Composite covers insulate – Iron covers conduct!
In June this year 15 year old Anna Lambden was walking with a friend in Sydney when she stepped on a metal manhole cover and received an electric shock that nearly killed her. Anna’s friend and a bystander that came to her rescue also received shocks. Anna was hospitalised and almost four months later she continues to be affected by her injuries as a result of the electrocution. It turns out two other people had reported being electrocuted in this location only a week earlier.
In the USA Jodie Lane, a doctoral student, was out walking her dogs when she stepped on a metal manhole cover and was electrocuted. Jodie died as a result of the electric shock she received. The local Utility company responsible for the manhole investigated and found a further 280 pit lids in surrounding areas with stray current passing through them – some at potentially fatal levels. They had to extend their review to test a further 550,000 pits for energised lids. The Utility settled on a USD $6.5 million payout to the family and has set up a USD $1 million scholarship fund in Jodie’s name along with implementing a stringent safety review. Unfortunately these electrocutions didn’t come as a complete surprise to anyone!
This isn’t a new problem.
There had been plenty of reports of problems with stray current passing into metal covers. In New York many dogs, including a police dog, have been electrocuted when stepping onto energised metal pit lids and several people have also suffered burns. Some dog walking associations send out annual winter reminders to keep dogs away from metal lids and poles. Dogs are particularly at risk as they don’t wear shoes that offer us humans some protection from the receiving a shock. Similar incidents have been reported in Canada and elsewhere.
So what exactly is going on?
The risk of electrocution occurs when metal manhole covers exist in combination with charged wires (usually related to traffic signals or tramways) and water – think rain. These at-risk covers are ‘insulated’ from the surrounding earth by concrete or other materials which may allow for electrification. Wiring can be either in the pit or nearby – that means it’s not always easy to identify which lids are likely to be dangerous. The simple answer is that all wet, conductive metal lids are potentially dangerous.
Non-conductive manhole covers solve the problem.
To eliminate the problem entirely, manhole covers should be non-conductive. Terra Firma BR60 fibreglass composite Traffic Signal covers offer the perfect solution. Strong, lightweight and lockable these non-conductive composite pit lids are the perfect alternative to risky metal covers. If you want to know more about Terra Firma’s non-conductive Traffic Signal covers download the Terra Firma BR60 Brochure now . To learn more about Terra Firma composite access covers speak to one of our expert technical team on 03 9357 1230.