Lead-tin solder ban (1978) and Boston fire-watch regulation

Externalities of material selection. The 1978 ban shifted plumbers to 95-5 (tin-antimony) solder, which produced more leaky joints. Combined with Boston's hot-work fire-watch requirement (paid off-duty firefighter at sixty dollars/hour), this drove adoption of mechanical crimp-on copper fittings ("PEX-A" cross-linked polyethylene became dominant in new construction).

Does anyone know why we've gone from soldering pipe to using this crimp-on mechanical connector? Because too many plumbers burned down too many houses soldering pipes. The law now says, in the last ten years in Boston, you must have a fire watch. This is one of the externalities of material selection. They got rid of lead-tin solder in 1978 by legislation. So they went to 95-5 — ninety-five percent tin, five percent antimony, or some have a couple percent silver for strength.