Safety Bulletins: LV Flashover and Multiple Wasp Stings

LV flashover – lopping head damages insulation

What happened?

A two-person electrical utility arb team were preparing to remove some Category A Spruce branches from the vicinity zone of a low voltage overhead power line, using a pull cord operated lopping head fitted on a set of insulated rods.

The low voltage line was an inter-wrapped bundle of an insulated live line, an insulated neutral line and a bare earth line.

The operator had fitted the lopping head to the top rod and had fitted 5 intermediate rods, he was resting the insulated rod set against the low voltage overhead line bundle. As he lifted up the 5-rod set to fit an additional rod with one hand, the pull rope hanging free down the side of the set, snagged, either at the pull rope insulator insert on a Spruce branch, or on the ground.

The snag caused the operator to lose control of the rod set which slid down the LV bundle it was resting on, the open hook of the lopping head latched over the line bundle and the cutting blade of the lopping head damaged the insulation of the live line. The metal lopping head formed a circuit between the now exposed live line and the bare earth causing a flash over. A loud bang was heard, and the lopping head blade suffered melt damage.

The operative working adjacent to the insulated rod operator was a trainee, with only the basic WI-PS authorisation level. As such the required levels of personal supervision were not as the SPEN authorisation skills matrix.

What can we learn?

All works must be undertaken in reference to PowerSystems. Working on trees adjacent to live overhead lines. OPSAF-12-018 Issue No 4.

The Electrical Networks Association Engineering Recommendation G55 Issue 4, makes the following statements

Lightly insulated covered conductors will provide some protection in the event of accidental contact with other plant but are not deemed to be safe to touch, and so are to be treated in the same way as bare wire conductors for the purposes of determining safe work practices.

It must be borne in mind:

• “where trees are present and have been touching conductors then there will be a strong possibility that abrasion has caused damage to the insulation”
• “Older insulation may be subject to degradation and may not offer full insulation”.

In relation to Category A tree work, the Company’s procedure states:

Where the safe system of work identifies the need for a dedicated lookout to monitor and control operations, a groundsman capable of stopping work (with a whistle) will be appointed to ensure that the required control measures are being adhered to. This requirement will be recorded on the site-specific RAMS.

Such a provision would help to prevent any breach of the live zone with insulated rod sets, and similar potential insulator snagging issues and associated loss of control of the rod set,when working among heavily branched trees.

A correctly authorised person working with the operator, would have recognised, and challenged the unsafe practice, and would have had the knowledge both to recognised that the rope was snagging and the potential consequences of this. And in addition, would have been able to provide the required level of personal supervision for the trainee.

Managers and Team Leaders, in allocating work to works teams, and all SPEN Authorised personnel who are undertaking work, all hold a level of responsibility to ensure they are aware of what Authorisations they and the members of their work party hold, and any limitations on the respective levels of supervision required and what types of work they are allowed to undertake.

Positives

No one was hurt.

The insulated rods and the insulated inserts in the pull rope were maintained in good condition and within their annual test certificate.

The work team immediately set up an exclusion zone to make the area safe and reported the incident to the Network Operator and Management Staff.

Download LV Flashover Bulletin – December 2022

Multiple wasp stings requiring emergency medical treatment

What happened

A chainsaw operator was cutting scrub underneath an 11kV overhead powerline, next to a fence line. Hidden in the undergrowth was a wasps nest which he had unknowingly stood on.

Under the sound of his saw, with ear defenders on and his face visor down, he did not notice the wasp swarm. He initially thought the fence had been electrified against stock, and that he was receiving minor electric shocks from this, he worked on for a moment trying to avoid contact with the fence, it was only when he was continuing to feel sharp pains away from the fence did he realise that he was being stung.

He received over 40 stings in total.

He was attended by the worksite first aider. Due to the volume of stings received, the first aider was concerned enough that he took the operator to the local Accident and Emergency Department.

He was kept in the hospital for the rest of the day under observation. During this time, he went into a reactive shock, and was administered adrenaline and given pain relief.

The Operative was discharged from hospital later that evening. He returned to work after the weekend, on the next working day, to normal duties.

Due to the number of stings that were received, there is a medical concern that he may now have developed a hypersensitisation to wasp stings, as a precaution, the operative has been prescribed an epinephrine auto-injector (EpiPen) to be used immediately if he is stung again in the future.

What can we learn?

Most insect bites and stings will cause a red, swollen lump to develop on the skin. This may be painful and, in some cases, become very itchy.

Most insect bites and stings are not serious, and the pain and skin reaction will recede within a few hours or days. Occasionally they can cause a more serious prolonged reaction which may require further medical treatment.

With multiple stings -- more than 10-20 -- but no immediate evidence of an allergic reaction, you may still need a period of observation in the emergency department or admission to hospital. As mentioned above, it wasn’t until the operative was at the hospital that he went into shock.

The most extreme reaction to an insect sting is anaphylaxis (commonly referred to as anaphylactic shock). It can be a life-threatening and urgent medical attention is required.

Remember, nests can be hidden in long grass and scrub. Be aware of where you are putting your feet when moving through thick undergrowth.

Allergic reactions on site If you have a known allergy or a known reaction to a substance, animal, or insect, you should inform the foreman and the site first aider, to ensure they are aware of your medical condition and where you keep your medication if it is required. You may need to show them how it works in the event you have a reaction and are not able to administer it yourself.

All casualties who have had an intramuscular or subcutaneous (under the skin) injection of adrenaline, must be seen and medically checked by a healthcare professional as soon as possible after the injection has been given.

British Red Cross First Aid App

Ensure you have installed the free British Red Cross app on your phone. This gives quick and easy access to 19 first aid topics with simple step by step guides on what to do.

There is a section specific to allergies/anaphylactic shock with a guide on what to do and symptoms to look out for if you think someone is having a reaction.

Download Multiple Wasp Stings Bulletin – January 2023

Source: Scottish Woodlands