Jeff Young, you are correct. I was subsequently told that in the 70's the code allowed such an installation. Question is now, what to do? Does this really constitute a clear and present danger? As mentioned in the original post, this gas line runs 75' to a pool heater and happens to run adjacent to where we want to install the new generator. My options as I see them are to tee off the iron pipe riser at the meter above the PVC for the generator and not touch the PVC (expensive, difficult and not elegant but not impossible) , tee off the existing PVC near the new generator using a standard PVC tee and transition to coated iron pipe (it is only about 8' -- easiest and least expensive), or replace the entire 75' run of pvc that is otherwise in apparent usable condition (prohibitively expensive.) I had two plumbers bid and look at it. One wouldn't touch it at all and said it was never legal regardless of how the pipe is marked (he was wrong). The second said yea, it was ok back in the day but not now. He suggested replacing the rusted riser to a new coated pipe using the existing PVC fitting, and then find a way to have a new gas line run to the generator, not disturbing the PVC. He did say he felt we could safely tee off the PVC (the analogy was tying in new romex to old knob and tube wiring) but also said it would probably not pass inspection and may trigger a call to replace the entire 75' -- we would roll the dice. I get it, in today's thinking, PVC should not be used for gas and in a perfect world, i'd probably replace the entire length of PVC. However the problem is that it runs under considerable concrete around the pool so replacing it in its entirety would be prohibitively expensive and arguably ugly. Like my old house, it had knob and tube wiring but the wires were in great shape and every electrician that did work said that there was really no reason to replace it just because it isn't compliant with code today.
