Three-Phase EICR Testing for Manchester Factories and Workshops
Most residential EICRs deal with single-phase supplies — one live conductor, one neutral, one earth. The consumer unit sits under the stairs, the inspection takes three to four hours, and the report covers twenty to thirty circuits. It is straightforward work.
Walk into a factory or workshop on a three-phase supply and the picture changes completely. The distribution is larger, the voltages are higher, the load is heavier, and the installation is more complex. Three-phase EICRs take longer, require different test equipment, and need an engineer who understands industrial distribution. This page explains what is different, what it costs, and how to prepare your premises so the inspection runs smoothly.
Quick answer: A three-phase EICR inspects and tests a commercial or industrial electrical installation supplied at 400 V three-phase. It covers all distribution boards, sub-mains, protective devices, earthing and bonding, fixed machinery connections and socket circuits. For a typical Manchester factory or workshop unit, expect the inspection to take a full day — sometimes two for larger sites — with costs ranging from £600 to £2,500 depending on the number of distribution boards and circuits. Call 0161 706 1360 to arrange a survey and fixed-price quote.
What Makes Three-Phase Different from Single-Phase?
The fundamental inspection process is the same — visual inspection, dead testing, live testing — but the scale and the hazards are different.
Higher voltage. On a single-phase supply, the voltage between line and neutral is 230 V. On a three-phase supply, the voltage between any two lines is 400 V. A fault between phases is more dangerous than a fault on a single-phase circuit, and the test engineer must work with higher voltages during live testing.
More distribution. A small factory might have one main distribution board feeding four or five sub-distribution boards across different zones — production, office, warehouse, loading bay, welfare. Each board has its own circuits, its own protective devices, and its own earthing arrangement to verify. The engineer must trace the distribution from the intake right through to the final circuits.
Heavier cabling. Three-phase sub-mains are typically heavy SWA (steel wire armoured) cables run in trunking, on cable trays, or buried in floor screeds. Inspecting the condition of these cables, checking gland connections, and confirming the armour is correctly bonded to earth takes time and physical access.
Fixed machinery. Factories and workshops have three-phase machinery — lathes, CNC machines, compressors, welding sets, dust extraction, ovens — connected through isolators, contactors and sometimes star-delta starters. Each connection must be inspected. The engineer checks the condition of the flexible cable or conduit connection, the integrity of the isolator, and the earth continuity right through to the machine frame.
Higher fault currents. Three-phase supplies deliver higher prospective fault current than single-phase. The protective devices must be rated to safely break these higher currents. Part of the EICR is confirming that the measured prospective fault current at each board does not exceed the rated breaking capacity of the devices installed.
What Gets Inspected During a Three-Phase EICR
The inspection follows the same structure as any EICR but with more items to cover.
Intake and metering. The main cut-out, the meter, the service cable condition and the main protective devices. The engineer records the supply characteristics — three-phase, the earthing arrangement (usually TN-C-S or TN-S for industrial supplies), and the measured prospective fault current at the origin.
Main distribution board. Every circuit breaker, MCCB or fuse in the main board is inspected visually and checked for correct rating. The engineer verifies that circuits are properly labelled, that busbars show no signs of overheating, and that connections are tight. Thermal imaging can identify hot spots on loaded circuits.
Sub-distribution boards. Each sub-board receives the same treatment. In a large factory there may be six, eight or more sub-boards. Each must be opened, inspected, and tested. Circuit labelling is a persistent issue in industrial premises — boards that were labelled when installed but have had circuits added, removed or repurposed over the years.
Sub-mains and cable routes. The engineer inspects the cables running between boards — condition, routing, support, fire stopping through walls and floors, gland integrity, and armour bonding. SWA cable in a factory environment takes more abuse than domestic cable — forklift damage, chemical exposure, vibration, and heat from nearby processes.
Final circuits and equipment. Every socket circuit, lighting circuit, fixed machinery connection, and dedicated circuit is inspected and tested. This includes earth fault loop impedance testing at the furthest point of each circuit, insulation resistance testing on each circuit, and RCD testing where RCDs are installed.
Earthing and bonding. The main earthing terminal, the main protective bonding conductors to incoming services (gas, water, oil), supplementary bonding where required, and the earth continuity to every exposed conductive part. In an industrial environment, this includes machine frames, metallic ducting, cable trays, and structural steelwork if it forms part of the earth path.
How Long Does It Take?
The duration depends on the size of the installation.
A small workshop with one main board and two or three sub-boards — perhaps thirty to fifty circuits — typically takes a full day. An engineer arrives at 8 AM and finishes testing by 4 or 5 PM.
A medium-sized factory with five or six distribution boards and eighty to a hundred and twenty circuits takes one and a half to two days.
A large industrial unit with multiple zones, separate buildings, or high circuit counts can take three or more days. We usually survey large sites first to provide an accurate time estimate.
Downtime considerations. Some testing requires circuits to be de-energised — insulation resistance testing in particular. In a production environment, this can mean shutting down machinery for periods during the test. We work with factory managers to schedule dead testing during breaks, shift changes, or planned shutdowns. It is not always possible to test everything without some disruption, but with planning, the impact on production can be minimised.
Common Three-Phase EICR Failures
The issues that come up most often in Greater Manchester factories and workshops.
Missing or deteriorated bonding. Bonding conductors to incoming gas and water services get damaged during building works or removed during pipework alterations. Machine frames that should be bonded to earth via the supply cable armour have corroded gland connections that break the earth path.
Overloaded circuits. Production changes over the years — new machinery added, circuits extended, sockets doubled up — without upgrading the protective devices or the cable. An MCB rated at 32 A protecting a cable that is now feeding more load than it was designed for.
Deteriorated SWA cable. Steel wire armoured cable in factory environments gets cut, crushed, exposed to chemicals, or run through areas where it overheats. The PVC outer sheath degrades, the steel armour corrodes, and the insulation resistance drops.
Circuit labelling. Distribution boards with no labels, wrong labels, or labels that describe circuits that no longer exist. This is a C3 observation, but it makes the installation harder to manage safely and we flag it on every inspection.
Absent RCD protection. Many older industrial installations pre-date the requirement for RCD protection on socket circuits. The sockets work, but there is no 30 mA RCD protecting the person who plugs in a portable tool with a damaged cable.
What It Costs
Three-phase EICR costs in Greater Manchester vary with the size and complexity of the installation.
- Small workshop (1 main board, 2-3 sub-boards, 30-50 circuits): £600 to £900
- Medium factory (1 main board, 4-6 sub-boards, 80-120 circuits): £1,000 to £1,600
- Large industrial unit (multiple zones, 6+ boards, 150+ circuits): £1,500 to £2,500+
For multi-unit sites or landlords with several industrial properties, we offer volume pricing. The survey is free and the quote is fixed — no open-ended day rates.
How to Prepare Your Premises
A small amount of preparation saves significant time on the day.
Provide the previous EICR and any electrical drawings. If you have the last inspection report and any as-built drawings or schematic diagrams, give them to the engineer on arrival. They help map the installation quickly.
Ensure all distribution boards are accessible. Clear any stock, equipment or obstructions from in front of every distribution board. The engineer needs full access to open covers, inspect terminals, and connect test equipment. Boards behind racking or blocked by pallets add hours to the inspection.
Label your circuits if you can. If you know what each circuit feeds, even rough labels are helpful. If you do not know, the engineer will work it out, but it takes longer.
Plan for power interruptions. Discuss with the engineer in advance which circuits will need to be de-energised and when. If you have production schedules, share them. We will work around your operations as far as possible.
Ensure someone with authority is on site. The engineer may need to access locked areas, switch off machinery, or make decisions about scheduling. Having a responsible person available throughout the day keeps the inspection moving.
Book Your Three-Phase EICR
Call 0161 706 1360 to arrange a free survey of your factory, workshop or industrial unit. We will visit, assess the installation, and provide a fixed-price quote for the EICR. Manchester Compliance covers all of Greater Manchester — Salford, Stockport, Oldham, Tameside, Rochdale, Bolton, Bury, Trafford, Wigan and Manchester city centre.
We are NICEIC-approved contractors with extensive experience in industrial and commercial electrical testing.
Email: hello@manchestercompliance.co.uk Phone: 0161 706 1360 Address: 25 Holden Clough Drive, Ashton-under-Lyne, OL7 9TH