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Current Sensors: the tiny tool that could help slash your energy use

A photo of Energy Manager holding a CT clamp in their hand

Energy prices are higher than ever, and businesses are under great pressure to cut the costs to remain profitable.

There are many ways to do this, from turning off lights when you leave a room to shutting down an entire building but, as with any such trade-off, it’s about the return on the investment – and this is much easier to see when you have an accurate picture of where and how your energy is used.

Whether catering for hundreds of employees or no more than a dozen, a working office environment will have numerous energy needs – lighting, environmental control systems such as heating, ventilation and air conditioning (HVAC), catering facilities, fire/security systems and more.

In-house IT systems can run whole rooms full of power-heavy servers running 24/7. Even the coffee machine in the break room is using power. And that’s just an office – factories, warehouses and other facilities have unique and wide-ranging energy requirements.

So how do you know where to cut down?

Every month, your energy provider looks at how much energy you’ve used, and charges you appropriately. Your meter readings and bills give you an accurate reflection of how much energy your site has used over the past month. But do you know how you’re using that energy, or how efficiently?

Without this information, it can be difficult to know whether energy saving efforts are actually making a difference. For example, taking simple steps like emailing staff and asking people to turn lights off when they leave a room might sound like a good idea. But a month later, has it made a change? Did your staff actually do anything differently? Did it reduce your energy bill? When all you have is a meter reading it’s difficult to know what measures have an effect.

The first step in making improvements is knowing where you are. You need an accurate way to measure where the energy is being used, by what and how much. This is where CT Clamp Current Sensors come in.

An image of a CT clamp that is installed around a cable

CT Clamps attach around the outside of live conductors, such as the wires going to different circuits in a fuse box. They can be installed in a live circuit, without requiring any changes to the circuitry. You don’t even need to shut the power off to install them and, if you use self-powered wireless sensors, they can be installed with minimal disruption to a site.

The data collected can be passed straight to the cloud for analysis and storage, without any local IT resources or administration required. Using 3G/4G, even the data network on the site can be bypassed, providing an entirely standalone monitoring system.

These allow you to measure and track the energy being used by different parts of a site, such as the lighting circuit, HVAC, or manufacturing machinery. Once you’re collecting this data, you can really start to see how and where your energy is being used.

An accurate picture of how your site uses energy can be hugely valuable when planning energy saving measures and determining their value.

Motion-activated lighting might be an energy saving measure, but until you know where energy is being wasted, it’s difficult to know. Nobody wants to spend money installing smart lighting, only to learn it doesn’t save any energy at all. By tracking the energy used by individual fused circuits you can not only see where there is potential to reduce energy, you can also see the effects of any measures taken in real time.

a shop floor at a factory
A Facilities Manager checking data on his laptop
a hologram of the earth surrounded by sustainability icons held in hands

But reducing energy isn’t just about switching lights off and keeping windows closed. There are more complicated measures which can be taken, particularly with energy-hungry equipment in a factory-type facility.

Some manufacturing machinery has a “start up” process which uses a lot of time and energy. By monitoring and tracking the energy on a per-machine level, you can calculate the costs of the start-up. By tracking the energy usage over a period of time, you can determine exactly when to shut this machine down and when to let it stand by. It might be possible to perform some tasks at different times, when the energy is charged at a lower rate. Or there might be more efficient ways to make use of non-grid power sources such as solar panels and heat pumps.

When deciding whether to upgrade to more efficient equipment, measuring the true values of the energy used by the equipment can help create an accurate return on investment calculation, as well as showing the data to demonstrate the effects of the upgrade.


Some things might become immediately apparent, such as discovering the office air conditioning is on every weekend or noticing the type of lighting being used in one area is less efficient than the rest of the site. Other things might be less obvious but become clearer as you collect and analyse the data.


Chris Green, Technical Support Manager

It’s not just about saving energy

Monitoring energy consumption can be a valuable part of a preventative maintenance schedule. Equipment which suddenly starts using more or less energy is often an early sign of a malfunction or unseen wear and tear. By monitoring the energy consumption of all equipment side by side you can be quickly alerted to any device which is behaving strangely.

Careful consideration of how we use energy is more important now than ever, both for economical and environmental reasons. We all want to get to the most efficient point possible, and the first step is knowing where you’re starting from. CT Clamp current sensors, combined with the right software to store, analyse and display the data they collect, are your first move towards understanding your starting point.

When your site is being monitored with CT Clamp current sensors, you can really see where improvements can be made, and watch it happen in front of your eyes!

written by Chris Green, Technical Support Manager at Pressac

as published in the March issue of Energy in Buildings and Industry Magazine (page 30)

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