Extreme heat and record demand caused a high number of faults across the Victorian power grid this week including in Wangaratta according to AusNet.

It began on Tuesday when peak demand was 10 per cent higher than the previously recorded peak according to an AusNet spokesperson.

"That puts significant strain on the network and at the peak we had 55,000 customers off power at 10pm Tuesday night," they said.

"We have had crews working all night and today, with damage to substations, cables, blown fuses, due to the heat.

"We've had close to 300 fuse trips, which accounts for a significant number of the outages."

Just under 5000 households were off supply, from just over 100 incidents on Wednesday with AusNet anticipating to have the bulk of customers back on power by 9pm.

There were more household blackouts in Wangaratta on Wednesday night including in the West End when two separate faults occurred on the low voltage network serving Bronmar Street and nearby streets.

Both were caused by blown LV fuses, usually triggered by extreme heat and demand, according to the Ausnet spokesperson.

The first outage (3:56pm–5:33pm) was caused when a single fuse blew, likely due to hot weather, interrupting supply to 53 customers.

The fuse was replaced and power restored.

The second outage (6:03pm–12:18am) was caused when two LV fuses blew, including the newly replaced fuse from earlier - causing a larger outage affecting 161 customers until shortly after midnight.

Field crews replaced the damaged fuses and carried out safety checks before all customers were restored.