BT has been fined £600,000 after two workers fell off ladders on the same day - with the second accident occurring when a man went to finish the job of his injured colleague.

The men were left with life-changing injuries after the incidents at BT’s Darlington Automatic Telephone Exchange.

It is believed both men fell after suffering an electric shock.

Teesside Crown Court heard how a BT Open Reach engineer was installing a cable through a hole on the first floor of the building in Barnard Street in April 1, 2010.

In order to carry out this work he was working on a stepladder amongst the lighting system.

He felt a pain in his right arm and fell from the step ladder.

He was taken to hospital with head and back injuries.

The accident was not properly investigated and later that day the work was allowed to continue.

The second engineer began working from a different ladder.

However, he too fell to the ground and was taken to hospital with serious skull and back injuries.

A year after the accident, the first engineer returned to work for BT, but he had lost his sense of smell and taste and required physiotherapy for several years.

The second engineer received serious multiple fractures of the skull and spine, his sense of smell and taste was affected, he was blinded in one eye, and has long term memory problems.

An investigation by the Health and Safety Executive (HSE) found that the work had not been properly assessed or planned.

Serious failings were also found within the electrical lighting system in that area, where workers were exposed to live metal parts, some at 240v.

The system was poorly constructed and had not been properly maintained or tested.

The court heard it was most likely that both engineers received electric shocks which threw them from the ladders.

BT pleaded guilty to health and safety breaches and was fined £600,000 and ordered to pay costs of £60,000.

HSE inspector Laura Lyons said after the hearing: “These life changing incidents could have been avoided if BT had provided safe systems of work and ensured that the electrical systems were properly constructed, maintained and tested.”

BT said it deeply regretted the incident and we apologise wholeheartedly to the people involved.

“The safety of the public and BT people is always our primary concern and, whilst we have a strong track record in that area, we have learned lessons from this unfortunate event.

“We reviewed our electricity testing procedures immediately and new procedures have been in place since 2010 to make sure this doesn’t happen again.”