How do I tell the polarity of a DC Coil for Contactors and Starters?

There is no polarity to a DC coil if the coil is not marked with plus(+) and minus(-) markings. For DC coils with no markings,  It does not matter which way the current flows and you can connect without consideration to polarity. 

For coils that are marked with a (+)or (-) you will need to connect for polarity shown to assure coil operation