Where to find ERNI REL14-A2 1.3 equivalent?
Finding an exact FIT may be difficult, maybe impossible,but matching FORM (SPDT) and FUNCTION 12Vdc coil , contacts >=4A, 240Vac is easy.

IF FORM FIT and FUNCTION cannot be found, with modifications, it is possible.

http://www.digikey.com/product-detail/en/omron-electronics-inc-emc-div/G5LA-14-CF-DC12/Z2576-ND/1210594