Occasional "noise" on the home electrical lines will cause clocks to run at half the normal speed. Here's a weird one.. putting it out there in case it helps someone else.. We recently had a few power cuts. Oven / Hob / Appliance Clock Losing Time / Running Slow 19-02-18, 02:54 PM. If this occurs at your home: Disconnect power to the range; Wait 10 minutes; Turn the power back on; This should reset the clock and resolve the issue. About one hr per five hrs. Digital alarm clocks and those on microwaves and ovens are running slow all over Europe and the reason why is to do with a power dispute in Serbia Post by Miro » Sat Oct 10, 2015 4:58 pm Which is why things like my PC, TV & HiFi are always turned off at the mains when not in use. Correcting a Slow Oven Clock. Re: Microwave clock running slow - solved! The Clock runs for somewhere between 8-12 hours correctly then goes haywire either fast or slows down. When the power came back, we found that the oven built in clock (Neff) was running slow, losing time through the day. After a power outage, my GE Profile gas range clock runs fast.