Burnt electrical cord and cord end at fish farm site

Location: Port Hardy

Regulated industry sector: Electrical - Low voltage electrical system (30V to 750V)

Impact

Injury

Qty injuries: 0

Injury description: NA

Injury rating: None

Damage

Damage description: 20A 250V cord end burnt and melted away

Damage rating: Minor

Incident rating: Minor

Incident overview

On December 23, 2019 workers returning to a remote fish farm site saw pen number eights netting smouldering. They found a burnt electrical cord and cord end, that had been supplying power to the pens underwater camera. The site had been vacant for approximately five days due to storm conditions; therefore the actual time of the incident is unknown.

Investigation Conclusions

Site, system and components

Each fish pen has a camera winch assembly. The assembly is supplied with 208V off a 2-P 15A breaker. Between the 120/208V panel and the assembly is a plug box.

Flexible #12/3 copper SOOW cord is used between the panel and the assembly allowing the cords to be unplugged and stored when not in use. The cord ends in the plug box are 20A 250V twist lock. The cord ends at the assembly are 20A 250V of the plastic pin and sleeve type and rated for use in wet locations. The cord ends have a cap that closes when not plugged into the camera assembly. The assembly has the ability to lower the camera under water while keeping the power connection above the water line.

Failure scenario(s)

The #12/3 power cord to pen #8 was unplugged from the camera assembly, but still plugged into the plug box and energized. Fish harvesting was in process at pen #8, but unable to be completed due to storm conditions. The pens plastic netting was bunched up around the cord end. The energized cord ends terminations were likely in poor repair deteriorating further under storm conditions. The cord end overheated melting itself and the netting. The breaker eventually tripped. After five days away due to the storm workers returned to find pen 8 smouldering at the location of the cord end.

Facts and evidence

Electrical FSR interview:

· Workers told the FSR they found pen #8 smouldering upon return to work

· FSR found the cord end to pen 8 burnt away.

· FSR found seven similar #12/3 SOOW cords for other pens were on a skid in the storage shed. They were wet and some had a brown/yellow liquid drain out when he opened the cord end caps

· FSR found one of the cords was pulled from away from the cord end exposing conductors

· FSR said the 2-pole breaker was tripped

Safety Officer observation of photos provided by FSR:

· Cord end was pulled away from cord exposing conductors on similar stored cord.

· Multiple discoloured wet cord ends on similar stored cords.

· Cord end burnt away on affected cord.

Causes and contributing factors

The cause of this incident was likely due to a poor electrical connection. The cord to pen #8 was left out in the elements energized. There were 7 similar cords stored under cover; and they were in disrepair, with wet discolored cord ends. It is probable that the burnt cord to pen #8 was in a similar state of disrepair. The cords electrical terminations if already in poor condition would be subject to further deterioration when left out during the 5 days of stormy conditions. It is likely a failure in the insulation between conductors in the cord end heated, melting the cord end and plastic netting it was in contact with before the breaker tripped.

 

Approved camera assembly

 

Camera assembly pin and sleeve connection

 

20A 250V pin and sleeve cord end wet and discolored

 

20A 250V cord end melted away

 

Cord pulled away from cord end