President of Awarua Communications Museum Robin McNeill said the museum which covers the history of communications in Southland and New Zealand has been closed since August 4.
"We think there was definitely a voltage surge because a whole lot of stuff died.
"It's hard to say what might have actually happened, but it does seem like there was an extra voltage down the line and into the building. It's the only credible explanation."
The incident did not affect the illumination of the building, but had damaged several important items.
It included some popular displays such as the Private Automatic Branch Exchange (PABX) display and early telephone equipment, such as party-line phones.
The projector of the replica of The Regal theatre — a private theatre that once operated in Invercargill — was also affected, he said.
"The problem is that the museum's been off the air because all our emergency lighting systems were blown up and some of the audio amplifiers aren't working because the power supplies for them are blown up.
"Some of the exhibits aren't working because they're blown up, and we've got a microwave blown up —which is pretty interesting — and a data projector blown up, and a few radios not working.
Mr McNeill believed it would cost about $10,000 to fix everything, but the museum did not have the money in the bank.
To have the doors closed was also challenging as they lost their income from patronage, he said.
"When a place operates on a shoestring, cash is always pretty important. The fact that we can't open the museum until we get it fixed is a problem."
The museum board would meet its insurance company, hoping to obtain what was needed to fix the emergency lights, which will let them reopen again.
The historical displays would be fixed by the volunteers as soon as possible.
"We got some pretty innovative volunteers who have a hobby of fixing old electronics, so we're pretty confident we can get everything fixed.
"I'm pretty hopeful that while we won't have it going this coming Sunday, we will in a fortnight's time."
The museum opens Sundays from 1pm-4pm.
