Editing Mercury switch (section)

==Advantages==
Mercury switches offer several advantages over other switch types:
* The contacts are enclosed, so oxidation of the contact points is impossible. 
* In [[Electrical equipment in hazardous areas|hazardous locations]], interrupting the circuit does not emit a spark that could ignite flammable gases.  
* Contacts stay clean, and even if an internal arc occurs, the contact surfaces renew on every operation, so they don't wear out. 
* Even a small drop of mercury has low resistance, so switches can carry useful amounts of current in a small size.<ref>Martin J. Heathcote, ''The J & P transformer book: a practical technology of the power transformer'' Newnes, 2007 {{ISBN|0-7506-8164-0}} p.285</ref> 
* Sensitivity of the drop to gravity provides a unique sensing function, and lends itself to simple, low-force mechanisms for manual or automatic operation. 
* The switches are quiet, as no contacts abruptly snap together. 
* The mass of the moving mercury drop provides an [[Bistability|over center]] effect to avoid [[Switch#Contact bounce|chattering]] as the switch tilts. 
* The envelope can include contacts for two or more circuits.