Post-transition metal packing structure. Tin forms Zintl phases such as NaSn, BaSn, KSn and CaSn. It has good corrosion resistance in air on account of forming a thin protective oxide layer. Pure tin has no structural uses. It is used in lead-free solders, and as a hardening agent in alloys of other metals, such as copper, lead, titanium and zinc. Lead is a soft metal (MH 1.5, but hardens close to melting) which, in many cases, is unable to support its own weight. It has a close-packed structure (BCN 12) but an abnormally large inter-atomic distance that has been attributed to partial
Electrical wiring circuit protection, an isolated-phase bus is used. Each phase of the circuit is run in a separate grounded metal enclosure. The only fault possible is a phase-to-ground fault, since the enclosures are separated. This type of bus can be rated up to 50,000 amperes and up to hundreds of kilovolts (during normal service, not just for faults), but is not used for building wiring in the conventional sense. Electrical panels are easily accessible junction boxes used to reroute and switch electrical services. The term is often used to refer to circuit breaker panels or fuseboxes. Local codes can specify physical