Snubber Capacitor for a AC coil - contactor

[golash]

HI

I am reworking my control box of my DIY 3 axis cnc. In various forums I see there can be a problem
with a contactor emitting emi from the coil. My coil is a AC type. I located this Cornell Dubilier Suppression
504M02QA100 0.5 UF 100 OHM Snubber Capacitor 200v
Its mentioned that the snubber is in parallel with the coil connections. Is this correct.
Does this snubber have the correct specs for my contactor.

Thanks for your help!

[Kjelt]

AFAIK a snubber is used across the (switching) contacts to suppress arcing, not the coil.
Edit: in the last page of this pdf it is used across the coil, for ac this would make sense, for dc a diode is always enough.
http://www.bpesolutions.com/bpemanuals/Snubber.pdf

[golash]

Hi
Here is a thread I used as reference information.  http://www.cnczone.com/forums/general-cnc-machine-related-electronics/151824-ac-dc-power-isolation.html
A person in the forum mentioned the following info: "That appears to be a RC snubber, it is intended to go across the coil terminals, not the power contacts, although there are versions that are intended to be wired across the power conductors but are usually larger capacity."
I`m uncertain as to what`s correct.

[SeanB]

Across the coil it is better to use a MOV of appropriate voltage rating, which will clamp any high voltage spikes to a safer level. The RC snubber will also work, but the MOV does a better voltage. Typically if your coil is a 24VAC one the MOV will be a unit between 24 and 30VAC rated.

[Seekonk]

I actually used to manufacture snubbers.  Use it across the coil.  RC will be quieter than a MOV.  Most MOVs will allow excessively high voltages. 

[golash]

Hi Seekonk
Do the specs on the snubber seem correct for my setup. The contactor has a AC coil and the total system current is 20 amps.