IR Tests & Fault Finding

[Prime Design]

Hi fellow electricians,


I'll get straight to the point.
How low do the readings for an IR test need to be on 250V or 500V scale before a 30mA RCD or 32A MCB trips when the circuit is live and in operation and where would I find that information? I know it will trip straight away with a dead short but if I get 50M ohms for example on the dead test and then liven the circuit up is it likely to trip after a certain period of time?
Also why does the RCD or MCB not trip straight away? What factors affect the circuit to the point that the RCD or MCB decides it's time to trip if there is not a dead short and there is no faulty appliance?


Finally, can someone confirm that the best way to find the furthest point on a ring in which to split the circuit in half is the socket with the highest Zs.


All contributions are appreciated
Many thanks

 

[guest119]

I don't know who Glenn is

Stay tuned, the clock is ticking!

Boydy

 

[Knobhead]

Prime Design?

 

[DPG]

I'm intrigued. Your website offers a complete range of services including fault-finding, installations, testing, the whole 9 yards. Is this your company? Daz

 

[Resu]

Ignore this post!

 

[Resu]

Something strange going on with Tapatalk!

 

[Knobhead]

 

[Guest77]

Hi fellow electricians,


I'll get straight to the point.
How low do the readings for an IR test need to be on 250V or 500V scale before a 30mA RCD or 32A MCB trips when the circuit is live and in operation and where would I find that information? I know it will trip straight away with a dead short but if I get 50M ohms for example on the dead test and then liven the circuit up is it likely to trip after a certain period of time?
Also why does the RCD or MCB not trip straight away? What factors affect the circuit to the point that the RCD or MCB decides it's time to trip if there is not a dead short and there is no faulty appliance?


Finally, can someone confirm that the best way to find the furthest point on a ring in which to split the circuit in half is the socket with the highest Zs.


All contributions are appreciated
Many thanks

???? :smilielol5:

 

[Geordie Spark]

I'm intrigued. Your website offers a complete range of services including fault-finding, installations, testing, the whole 9 yards. Is this your company? Daz

It's his company but we are the Fault Finding division of it.

 

[trev]

Well done Fatha, you get today's award for ancient thread resurrection

 

[telectrix]

Holy resurrection batman.

 

[telectrix]

BEATEN TO IT BY TREV. :ack2:

 

[marc8]

0.26 is normally a neon & 0.23 can be electronic piece of equipment still on the circuit, so if you get a low reading around this point always worth having a further look to see if everything is unplugged.

 

[Geordie Spark]

Well done Fatha, you get today's award for ancient thread resurrection

Thanks Son!

I was wondering who would be the first to spot it and am delighted that it was you!! :hurray:

 

[ipf]

Holy resurrection batman.

I thought we had to wait 'till tommorow for that!!!

 

[Geordie Spark]

I thought we had to wait 'till tommorow for that!!!

Here you go!! --->>> https://www.youtube.com/watch?v=B7I9zAUuiGQ

NOT the best recording but it's all I could find.

Sorry about that.