Over 750 homes in Grimsby without power following open PEN fault

More than 750 homes across Grimsby have been left without power following a widespread outage across the town.

People reported the incident in the early hours of Wednesday, March 22, with residents out on the streets in their pyjamas as they tried to establish what was going on. One resident said: "It’s carnage. The power started pulsing. Them lights began popping and TVs were smoking. Anyone who put a light on had a sudden explosion. It’s a mess - everyone’s electrical appliances are blown."

Nothern Powergrid updatetd the situation to say:

The fault occurred at 02:40 on 22 March 2023 and impacted homes across 20 streets in Grimsby. The fault caused irregular voltages in customer homes, which meant that up to 415 Volts, rather than the typical 240 Volts, was supplied to power outlets causing damage to internal electrics and appliances. All customers were reconnected to the network within the day but, in some cases, repairs are required in customer’s homes.

The voltage changes occur due to a shift in the ratio of balance of load in the network. You see when Neutral is lost then the centre point (or star point) which is commonly refenced as 0 V will now 'shift' until a balance point is reached elliminating the need for a neutral current - at this point the star point is said to be floating to a position of balance.

This is illustrated on the phasor diagram below. The distance from the centre point of the triangle to the displaced star point of the three-phases indicates the touch voltage to Earth; 64 V. The star point having moved towards the heaviest loaded phase, in this case, L3.

Andy Bilclough, Northern Powergrid’s Operations Director said, “Neutral faults occur infrequently but we understand that they can be alarming to those affected when they do occur. However, our teams were onsite quickly to support our customers and we are working alongside our partner (GES) to repair or replace what has been damaged. For our customers whose boilers were affected, we have either sought to repair the boiler or provided temporary heating arrangements.”

Reports online show that some homes have lost heating and the damage to electrical equipment in peoples homes has reached up to £10,000.

“Some people have lost everything. One neighbour came home from holiday yesterday to find his television, washing machine and cooker all wrecked.

“This is going to cost Northern Powergrid a fortune.

“There were engineers all over the place through the day and one of them told me that it must have been a hell of a surge.”

In total 760 homes were affected in the west of the town.

Another resident said: “We noticed something was up in the early hours when the street lights got brighter and brighter.

“Then they started smoking and they popped like bombs going off.

“Every electrical item in our homes has been blown to bits - the house alarm, the telly, the boiler. They’re all knackered.

“The place is crawling with engineers and loss adjustors. I reckon I’ve had £10,000 worth of equipment wrecked.

“They’re looking at a bill of hundreds of thousands.

“This is completely unprecedented. It’s a major incident."

One of the fundamental principles of BS 7671 is protection against overvoltage, yet over recent years advice and guidance on the selection and installation of surge protection devices (SPDs) has been confusing and weak.

Training has been poor and CPS guidance has been poor. The biggest reason for this misguidance is the economical compromise form their advice to large employers and industry stakeholdeers - this means they avoid providing firm guidance which will support electricians properly.

In the case of SPDs in the domestic sector - the economical indifference between the cost of the SPD versus the likelyhood and cost of damage from overvoltages has convinced thousands of electricians to swerve away form the installation of SPDs.

Hopefully articles and information like this can allow us to evolve a little bitt more and make wiser selection decisions with the considerations of overvoltage protection moving forward.