If you're a Tree Surgeon working on a utilities contracts, working in and around power lines isn't new...if you're more on the domestic side, we wanted to outline the main safety rules for you so you know what's going on when you're on site.
What you need to know
Contact with overhead power lines (OHPLs) causes fatal or severe electric shock and burn injuries. This can also happen when a person or object is close enough to a line for a flashover to occur. So let's take it seriously!
Striking underground cables often leads to burn injuries from the resulting explosion. It may also result in electric shock if contact is made with live conductors.
If you need to work near them, get advice from the owner of the lines, usually the Network Operator (NO).
What you need to do
When arboricultural (aerial and ground) works are proposed within 10m (measured at ground level horizontally from below the nearest wire) of overhead power lines a risk based approach needs to be adopted. In practice this means that you should seek specialist advice and guidance from the owner of the power line (Network Operator) before undertaking any work within this distance.
You must also consider:
work that is more than 10m from an OHPL but has the potential to breach it. Breaches could be caused by falling trees, timber and debris, or the use of MEWPs and cranes that in the event of collapse could fall within 10m of the power lines
the presence and the risks from underground electrical cables and other utilities.
When you need to work near OHPLs, you need to agree with the owner of the line, usually the network operator (NO) for the power lines to be disconnected.
Remember to consider the risks from, and to, all overhead and underground utilities not just electricity
The power line owner (Network Operator) should assist in establishing a safe system of work. This could include:
arranging for the electricity to be switched off
refining safety distances (depending on the nature of work, methods and contractor competency) or
arranging for works to be undertaken by a specialised utility arboricultural contractor.
The first choice when managing the risks from electricity should be to undertake the works dead. ORGANISE A POWER SHUT DOWN.
Any decision to undertake live works must be justified, documented and all that stuff.. it's a tough one to justify.
You can minimise the risk of injury associated with any task with a work plan based on:
Risk assessment
Using competent staff
Providing suitable equipment
Applying safe work procedures.
To ensure that any tree work which has to be carried out near to live electrical equipment is done safely, only work:
As recommended by the Network Operator
According to the appropriate working procedures set up by the Network Operator using appropriately qualified and competent people
Carefully plan:
The worksite
Access routes in the worksite
Tree-felling/pruning operations
Timber extraction
It's all stuff you've heard before. But it's worth doing it properly as there are too many injuries every year from Tree Workers being around Power lines - so take the time to properly assess the situation and talk to the NO.
Working from a MEWP (Mobile Elevated Work Platform) or AWP (Aerial Work Platform.
IPAF recommends two specific safe distances through its training programs:
— 50ft (15m) + fully extended boom from electrical pylon
— 30ft (9m) + fully extended boom from cables on wooden poles
Note: These safe distances meet and exceed those specified in ANSI standards and OSHA requirements. Should the operator need to work any closer to power lines, seek expert advice (contact the power supplier) and implement extra safety precautions to ensure that the MAD is never compromised
When working near overhead cables: — The MAD (Minimum Approach Distance) should be clearly marked on the ground, allowing for maximum boom outreach. — Ensure extra supervision is provided and emergency plans are in place.
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