Thousands of businesses and homes in the northeast of Sydney’s CBD spent a day or more without telephones and the internet yesterday following a "little incident" with a trench digger. It’ll take a week and $1 million to fix the damage -- let alone what it cost in business downtime. How can you avoid problems if something similar happens in your street? So what happened, exactly? Around 9.30pm Tuesday night Subakette, a contractor for EnergyAustralia, was digging some "trial holes" near the corner of York and Erskine Streets. It’s part of a cable upgrade associated with a new electricity substation, in turn part of improvements to avoid the blackouts experienced earlier this year. Telstra cable ducts, encased in solid concrete, lie just 400mm below the surface. They can’t be deeper because it’s above the underground CityRail station at Wynyard. The digger went straight through them -- eight fibre optic cables, plus three major copper cables totalling 10,000 pairs of wire. "They’ve gone through the ducting and through the cables – some have been cut and gotten jackhammer marks all over them," says Telstra spokesperson Craig Middleton. Why is it taking so long to fix? Telstra’s had to get out their own jackhammers, dig out the damage cable, then lay new cable back to the Kent St exchange. Then it’s a matter of figuring out which services were running where and joining everything back together -- and praying your records are up to date. Optical fibre is relatively quick to splice but carries massive amounts of data, so that’s tackled first. "The eight damaged fibre optic cables have been replaced and rejoined and are now back in service," Middleton told Crikey this morning. This reconnected the 11 mobile phone towers that were knocked out, plus wholesale and some data services. Fixing copper takes longer, even though the three new cables have already been laid. "Ten thousand copper pairs to be joined at both ends of the new cable length -- one team working in a 1.5 metre deep pit about a metre wide and another working underground in a tunnel. That’s a heap of crimping," said Middleton. "Fortunately with each rejoin that’s another service back on line. Not every pair in the three cables was active so we are prioritising the 2200 active services." As of mid-morning today, they’d done around 300. Why didn’t Subakette know the cables were there? Shouldn’t they pay? That’s the million dollar question. Literally. Subakette said they did use the Dial Before You Dig service. Is that true? Did the contractor dig in the wrong spot? Was the map wrong? Investigations are under way. Subakette might end well up being liable. Even if they did look up the maps, they’re also supposed to visually expose the underground pipes and cables manually before starting the heavy machinery. Could it happen to me and my business? Yes. Cables are cables, and cables can be cut. Even with mobile broadband, someone could cut the cables leading to the cell towers. But my business needs the phone and the internet! I can’t be offline for days! Well, you’d better have a contingency plan! How about mobile broadband with a different carrier for an alternative internet link, plus a documented, tested procedure for switching over in an emergency? How about splitting your office over two locations, so any outage only affects half your business? How about published alternative phone numbers? Whatever you decide, you’ll need to have it sorted out in advance. That sounds expensive! More expensive than having your business offline for days and your staff paid to twiddle their thumbs? That’s the risk analysis you need to make, and any decent IT or communications services company can help you with that. View our Crikey Clarifier archive