Karl Banks

Hi Everyone I'm fitting an Access Control Panel with a MagLock, Keyboard entry etc. The manufacturers advise me that The panel can/will supply power to the Maglock without the need for an addition power supply but I'l nee to fit aMetal Oxide Varistor across the power rails in the MagLock to suppress transient Voltages. The MagLock Draws 420mA 2 12 Volts, The panels power supply provides 500mA @ 14.3 V I'm struggling with the math :(( PLEASE can someone suggest a suitable MOV and a part number/supplier? Any help would be much appreciated Banksy.