Programmable Logic Controllers

Programmable Logic Controllers in the UK: Where to Buy, How to Choose, and Top Picks from Expert Electrical and Beyond

Why PLCs matter for UK workshops, factories, and home automation

If you’ve ever wondered what keeps conveyor belts moving, pumps humming, or a smart greenhouse ticking over, the answer often comes down to a Programmable Logic Controller, or PLC. Think of a PLC as the brain of an automated system — compact, rugged, and designed to handle real-world inputs and outputs faster than you can blink. Whether you’re retrofitting a workshop in a converted mill or wiring up a small production line in a business park, a good PLC turns electrical chaos into predictable performance.

Where to shop for PLCs in the UK: an overview

Shopping for PLCs in the UK is easier than ever thanks to specialist stores and general industrial suppliers. If you’re looking for dedicated stock, helpful technical data, and product ranges that include both entry-level devices and pro-grade controllers, retailers such as Expert Electrical, RS Components, Farnell, Rapid Online, and Screwfix are all good places to start. Each outlet has its strengths — some excel at technical support, others at range or price — so knowing what you need will save time and money.

Expert Electrical — specialist selection and examples from the data

Expert Electrical stands out as a specialist supplier for control components, and the product snippets in the supplied data show the sort of kit you can expect there: programmable boost controllers, multi-channel programmers, and compact smart relays. Products like the Sangamo Electronic Boost Controller with programmable operation and the Sangamo Choice Plus Programmer 3 Channel illustrate the kind of niche, programmable control modules that suit pump control or energy-management tasks. Schneider’s Compact Smart Relay is another example of a compact, user-friendly controller aimed at small automation projects.

RS Components — broad range for engineers

RS is often a first stop for engineers and maintenance teams because it combines a huge product catalog with datasheets, application notes, and rapid ordering. You’ll find everything from Siemens and Omron PLCs to I/O expansion modules and DIN-rail mount accessories. If you want variety and technical depth, RS typically has multiple brand options for every budget and specification.

Farnell (Newark) — pro-grade stock and datasheets

Farnell, also known as Newark for some international buyers, is aimed squarely at professionals who need proven parts and full technical support. You’ll see pro-grade PLC options and industrial relays here, plus certified parts for projects that require traceable components. Their stock suits lab, industrial, and academic applications where reliability matters.

Rapid Online — great for hobbyists and education

Rapid Online is a strong pick if you’re a maker, educator, or running small automation projects. They lean toward accessible products and often stock compact PLCs, programmable relays, and learning kits that make it simple to experiment before you commit to larger systems. It’s a good place to test an idea without breaking the bank.

Screwfix and Toolstation — accessible parts and relays

For basic control gear like relays, timers, and simple smart relays, high-street suppliers like Screwfix and Toolstation can be surprisingly useful. These outlets won’t replace a specialist industrial supplier for complex PLC systems, but for a quick relay or a compact smart module to control motors and pumps, they’re convenient and quick to visit.

Popular PLC brands and modules to consider

Not all PLCs are created equal — and brands matter. On the pro side you’ll see Siemens, Schneider Electric, Omron, Rockwell/Allen-Bradley, Mitsubishi, and Beckhoff. For compact, entry-level controls there’s Schneider’s Compact Smart Relay family and other “logic relay” style devices that bridge the gap between a relay and a full PLC. The Sangamo items mentioned earlier fit into this space as programmable controllers for specific industrial tasks like boost control and channelized programming.

What makes a brand stand out?

Choose a brand based on support, software maturity, and module availability. Siemens is ubiquitous in large plants, Schneider makes user-friendly compact units, Omron and Mitsubishi are strong in motion and discrete control, and Beckhoff is excellent for PC-based control. If you want long-term availability and easy sourcing, picking a widely supported brand will make life easier when you need spare parts in a year or two.

How to choose the right PLC for your project

Picking the right PLC is more than cherry-picking a price tag. Start by listing the inputs and outputs you need: how many digital inputs, how many outputs, do you need analog channels for sensors, and are there special modules like high-speed counters or thermocouple inputs? Next, consider communications — will your system need Ethernet, Modbus TCP, Profinet, or serial links? Also think about environmental needs: will the PLC live in a dry control cabinet or near dusty machinery? The operating temperature should be checked in Fahrenheit for UK shops; most industrial PLCs run comfortably up to about 140°F but check the spec sheet.

Size, mounting, and footprint

How big is your control cabinet? PLCs and I/O racks are typically specified in inches for height and depth when you talk to installers. A compact smart relay or small PLC often fits into a panel just 6 to 12 inches high, whereas modular racks for larger systems can be 18 inches or taller. Plan clearance for wiring and breathing space — cramped cabinets are a headache when you need to service components.

Power requirements and electrical safety

Most modern PLCs run on 24V DC control power, but many compact relays and smart controllers accept 120V or 230V AC input. Make sure your chosen device matches your site’s supply. If you’re not sure, it’s a good rule to check the datasheet before adding items to your cart. And never underestimate the value of proper fusing and circuit protection — it keeps the control hardware alive and well.

Programming languages and user experience

PLCs are programmed in several standard languages: Ladder Logic is the classic and widely supported; Function Block Diagram suits continuous processes; Structured Text is powerful for algorithmic tasks. Compact smart relays often have simplified graphical interfaces and built-in templates, making them ideal if you don’t want to learn a full IEC 61131 environment. If you’re just starting out, pick a platform with good tutorials and a visual editor.

Human-Machine Interfaces and SCADA integration

If you want operators to interact with the system, consider a PLC that supports easy HMI integration. Many compact PLCs offer simple web dashboards or HMI compatibility so you can display statuses and change settings without diving into the PLC program. For larger plants, look for vendors with proven SCADA integrations so historical data and alarms can be logged and visualized.

Installation, maintenance, and safety tips

Installing a PLC is as much about good practice as the hardware. Keep wiring neat and labelled, use ferrules on stranded wire, and route power and signal cables separately to reduce noise. For maintenance, schedule periodic backups of the program and keep a local copy on a thumb drive or a version control system. Also implement lockout/tagout procedures whenever you work on live machinery — safety first, always.

Cooling and environmental control

PLCs can tolerate a fair range of temperatures, but excessive heat shortens life. If your cabinet tends to climb beyond 95°F in summer, add ventilation or a small fan. Dust and moisture are your enemies; IP-rated enclosures and silica gel packets can give you peace of mind in tougher environments.

Budgeting: typical price ranges and what affects cost

Price varies hugely based on capability. A simple smart relay or compact controller might start in a low two-figure price range, while modular PLC racks with multiple I/O, specialty modules, and network cards can run into several hundreds or even a few thousand. Brand, communication modules, ruggedness (for harsh environments), and software licensing all affect cost. If you’re on a tight budget, prioritize the I/O you need today and leave room for expansion later — expansion modules are cheaper than swapping the whole brain.

Finding the best deals and price lists

Stores will sometimes publish price lists or promotions for PLC lines, especially when they run clearance or seasonal sales. Specialist suppliers like Expert Electrical often feature targeted products such as Sangamo controllers or Schneider smart relays, and they may bundle accessories like DIN-rail adaptors and terminal blocks. Large distributors like RS and Farnell also publish pricing and stock levels online, so you can compare quickly. If bulk buying, ask about trade discounts — many suppliers offer better pricing for multiple units.

DIY projects versus hiring a professional

Are you the sort of person who loves wiring schematics and writing ladder logic at midnight? Then a compact PLC or logic relay might be a satisfying DIY project. On the other hand, if your automation involves mains voltages, heavy machinery, or safety-critical controls, it’s wise to bring in a licensed electrician or control engineer. They’ll help with electrical compliance, safe isolation, and robust programming — sometimes a small upfront cost saves a lot of downtime and costly mistakes later.

Real-world examples: using Sangamo and Schneider devices

Looking at the product snippets from expert suppliers, you can see real applications. A Sangamo Electronic Boost Controller can automate pump operation for water systems, providing programmable thresholds and time-based controls. The Sangamo Choice Plus Programmer 3 Channel is a neat device for managing multiple channels — handy for multi-pump setups or staged control. Schneider’s Compact Smart Relay family is ideal for small machine controls, lighting sequences, or HVAC tasks where a full PLC would be overkill. These devices are like different sizes of toolbox — each fits different jobs.

Final buying checklist for PLCs in the UK

Before you hit buy, ask yourself: Do I know the exact I/O needs? Which communications matter? Is the operating environment dusty or humid? Do I want a friendly visual programming interface or a professional ladder editor? What’s my expansion plan? Once you can answer these, shortlist vendors like Expert Electrical for specialist modules, RS and Farnell for breadth and datasheets, and Rapid for experimental gear. That checklist keeps impulse buys from becoming costly regrets.

Conclusion

Programmable Logic Controllers are the unsung heroes of modern automation. Whether you’re updating a production line, wiring a water system, or experimenting with a home automation build, choosing the right PLC and supplier makes all the difference. Expert Electrical offers focused control components like Sangamo controllers and Schneider smart relays, while larger distributors such as RS Components, Farnell, Rapid Online, and even high-street outlets can fill out the rest of your shopping list. Plan your I/O, consider environmental needs in Fahrenheit, pick a brand with good support, and balance DIY enthusiasm with safety. With the right approach, you’ll have a reliable control system that keeps operations humming for years.