Transpower says work is underway to determine how the cat got into the substation and caused the outage so it to stop it from happening again. Photo: RNZ / Diego Opatowski
A vet says the body of a cat killed when it caused a short at a Hawke's Bay substation knocking out electricity to 50,000 properties shows no visible signs of injury.
Candles and torchlight lit up households across Napier and Hastings on Wednesday evening when electricity cut out for about 45 minutes before 7pm.
Transpower grid delivery general manager Mark Ryall said the feline got into the "worst possible location".
It bridged terminals on the low-voltage side of a transformer, shorting it and causing an electrical flashover - or explosion - killing the animal and knocking out power.
Taradale Vet Hospital said the body of a grey female tabby with white paws and a white stripe on its nose found at the Redclyffe substation had been dropped to its clinic.
It was not microchipped, and the body would be held at the animal clinic for seven days in the hopes any owner would come forward.
Transpower believes the animal is likely a stray, given the substation's rural location.
Taradale Vet Hospital lead vet Clive Hambly said clinic staff were "shocked and amazed" when the animal that had caused the outage was brought in.
There was also surprise it had no visible signs of injury.
Hambly expected the cat to have burns or some indication it had been electrocuted but there was not any.
"There's no evidence of any burnt fur: paws, nose, ears - nothing seems to [have been] affected adversely."
It was almost difficult to believe electricity was the cause of the death, Hambly said.
A possible explanation was the cat was chasing another animal which caused the outage and it was close enough to be shocked and instantly killed - but it was impossible to know, Hambly said.
RNZ spoke to a number of electricians and electrical engineers who agreed they would have expected the animal's body to have been severely damaged by the electric shock.
They said while it was a little mysterious there were many factors at play which could account for the lack of damage. Heart failure was a likely cause of death.
A Transpower spokesperson confirmed staff took the animal to the vet hospital.
They said detailed work was being done to determine how the animal got into the substation and caused the outage so as to stop if from happening again.
There were a range of measures in place to stop situations like this, they said.
The station was operating without its usual second transformer as a backup after flood damage from Cyclone Gabrielle.
Ryall said it was very rare for animals to cause issues at the substation.