The Elizabeth Tower and the Great Clock are currently being completely renovated. Although the clock will only be out of action for two years, the bells have to be silenced for the entire renovation period to protect the workers’ hearing.
The Big Ben bell weighs 13.76 tonnes and chimes at 118 decibels. At that volume, people would suffer hearing damage after just 14 seconds of exposure. To stop the bells, the weights that drive the mechanism have to be lowered to the bottom of the tower and secured. This process takes half a day to do, so it isn’t practical to restart them after each workday. But the chimes will be re-enabled for New Year’s Eve and Remembrance Sunday.