another calculation qusetion

[linnsound]

can this be done...i have a fault on a ring below floor and am trying to find which floorboard to lift up and was thinking that if i measured resistance at point A ie R1+R2 * multiplier *l/1000, and then at point B, would subtracting the first value form the second hint roughly at where the fault lay. Or does anyone have a better way of calculating this.?.trying to use my head here...ouch

 

[nozspark]

Ah,,,,

But using this method you are assuming where the cables run. In houses you can find some weird and wonderful routing

 

[ColJack]

you don't specify what "fault" you have.. so it's hard to suggest ways of finding it..

 

[RF Lighting]

Also, this method will only work it the fault is a proper dead short. If for example a cable has been nailed through then this often creates a high resistance fault which could throw you well off the scent.

 

[Spark123]

I don't follow why you subtract the point B from point A, if in an ideal world the conductor temp is 20ºC and it was a dead short, taking the resistance of phase-CPC from either point and dividing it by the ohms per meter value @ 20ºC for a 2.5 with 1.5mm CPC cable will, in theory at least, reveal the distance from that point to the fault.

Note, the tabulated values in OSG are in mOhms/m @ 20ºC, divide this figure by 1000 to give Ohms/m.