r1+r2 values

[James Sutton]

Can any please help and tell me what is really an acceptable value for r1+r2

Thanks

 

[Dic Penderyn]

When you say acceptable! For any R1 + R2 results to become acceptable one must consider the resistivity of cross-sectional area the conductor material and its length per meter if you look at GN3 you'll find tables that have calculated conduct length per meter which should help you to arrive at an answer.

There are other factors to consider like ambient and conductor temp etc.. however as a rule of thumb GN3 IS A GOOD STARTING POINT.