I don't know of any spells exactly, but there are many gemstones and crystals with electromagnetic blocking/cancelling properties. Some of these include amazonite, black tourmaline, hematite, and smokey quartz. I am sure there are many others as well. These stones can be worn as a pouch around your neck, or they can be set up around electronic devices to help absorb the energy.
I did a quick Google search... and while i knew of the sun and lighting being sources... i did not realize about the appliances. Never thought about it, I wear a hematite ring all the time. with all of the appliances at home... I see why you wanted a spell.