Emerging Voltage Drop Solution Saves Grid Operator $9.4Million in cable costs

13 Sep 2021

Voltage Drop Savings Tunnel Cabling

Est Reading time: 9 minutes

“What is voltage drop? How do I calculate it? And why does it cost a fortune to solve this problem!?”


In most electrical design processes, overcoming this problem can be an extremely costly affair.


The goal is to satisfy the maximum allowable voltage drop limits in the electrical system, no matter the size of the load. 


Yet the existing solutions to long-distance cable runs are causing a significant dent in project budgets. 


So if you’re looking for practical ways to finally put an end to this frustrating problem…


You’re in the right place.


In this article, we reveal our “No BS”, field-tested methodologies on how you can successfully eliminate voltage drop, permanently.


To kickstart your journey, it is crucial to first understand the what, and how’s of voltage drop.


Let’s get started.

What Is Voltage Drop?

A voltage drop in an electrical circuit typically occurs when a current passes through the cable.

It is related to the resistance or impedance to current flow with passive elements in the circuits including cables, contacts and connectors affecting the level of voltage loss.

So the longer the length of the cable (or circuit), the greater the voltage loss. 

Let’s take a look at this simple, step-by-step method to calculate your voltage drop.

Step 1: Take the value from the volt drop table (mV/A/m)

Step 2: Multiply the ACTUAL current in the cable (NOT the current rating)

Step 3: Multiply by the length of run in METRES.

Step 4: Divide results by 1,000 (to convert millivolts to volts)

Here’s an example of how the voltage drop formula (VD) works – just for you:

VD = (mV/A/m x I x L) / 1000)

VD = (Step 1 x Step 2 x Step 3) / Step 4)

Voltage Drop Table - Ashley Edison

Think of the water that flows out of a tap and then down a long hose.

The farther away you get from the tap, the weaker the stream of water will be that flows out of it.


The same is true of electricity through wires: 


“The farther the electricity gets from the source, the weaker the current will be.”


So now that we have a better understanding, let’s deep dive into more details.

Having trouble with Voltage Anomalies? Get in touch with us at [email protected].

In the electrical world where the threat of voltage drop is persistent and inherent.


These problems can also cause total distress to engineers.


So, this leads us to a very important question…


What is the negative impact on your equipment?
The consequences will shock you…)

Disastrous Consequences Of Voltage Drop

Industry studies show that a 20% voltage drop lasting just 50 seconds can be extremely detrimental to your equipment’s health.


The outcomes can vary from horrifying equipment malfunction to complete facility downtime.


Here are 9 harmful consequences:

Maximum allowable Voltage Drop In Australia

In most parts of Australia, the nominal single phase supply voltage is 230 volts +/- 6%, this represents a range between 216.2 and 243.8 volts. (With the exception of Western Australia remaining at a nominal voltage of 240V +/- 6%).

As specified in clause 3.6.2 of AS/NZS 3000:2018 on standard installations, the maximum permissible voltage drop between the point of supply and any point of the installation is as follows:

Here’s a Rule of Thumb.


The following limits can be used as a guide to assist with design:

These undesirable problems can post a challenge to electrical engineers.

But what exactly causes voltage drop to happen?

Let’s find out below.

What Causes Voltage Drop?

You may want to sit up for this.


Common challenges when trying to eliminate voltage drop, is the lack of understanding of what causes it.


In an environment with no room for mistakes, engineers leave nothing to chance. No guesswork, no trial and error.

Here are the 6 determining factors that cause voltage drop to happen:


Now that you have a better understanding of all the primary conditions that cause voltage drop.


You would be wondering.

How Can I Minimise Voltage Drop?

Well, your search is finally over.


There are basically 2 ways of overcoming this issue:


  1. Conventional ways of minimising voltage drop.
  2. Adaptive way to eliminate and save.

Let’s investigate..

#1. Conventional ways of minimising voltage drop.

These methods have been the default solutions for minimising excessive voltage drop:

  1. Compensating voltage drop using larger cross-sectional sized cables. This offers less resistance / impedance to current flow.
  2. In power distribution systems, a given amount of power can be transmitted with less voltage drop if a higher voltage is used.
  3. Increasing the quantity of the cables will decrease the resistance – causing voltage drop to decrease, and increase your overall efficiency. (This will also lower overall power loss!)

If you’re at the preliminary design stage of your project, you may find that the costs involved in these conventional methods will make a significant dent in your budgets…

And that’s how some processes come to a screeching halt.

On the other hand, ensuring a regulated and stabilised voltage supply should always be a priority.

After all, the failure of your system’s assets is the very risk that must be mitigated if not eliminated..

Underground Tunnel Cabling - Voltage Drop Ashley Edison Feat Img
#2. Adaptive way to eliminate and save.

So how are grid operators and consultants effectively eliminating voltage drop, saving millions on cable cost?

Case Study

(2017 Underground Transmission Cable Tunnel Project)

  • Distance Between Point Of Supply And Point Of Installation: 7.4 km
    Max Design Current: 134.33 A
  • Point Of Supply: 500V
  • Desired Voltage Value At Point Of Installation: 400V
  • Cables Used: XLPE / SWA / PVC / Armoured Cables

In efforts to sustain the reliability and security of electricity networks, a Grid Operator completes a $2.4-billion project, spanning a 40km network of three tunnels built to house 1,200m of transmission cables.

The objective was to ensure voltage values at the load end were kept within the maximum allowable voltage drop levels at 4% of 400/230V (376V / 216.2V).

However, in just one portion of the project alone, the original electrical design utilising conventional methods of increasing the quantity and sizing of cables:

Would have amounted to an estimated $12 million in cable costs.. 

What was required to overcome the key issue of voltage drop and high cable costs – was a solution that is efficient and cost-effective:

And in 2017, Ashley-Edison’s Automatic Voltage Regulators were deployed to:

  • Boost low voltage levels at every load end of the cable tunnel.
  • Regulate and maintain an optimum output voltage, even if the load changes.

Through a carefully designed configuration, over a dozen Automatic Voltage Regulators have helped achieve the objectives and save over $9 million dollars in project budget.

These savings solely came from what would have otherwise been spent on cabling costs.


In Conclusion

The key to effectively eliminate voltage drop problems is essentially having a solution that is both on point, and on budget.


If you need help solving your voltage problems or you wish to explore more innovative ways to optimise your electrical system, let our expertise be your guide.


Are you a firm believer in conventional engineering methodologies?


Are you against the idea of other field-tested alternatives to solve your power problems?


To learn more about how Automatic Voltage Regulators can benefit your electrical design, drop us an email at [email protected] and we’ll be happy to help you chart the best solution for your power needs.



P.S. Want to know how other esteemed companies are overcoming their power problems?

Click here to find out more.

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Stay Safe With Greater Protection

As safety is our utmost priority, Ashley Edison prepares for every scenario possible
—taking the puzzle out of your protection.

Designed And Engineered With Safety In Mind

We leave nothing to chance when it comes to larger capacity units (≥400KVA). By installing high-quality protective acrylic shields in front of live parts, we ensure the safety of your personnel at all times. For enhanced protection during installation, all distances between uninsulated metal parts, busbars, and cable sizes are compliant with IEC61439-1 and IEC 61439-2 guidelines.

Outfitted with fireproof cable trunking, this protective solution safeguards against long fire exposure even in hazardous areas and explosive atmospheres—providing maximum safety for mission critical applications.

Fuss-Free Installation. Seamless Operations.

To ensure ease of installation, Ashley Edison addresses the concerns of contractors and installers by keeping it simple.



We keep the installation process simple and streamlined by allowing sufficient working space for installers. Taking the nut and bolt intrusions into consideration, we ensure that the distance between the uninsulated metal parts, the busbars, and cable sizes are compliant with IEC61439-1 and IEC 61439-2 guidelines.


Even in units with larger capacities, all busbar terminals are clearly marked out, and well positioned in line for easy identification of individual input and output terminations. Installation of these terminations are similar to those practised in high voltage transformers.

Easy Maintenance

Annual Ocular Maintenance
Visual Inspection 230

Conduct Visual Inspection On Voltmeter:

Ensure reading is set to your desired set output voltage value (e.g. 230V).

LED Status

Ensure LED Status Indicators are at “Normal”.

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Visual Observation Of Variable Transformer Surface:

Use airbrush for dusty environments if necessary.

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Visual observation if carbon brush is not worn out.

Moving Motor

Conduct visual inspection to check variable transformers are all regulating (moving).


Accuracy. Beyond Imagination.

The digitally enhanced Ashley Edison MBB Card ensures pinpoint voltage stabilisation against the most erratic anomalies, allowing you to protect precious uptime, effortlessly. Harnessing ultra precision capabilities to produce some of the tightest output voltage tolerance available in the industry, the Ashley Edison MBB Card delivers ±0.5% voltage accuracy, enabling your load equipment to enjoy optimal voltage supplies, regardless of load change in your electrical system.

Expert Digital Control

Utilising the advantageous measurements of true RMS, the Ashley Edison MBB Card’s reads both perfect, sinusoidal waves, as well as complex, distorted non sinusoidal waves—up to 0.1V accuracy. Coupled with lightning fast response time of 1.5ms, this expert digital control feature equips your load with total voltage protection that is precise, continuous and ultra responsive.

AE Digital Control Display_230v

Universal Presettable Function

The Universal Presettable Function onboard the Ashley Edison MBB Card allows seamless control of your desired output voltage value on all 3 Phases—with just a touch of a button. This multifunctional feature enables each AVR to fully operate with just 1 card, instead of separate cards for each individual phase. Fitted LED Output Voltmeter Display and Alert Indicator better facilitates easy status monitoring while performing maintenance on your AVR.


Microcontroller Unit (MCU)

MicroController Unit (MCU) helps you to deliver high speed and reliable efficiency in the AVR’s operations with less heat generation and reduced power consumption. Used in Supercomputers, Surface Mount Technology (SMT) allows components in the Ashley Edison MBB Card to be aligned closer together, creating a more compact and lightweight end product. Additional safety wire-to-board feature establishes fail-proof connectivity between circuits—so you can work safely on your AVR.