Working with electricity is dangerous, regardless of whether it’s high voltage or low voltage. Dale West gives his ten tips to stay safe while working.

Working with both high voltage (HV) and low voltage (LV) can be dangerous. People will assume that arc flash incidents make HV riskier but cheap, low-quality equipment often seen in LV installations means that they’re both equally as dangerous.

And when LV installations fail, they fail at the worst possible time and in spectacular fashion, usually when someone isn’t wearing arc flash PPE.

This article takes a break from my usual storytelling to share my ten issues with HV and how to address them. However, LV presents very similar risks so these issues can also be used for LV personnel.

1 Clear instructions

We all make mistakes, we’re only human. Because of this, we don’t leave the process of HV isolations up to the sole responsibility of the person performing the operations. We only perform HV isolations under the strict instructions written on what we call a Switching Program.

A Switching Program is planned, developed and written every time any switching is about to take place because every time we switch, the hazards may be different.

The biggest issue with developing a switching program is in the wording. Most people write instructions the way they communicate. We know what we’re talking about and rarely take the time to consider if there is any way at all it can be misinterpreted.

True story: my wife and I were quickly getting ready to go out for dinner. She threw on a shirt, handed me a spray bottle of water and asked me to spray the “wrinkles”. This was an opportunity I could not pass up. I gladly took the spray bottle, quickly, but carefully aimed it and sprayed her in the face.

I know, I know… you’re thinking I had a near-death experience, but I am not a brave man; I identified the hazard, carefully assessed the risk and did it anyway. I am fortunate she loves my sense of humour.

I do the same when assessing switching programs. I deliberately try to twist every instruction I’ve written to see if anyone could be confused and think it means something else.

For instance, someone issues the instruction to “test for dead”. This can mean a lot of different things, and we will address this later in the article. In a Switching Program, almost every single time they write “test for dead”, what they really mean is: “Check for de-energisation”. This can be done by simply checking if the lights have gone out on the stacker, but I have had experienced HV operators tell me they take out a shifter and remove panels from ring main units (RMUs) to access the HV cables.

Before we issue instructions, make sure you fully understand the problem from every possible angle. Look at all the different ways the solution could be explained. Use as few words as possible, while providing enough information to ensure no one could possibly misunderstand the instructions.

2 Remote switching

This is the latest magic solution everyone is focusing on. Remote switching is great for the person conducting the switching as they are removed far from the arc flash boundary. Other personnel in the field, however, are not removed from the hazard if the incorrect switching sequence is conducted, or the wrong piece of equipment is operated.

Operators are required to be as careful with their equipment selection, sequence and checking as they would be if they were standing in front of the device, concerned for their own safety.

3 Isolating LV systems

AS/NZS 3000 Clause 7.6 High voltage electrical installations states: “For protection and Earthing purposes, this clause also applies to all the electrical equipment up to and including any LV cables and switch gear associated with the HV transformers.”

You shall isolate and Earth all possible means of supply; if at all possible, this includes LV cables on the LV side of the transformer, up to and including the first piece of LV switchgear.

This also includes isolating voltage transformers and disabling the LV control circuit.

4 Verifying: Operation or de-energisation

This is one of the most challenging things to do. The reason is that there is no ‘one solution’ that fixes all problems due to the multiple sources of supply from multiple directions in HV RMUs.

There are three main ways to check the operation of metal-clad switchgear.

• Semaphores (fancy word for flag) every switchgear will have semaphores.
• Inspection windows allowing you to make a positive check of the switching contacts.
• Voltage Indicator Panel (VIP) or live line indicators.

Now, which one to use? That is what confuses. It depends on what you want to verify.

It’s a combination of whether you’re checking the equipment operated correctly or checking the cable is de-energised and this will depend on whether the equipment is in a radial feeder or a ring feeder.

I don’t have the space to include the information here. Just be aware you need to know exactly what you are wanting to check and the most accurate way of doing it.

5 Test before you touch

We all know we shall test before we touch, however, there is far more confusion out there than you would expect about how this is done.

You may have heard of a Modiewark or a Fameca Vector to check exposed conductors. The issue is, what are they testing?

Most people believe it’s testing for dead; this is not the case. These devices are proximity testers, basically, volt sticks. We never use a volt stick to test for dead on LV and we don’t use it to do the same on HV.

We are merely checking for de-energisation so we can apply an Earth. We check before we earth and then we test before we touch.

6 Earthing

Every isolation point must have at least one Earth. Why at least one?

An overhead line may not have an Earth switch at the isolation point. You will have to apply a portable Earth device (PED) you may know these as ‘working Earths’. When PEDs are used by the HV operator for isolation, they’re called a program Earth, operator Earth or isolation Earth.

As these are portable, you will have to calculate the prospective fault current and may need to put more than one set of PEDs in parallel to ensure your earth will handle the fault current long enough to allow the protection device to trip. Unfortunately, most people render the isolation unsafe by neglecting to conduct this calculation and only applying one set of PEDs.

We Earth overhead lines to discharge residual energy, as well as continual induction and capacitance. Residual energy will still be in the cable after isolation. Induction in the cable is caused by nearby live cables that can be dozens of meters away. Capacitance that can reach thousands of Volts and has proved fatal is built up due to friction on the line caused by the breeze.

7 Phase out

Everyone is familiar with phase rotation on a radial feeder and how it will cause motors to run in reverse.

Connecting the phases incorrectly on a ring feeder, however, will not send the motors in reverse; it will send your life expectancy to run in reverse when you close that last switch to connect the ring.

The unfortunate situation here is you would have a potential difference across the open switch equaling the system voltage; closing that switch causes a phase-to-phase short circuit.

Conducting a simple phase sequence test, which we call a ‘phase out’, is all that is required to prevent this from happening. With the use of either phase-out sticks on overhead lines, or a multimeter on live line indicators we can make sure we have no potential difference across each phase at an open switch before we close it.

8 A vital addition to the LVR kit

There is one thing you can do right now that’s free and will dramatically improve the chance of survival from an arc flash incident.

In the event of an arc flash, the most likely injury will be burns. Every switchroom will have an LVR kit that will have a fire blanket, burns dressing and the bag itself is designed to carry water.

Where are you going to fill the bag with water? Besides every LVR kit, keep a couple of 20L bottles of clean water. Hopefully, you will never need them, but if you do, it will make a world of difference.

9 Switching assistant

Would you trust a surgeon who uses an orderly to assist them in surgeries? In HV, we don’t use the equivalent of an orderly or even a trained surgical assistant. In HV, we use the equivalent of a more experienced surgeon to assist in surgery.

When switching HV equipment, to minimise any mistakes, we don’t rely on the actions of just one person. Everyone makes mistakes, everyone can have a bad day, plagued by distractions. The hope is that a second experienced person double-checking everything before, during and after the smallest action, will pick up on anything that might create a hazard.

The very term switching “assistant” in my opinion, causes a problem. It doesn’t help there’s nothing in legislation that even mentions the need for an assistant. Most small companies will argue the operator, at best, might require a safety observer.

I would like the role of the switching assistant referred to as the ‘switching director’ or ‘supervisor’, as the HV assistant is the person who is usually more qualified and experienced than the switching operator.

10 Authorising process

These days, only those trained by an RTO and authorised by the owners/managers (authorising person, or ‘AP’) of the HV equipment are permitted to operate the HV switchgear.

The AP is responsible and accountable for who they authorise to manage the HV systems. Most often the AP, however, has no experience or understanding of the hazards involved in operating an HV system.

We have VOCs for the likes of operators of forklifts, but nothing to assist the AP to authorise HV operators. So, the challenge is, how does an AP know if the candidate is competent to switch their system?

After completing a five-day course (Some RTOs make it worse by offering a two-day course) the candidate is sent back to the site to hopefully be trained by the existing authorised operators on site, if there are any… and if they have time to train them properly… and if they are competent… and if they actually know all the hazards associated with HV on their site… and if they know how to train. I know, a lot of “ifs”.

The AP in consultation with the existing operators, and on their say so, will issue a letter of appointment to authorise the candidate to safely manage their HV system and teach the next HV operators.

As you can see, there is a lot of responsibility on the AP and they must place a lot of trust in those that are already authorised.

Most, if not all of, the incidents we see, can be remedied during this authorising process.

If we improve the authorising process we will identify the hazards, write better procedures and programs, improve our checks and tests, apply better Earths, appoint more qualified people, employ better control measures, reduce the risks, have less downtime, fewer incidents and save lives.