ring final continuity

[buttonmoon]

While testing R1+R2 2.5/1.5 T&E on a 3 bed house Line and Neutral crossed over on opposite legs I recorded .34 ohms on all bar one of the sockets which gave a reading of .49 ohms. "A Spur!" everyone says. Now when deciding what to write on my form I think it goes .49x4=R1+R2 or would it be (.34x4)+(.49-.34)=R1+R2 Due to the fact that the spur is more akin to a radial? Results respectively 1.96 ohms or 1.51 ohms. Both a little high for any modern MCB and we haven't even gotten around to Ze on this TN-S system.


Any ideas chaps???

 

[GStueyXR]

Your R1+R2 is read when Line and CPC are cross connected. NOT L+N.
And then it is the highest measured reading that is recorded as R1+R2 of the circuit.

The cross connection of L+N just confirms that the L+N conductors are connected to the L+N socket tubes (but does not confim full polarity), and that there are no high resistance connections.

 

[xraytek]

While testing R1+R2 2.5/1.5 T&E on a 3 bed house Line and Neutral crossed over on opposite legs I recorded .34 ohms on all bar one of the sockets which gave a reading of .49 ohms. "A Spur!" everyone says. Now when deciding what to write on my form I think it goes .49x4=R1+R2 or would it be (.34x4)+(.49-.34)=R1+R2 Due to the fact that the spur is more akin to a radial? Results respectively 1.96 ohms or 1.51 ohms. Both a little high for any modern MCB and we haven't even gotten around to Ze on this TN-S system.


Any ideas chaps???

I dont understand how you get R1+R2 after measuring R1+RN, and I dont see why you are multplying your readings by 4.
If you measured end to end resistance then its r1+r2 divided by 4 that gives R1+R2.
But as you have cross connected the wires and then taken a measurement then what you see is the correct provided you cross connect live and earth wires

 

[buttonmoon]

Sorry I meant Line and cpc

 

[buttonmoon]

OSG p82

"The readings obtained at each of the sockets wired into the ring will be substantially the same and the value will be approximately one-quarter of the resistance of the line plus cpc loop resistances, i.e. (r1+r2)/4.

 

[Steve34]

thats little r1+r2 buddy, thats your end to end readings divided by 4, you've cross connected the L-E so the highest reading you get will be the R1+R2 you record on whatever form your doing. Steve