What a Factory Acceptance Test (FAT) Should Include and Why It Matters

Installing new machinery, production equipment or automated systems into a factory is rarely a small decision. For most manufacturers, it involves significant capital investment, careful planning, disruption to normal operations and a clear expectation that the new equipment will improve output, efficiency, quality or safety.

That is why a Factory Acceptance Test, often shortened to FAT, is such an important stage in the process.

A Factory Acceptance Test is carried out before equipment leaves the manufacturer or supplier. Its purpose is to prove that the system has been built, wired, configured and programmed in line with the agreed specification before it arrives on your site. For UK manufacturers, especially those operating in food production, plastics, building products, textiles, packaging or wider industrial environments, a well-managed FAT can prevent costly problems later.

When done properly, a FAT gives your engineering, production and maintenance teams confidence that the system is ready for installation. When rushed or skipped, it can lead to delays, unexpected modifications, safety concerns, commissioning issues and avoidable downtime.

What is a Factory Acceptance Test?

A Factory Acceptance Test is a structured inspection and testing process carried out at the supplier’s premises before machinery, control panels, automation systems or production equipment are delivered to your factory.

It is not just a quick demonstration that the machine switches on. A proper FAT should confirm that the equipment performs as expected, meets the agreed design criteria, complies with relevant safety requirements and is ready to move to the next stage of installation.

The FAT usually involves representatives from the manufacturer or supplier, the end client and sometimes specialist contractors such as electrical engineers, automation specialists or control system providers. Where AES is involved in the electrical infrastructure, control design, panel installation or machine integration, early participation in the FAT process can help identify issues before they become site problems.

The main question a FAT should answer is simple: does this system do what it was designed to do, safely and reliably, before it is shipped to site?

Why a Factory Acceptance Test matters for UK manufacturers

A new machine or production system can look impressive on paper, but the real test is whether it works in practice. A Factory Acceptance Test helps bridge that gap between design intent and operational reality.

For manufacturers, the biggest benefit is risk reduction. If a wiring issue, missing guard, incorrect setting or programming problem is discovered while the equipment is still with the supplier, it can usually be corrected more easily than after delivery. Once the equipment arrives on site, any changes may involve production delays, additional labour, access constraints and knock-on effects for other contractors.

This matters because factory installation programmes are often tightly scheduled. New equipment may need to arrive during a planned shutdown, weekend installation window or phased production changeover. If the equipment is not ready, the consequences can be expensive. Production teams may be waiting, old machinery may already have been removed and customer orders may be affected.

A FAT also creates accountability. It gives everyone a shared record of what was tested, what was accepted and what actions remain outstanding. This helps avoid disputes later and gives your team a clearer handover from supplier to site installation.

What should a Factory Acceptance Test include?

The exact content of a FAT will depend on the type of equipment being purchased. A packaging line, robotic handling system, control panel, conveyor system or process plant will each need a different test plan. However, there are several core areas that should be considered in almost every Factory Acceptance Test.

Review of the specification and design documents

Before any practical testing begins, the FAT should start with a review of the agreed specification. This means checking the equipment against the purchase order, technical requirements, drawings, layouts, control philosophy and any agreed performance expectations.

This stage is important because it confirms that everyone is testing against the same standard. If the specification says the system must achieve a certain throughput, include specific safety features or integrate with existing factory services, those details should be visible in the FAT plan.

For electrical and automation projects, this review may also include electrical schematics, panel layouts, control logic, input and output lists, cable schedules and user interface designs. Any mismatch between what was specified and what has been built should be recorded and resolved before shipment.

Visual inspection of equipment and build quality

A visual inspection is one of the simplest but most useful parts of a Factory Acceptance Test. It allows the client and project team to check that the equipment has been assembled correctly and that the build quality meets expectations.

This should include the physical condition of the machine, access points, guarding, cable routes, control panels, labelling, component placement and general workmanship. For hygienic environments such as food manufacturing, the inspection should also consider cleanability, material suitability and whether the design avoids unnecessary dirt traps or difficult to access areas.

Electrical panels should be checked for neat wiring, secure terminations, correct component identification and safe layout. Poor panel design or unclear labelling can create long-term maintenance problems, even if the machine appears to run correctly during the test.

Functional testing of the machine or system

Functional testing is the heart of the FAT. This is where the equipment is operated to prove that it performs the required tasks.

Depending on the system, this may include running motors, actuators, conveyors, sensors, valves, pumps, robots or control sequences. The test should confirm that the machine starts, stops, resets and responds correctly under normal operating conditions.

For automated systems, the control sequence should be tested step by step. This helps verify that inputs and outputs are mapped correctly, sensors trigger the right responses, alarms appear when expected and operators can control the system safely from the interface provided.

Where possible, the FAT should simulate real production conditions. This may involve running sample products, packaging materials, test batches or representative loads through the system. A machine that works empty may behave very differently when processing actual materials.

Safety checks and emergency stop testing

Safety should never be treated as a final tick box. It should be built into the FAT from the start.

A Factory Acceptance Test should include checks on guarding, interlocks, emergency stops, light curtains, access doors, safety relays and any safety related control functions. The test should confirm that the system responds correctly when a safety device is activated and that it cannot restart unexpectedly after a fault or emergency stop.

For UK manufacturers, machinery safety is a key responsibility. While the FAT does not replace a full site risk assessment or final validation after installation, it does provide an important opportunity to identify design or integration issues early.

It is also worth checking how the machine will interact with people in real working conditions. Can operators reach controls safely? Are maintenance access points practical? Is the reset procedure clear? Are there any pinch points, trapping risks or areas where behaviour on site may differ from the supplier’s test environment?

Electrical and control system verification

For industrial equipment, the electrical and control system is often where the biggest commissioning issues arise. A good FAT should include careful verification of the electrical design, control panel build and automation logic.

This may include checking power requirements, motor ratings, protective devices, control voltages, earthing arrangements, input and output signals, network connections and communication with other systems.

If the equipment will be integrated into an existing factory, compatibility is especially important. Older factories may already have established control systems, power distribution constraints or communication networks. Identifying those requirements during the FAT helps reduce installation risk once the equipment arrives on site.

For manufacturers planning wider automation upgrades, the FAT is also a useful moment to consider futureproofing. The system should not only work today but be capable of supporting future monitoring, energy data, remote diagnostics or additional control integration where required.

Performance testing against agreed criteria

A Factory Acceptance Test should not only prove that a system works. It should prove that it works to the level agreed.

Performance criteria might include cycle time, throughput, accuracy, temperature control, pressure control, speed range, repeatability, energy use or product handling quality. These criteria should be measurable wherever possible.

For example, if a packaging system is expected to handle a certain number of units per minute, the FAT should test that figure under realistic conditions. If a process control system must maintain a stable temperature or flow rate, the test should demonstrate that performance over a suitable period.

This is where clear documentation matters. If performance standards are vague, acceptance becomes subjective. If they are measurable, the FAT becomes a practical decision-making tool.

Documentation and operator information

The FAT should also confirm that the right documentation is available. This may include manuals, electrical drawings, parts lists, software backups, safety documentation, test certificates and maintenance instructions.

For factory teams, documentation is not just paperwork. It supports safe operation, future fault finding, planned maintenance and compliance. If drawings are missing, manuals are incomplete or software backups have not been provided, your maintenance team may struggle later.

It is also worth reviewing operator instructions during the FAT. If the interface is confusing, alarms are unclear or reset steps are difficult to follow, these issues can often be improved before the system is delivered.

Recording actions and agreeing what happens next

A Factory Acceptance Test should end with a clear record of findings. Any defects, changes, incomplete items or agreed actions should be documented, assigned to an owner and given a target completion date.

Not every issue discovered during a FAT will prevent delivery. Some minor actions may be acceptable to close out during installation or commissioning. However, critical issues affecting safety, performance or integration should normally be resolved before shipment.

This final record is essential because it protects both the manufacturer and the client. It confirms what has been accepted and what still needs to be completed before the system moves into site installation and Site Acceptance Testing.

FAT and Site Acceptance Testing are not the same

It is important to understand that a Factory Acceptance Test and a Site Acceptance Test are different stages.

The FAT proves the equipment at the supplier’s premises before delivery. The Site Acceptance Test, or SAT, proves the equipment once it has been installed in your factory and connected to the real services, environment, products and operators.

Both are valuable. A FAT reduces risk before the equipment arrives. A SAT confirms that the installation works properly in its final operating environment.

For older factories, this distinction is particularly important. The equipment may perform correctly at the supplier’s site, but once connected to existing power supplies, compressed air systems, extraction, conveyors, control networks or production processes, new issues can appear. A strong FAT makes the SAT smoother, but it does not replace it.

How AES supports FAT planning and machine installation

AES supports UK manufacturers with the electrical and automation elements that sit around new machinery and equipment installation. This can include reviewing electrical infrastructure before equipment purchase, advising on power and control requirements, supporting panel design, preparing site services and assisting with installation, testing and commissioning.

Where a Factory Acceptance Test is planned, AES can help manufacturers ask the right technical questions before equipment leaves the supplier. This is particularly useful where the machine needs to connect into existing factory systems or where production downtime must be tightly controlled.

By involving electrical and automation specialists early, manufacturers can avoid common issues such as insufficient supply capacity, incompatible control signals, unclear cable routes, poor panel documentation or missing safety integration details.

Final thoughts: a good FAT protects your investment

A Factory Acceptance Test is not just a supplier formality. It is a practical safeguard for your investment, your production schedule and your operational team.

For UK manufacturers investing in new equipment, the FAT should be treated as a key project milestone. It gives you the opportunity to test, question, document and correct before the equipment reaches your site. That can make the difference between a smooth installation and a costly delay.

The best FATs are structured, detailed and realistic. They involve the right people, test against clear criteria and leave no uncertainty about what has been accepted.

If you are planning new machinery, automation upgrades or production equipment installation, AES can help you assess your electrical infrastructure, prepare your site and support the technical checks needed to make your Factory Acceptance Test and final installation a success.