I use neither PVC enclosures or RHPs, but many here do & love them- I believe certain sources of PVC enclosures will also install the RHPs for you, & are knowledgeable about what size RHP is needed- that would be the easiest & probably best way for you to handle it. Just giving a quick (& incomplete) answer.I believe the RHPs are the preferred way to heat PVC enclosures- I'll let others give you input on who's the best to buy from. As far as I know, they've proven very safe.