Mains pickup

[curious67]

Can disconnectted ring circuits pick up mains at a high enough level so that you can measure say 10V ac between the disconnected live and N. Also can momentarly connecting the disconected live to N or earth cause an RCDs to trip? Thanks

 

[timtheenchanter]

I had a similar problem, check this post
http://www.diynot.com/forums/viewtopic.php?t=40505[url][/url]

 

[plugwash]

Can disconnectted ring circuits pick up mains at a high enough level so that you can measure say 10V ac between the disconnected live and N.

if using a high impedance meter then yes indeed you can get much higher readings than that. However they should drop away at the slightest hint of a load.

Also can momentarly connecting the disconected live to N or earth cause an RCDs to trip? Thanks

no but connecting the still connected neutral and earth to each other through a low resistance object (e.g. a knife blade) is almost gauranteed to take out a RCD!

 

[ebee]

If you`re getting a voltage it could be from inductance or capacitance. But you`re RCD question makes me think also about insulation resistance.
Are you sure you`re N is properly disconnected completely?
As our friend said - the smallest load should dimish it significantly.

 

[Lectrician]

With appliances plugged in, shorting L to E will trip the rcd with the live dead(or alive).

Shorting N to L will not cause the rcd to operate. It may if you have the circuit off, and the insulation resistance isn't good (in circuit or appliance).

What are you actually doing.

 

[curious67]

I'm was using a high impedance multi meter (hence the volts) and of course a momentary N to E short will modify other connected ring ctt flow & hence trip the RCD. I was adding a spur to a ring. I just wanted to have an explanation for the symptoms. Thanks