent properties on the fused side of the service head.

 

[ban-all-sheds]

Whether the fuse is shared or not, the neutral will always be.

 

[PBC_1966]

Unless you're remote from other users and have a transformer all to yourself, there will always some part of the neutral in the distribution network which is shared.

 

[ericmark]

Shared Neutral impedance along the service cable that was probably installed to serve houses with little if any use of power other than for lighting and hence has a small cross sectional area and and higher than normal impedance. Hence the high starting current of a motor in one house will "bounce" the neutral to both houses. If one house has a neutral to ground fault then the bounce on the incoming Neutral will create a fault current along the neutral through the RCD sensor to the fault and to ground.

bounce = when the Neutral at the house is raised to a potential higher than ground potential due to abnormally high current flowing along the neutral.

I see your point, same as tripping when kettle is used but fault is with toaster. However a lawn mower is hardly a heavy current user so it is unlikely. I know the RCD should not be tripped by spikes, but I know from bitter experience they are. Since the lawn mower may have a AC/DC motor with carbon brushes which can arc there is a good chance it is spikes on the line.

If one could simply fit any din rail RCD in any din rail consumer unit then one could select a better RCD for EMC rejection. However the type testing rather limits ones options.

 

[PBC_1966]

Be grateful that the AFCI hasn't yet appeared there!

 

[Doggit]

Have you spoken to him about it; can you get him to try another mower, and see if it still happens.

 

[ban-all-sheds]

Unless you're remote from other users and have a transformer all to yourself, there will always some part of the neutral in the distribution network which is shared.

Indeed.

The point I was making was that all the talk and speculation about looped supplies, be they after a fuse or before, is irrelevant.

As is the OP's observation that his house has an independant (sic) supply.

 

[bernardgreen]

However a lawn mower is hardly a heavy current user so it is unlikely

As with all motors the starting current is high and if the switch is worn and a bit intermittant when closing there could be a series of pulses of high current before the motor gets up to speed. There would be even even longer period of high current if the blades are dragging through grass while the motor is accelerating to speed.

If there is a section of shared Neutral and that section of cable is concentric with spiral laid Neutral then there is a significant inductance in the Neutral due to the coil formed by spiral lay of the Neutral conductor

 

[stillp]

a lawn mower is hardly a heavy current user so it is unlikely

2 kW is not uncommon Eric.

 

[securespark]

Be grateful that the AFCI hasn't yet appeared there!

For the benefit of those not in the know:
https://en.wikipedia.org/wiki/Arc-fault_circuit_interrupter