Mike, Interesting point. Plumbers and Electricians use solder with entirely different specifications. For electrical wiring work, it's the eutectic alloy of lead and tin, 60-40, which has the lowest melting point, c. 200C. This reduces heat damage to components, & it sets solid without a tertiary stage. For plumbing, the alloy chosen was 70-30 or even 50-50, which goes though a 'pasty stage' like soft putty, for wiping joints. I can see the point in replacing plumbers' solder because of the lead poisoning risk. This only occurs in soft water, hard water is not a problem, but with the growth in water-softeners....
Since joint-wiping is now mostly antiquated, using a cu-sn-al-? alloy is not really a problem. In fact, a lead-tin capilliary joint forms a copper/lead/tin alloy in the thin solder film, which is why they are strong but a bugger to take apart later! As to electrical work, I can't see how the eutectic can be displaced by a trick alloy without introducing other toxic metals, or frying components with higher temperatures. What really got up my hooter in the UK was some idiot deciding that 'boss white' was dangerous for potable water joints made with hemp/oakum. It's only ground chalk and linseed oil! The green muck that replaced it had all the attributes of boss white bar one-the bloody joints all leaked!
Alan
