What value

[Farmelectrics]

Ok so we no that for are insulation resistance tests 1 M ohm is the acceptable value well greater than that is but how do work out say for a 6 amp b type breaker how low would your reading have to go before it takes the breaker out

 

[Octopus]

Not sure what you are getting at!!

 

[Farmelectrics]

How low would your ir test have to be before the protective device tripped

 

[Silly Sausage]

Look at the Time/Current curve and work it out.

 

[kingeri]

How long is a piece of string?

 

[Marvo]

I'm a bit confused by the question, a 6A B-Curve breaker isn't a very good detector of leakage current from an IR fault.

R=V/I so to achieve 6A of leakage your insulation value would need to be 38.3ohms (38million M ohms)

 

[ArseyDee]

I stopped reading after "ok so we no that for are"

 

[Farmelectrics]

How did you pass any exams then if you couldn't read question not the best question must admit but still a question I gather you have no idea

 

[Marvo]

The question is kinda strange because an MCB isn't generally considered or specified as a device that protects against 'leakage current' caused by poor insulation.

 

[Octopus]

How did you pass any exams then if you couldn't read question not the best question must admit but still a question I gather you have no idea

I've re-read the question and I still don't know what you are asking!!

 

[Farmelectrics]

I no it's a bit strange Marco was just playing on my mind today had a lighting circuit that was 2 M ohm and got me thinking how low a reading it would take to take breaker out lol

 

[Farmelectrics]

Murdoch if you have a short it will show zero on your tester if your insulation is poor or damaged it might show for example 0.4M ohm which is not acceptable but how low would the reading need to go to disconnect your protective device

 

[Octopus]

murdoch if you have a short it will show zero on your tester if your insulation is poor or damaged it might show for example 0.4m ohm which is not acceptable but how low would the reading need to go to disconnect your protective device

l-n?
L-e?
N-e?

 

[Farmelectrics]

We'll let's say live to earth

 

[Marvo]

I gave you the resistance you'd require to trip a 6A MCB with an insulation fault but your mega tester would just say 0.000Mohms because it won't measure an IR that low.