# How to evaluate equivalent insulation resistance of two cables?

My guess was that the equivalent insulation resistance of two cables in parallel is same as the equivalent resistance of two resistances in parallel. But instead it is the sum of the two insulation resistances. What is the logic behind this?

• Welcome. That is often referred by the DC breakdown voltage per mil of thickness. If you want dielectric losses at certain radio frequencies,or digital signal loss or phase-shift per meter, those are all separate issues. Please be specific about your question(s). Your wording is confusing. Two resistances in series is what you might be looking for.
– user105652
Feb 6 '19 at 1:40
• Let's play a mind game. Imagine that there is a battery connected to the parallel conductors. Now imagine how any leakage current would flow from one conductor to the other. The current has to pass through the insulation of the first conductor, then flow through the insulation of the second conductor. In other words, the insulation resistances are in series. Feb 6 '19 at 1:42
• Thanks @Dwayne Reid But how would the leakage current of one cable pass through the second cable? The leakage current flows radially outward right? Feb 6 '19 at 1:48
• I'm re-reading your question and I may have misinterpreted what you asked. Are we talking about two separate conductors that are connected to two different nodes in the circuit? Or are the conductors connected in parallel with each other? My comment is correct for the first case but not correct for the second case. Feb 6 '19 at 2:49
• The conductors connected in parallel with each other. Feb 6 '19 at 3:15