Partitioned Terminal Strips: Specifications, Performance, Types, Selection & Applications

Partitioned terminal strips are modular rail-mounted connection systems in which each individual clamping point is separated by an integral insulating partition rising above the contact plane.
The partition physically blocks accidental contact between adjacent poles, extends the creepage and clearance distance, and prevents arc flash from propagating across interconnected circuits during short-circuit events.
Each strip consists of a glass-fiber-reinforced polyamide housing, a nickel-plated brass current bar, and captive screw or spring clamp termination elements that accept solid, stranded, or ferruled conductors.
Working on the same principle as standard terminal blocks, the partitioned version adds a raised dielectric wall between every pole, allowing different voltage groups to coexist safely on a single DIN rail profile.
Partitioned strips are widely deployed in motor control centers, programmable logic controller cabinets, industrial instrumentation loops, and power distribution boards where mixed voltage levels exist side by side.
Their modular construction supports secure snap-on mounting onto 35 mm DIN rails, simplifying panel wiring, circuit identification, and field replacement without dismantling adjacent poles.

The table below summarizes the standard specification envelope for industrial-grade partitioned terminal strips, covering electrical, mechanical, and physical parameters.
Actual values vary by manufacturer and IEC 60947-7-1 compliance level, so confirm datasheet ratings before design release.
Partition geometry directly governs the maximum rated voltage, so never substitute a visually similar strip without checking its clearance distances.

Thermal, Mechanical, and UV Resistance Partitioned terminal strips are predominantly molded from glass-fiber-reinforced polyamide 66, which provides high mechanical strength, dimensional stability, and self-extinguishing behavior under elevated thermal loads.
The housing formulation includes UV stabilizers and halogen-free flame retardants, permitting outdoor cabinet installations and low-smoke, zero-halogen compliance in marine, offshore, and tunnel ventilation systems.
Standard strips operate continuously between -40 °C and +120 °C, with special high-temperature versions available for operation up to +150 °C.
Corrosion and Chemical Resistance The nickel-plated brass current bar resists oxidation and electrical pitting, maintaining stable contact resistance across repeated clamping cycles in humid or chemically aggressive factory atmospheres.
Exposure to mineral oils, dilute acids, and common industrial cleaning agents has limited effect on polyamide housings, although prolonged contact with strong solvents should be avoided.
The raised partition inherently resists dust bridging and creepage contamination because it prolongs the pollution degree path between live parts, which is critical in cement plants, textile mills, food processing lines, and wastewater facilities.

The comparison table below presents common partitioned terminal strip versions, distinguishing clamping technology, electrical capacity, and intended duty.
Selection between these versions depends on the wiring environment, labor skill level, and the mechanical stress profile of the final assembly.

Core System Functions Partitioned terminal strips serve three critical functions within an electrical installation: physical isolation, mechanical termination, and electrical distribution.
The partition wall prevents tools, stripped wire ends, or dropped hardware from bridging adjacent live poles, directly reducing the probability of phase-to-phase short circuits during maintenance.
Individual poles can be bridged with insulated jumper bars to form common neutral or grounding buses, while the partition retains clear visual separation between circuit groups for documentation and troubleshooting.
Typical Industrial Applications In industrial automation, partitioned strips marshal field sensor signals into programmable logic controller input modules, isolating 24 V DC loops from 230 V AC power circuits.
Motor control centers use partitioned power strips to terminate feeder cables at distribution points, with each partition corresponding to one branch circuit for straightforward fault localization.
Railway signaling cabinets rely on partitioned strips to separate interlocking voltages, and solar combiner boxes use them to isolate individual string circuits before the inverter.
Additional deployments include elevator control panels, packaging machinery, HVAC plant rooms, water treatment skids, and machine tool electrical enclosures, where mixed-voltage wiring rules demand enforced segregation.

Selection Criteria for Engineering Specifications Begin selection by comparing the system nominal voltage and prospective short-circuit current against the strip's rated insulation voltage and rated current; the partition height must exceed the minimum creepage distance required by IEC 60947-7-1 for the prevailing pollution degree.
Choose screw clamps for high-current power circuits and spring clamps for signal wiring, ensuring the conductor cross-section matches the clamping range without reduction sleeves unless ferrules are specified.
Installation and Torque Procedure During installation, snap the strip onto a 35 mm DIN rail and verify firm engagement at both end brackets; vertical mounting is preferred to prevent dust settling on partition ledges.
Strip insulation to the manufacturer-specified length, typically 8 to 13 mm depending on clamp type, and torque screw clamps to the recommended value, commonly 0.5 to 0.8 N·m, to avoid conductor deformation and contact overheating.
Never install partitioned strips in cramped orientations that force wires upward against the partition edge, and maintain a minimum clearance zone above the barriers for cable entry tools and test probes.
Inspection and Maintenance Routines Use ferrules for stranded conductors in spring-clamp versions to prevent strand fraying, and always insert conductors until they bottom out inside the clamping cage.
Periodic inspection should verify clamp tightness and check for carbon tracking on partition surfaces; replace stripped or cracked barriers immediately, because the isolation function is the primary safety defense.

Q: What is the difference between a partitioned terminal strip and a standard terminal block?
A: A standard terminal block provides individual clamping points without raised separators, while a partitioned strip integrates insulating barriers above the contact plane between every pole. These partitions increase creepage distance, prevent accidental tool contact, and block arc propagation, making partitioned strips mandatory where mixed voltages share one mounting profile.
Q: Can partitioned terminal strips be used for both AC and DC circuits?
A: Yes. Partitioned strips are rated for AC and DC service up to 1000 V, depending on housing material and creepage configuration. DC circuits require more generous clearance because DC arcs do not self-extinguish at current zero. Always verify the manufacturer's DC voltage rating before grouping DC loads on one strip.
Q: What wire sizes does a typical partitioned terminal strip accept?
A: Common strips accept conductors from 0.5 mm² to 35 mm² in solid, stranded, or ferrule-terminated form. Smaller signal strips start at 0.14 mm², while high-current power strips reach 95 mm². Match the conductor cross-section to the clamping range and confirm the strip current rating matches the load.
Q: Are partitioned terminal strips suitable for high-vibration environments?
A: For vibrating equipment such as compressors, crushers, or engine-driven generators, choose spring-clamp or tension-clamp strips because spring pressure never loosens. Screw clamps with self-locking pressure plates remain acceptable when fitted with anti-vibration brackets and checked through regular torque audits.
Q: How do I calculate the required partition height for creepage protection?
A: Partition height depends on working voltage, pollution degree, and housing insulation group. Refer to IEC 60947-7-1: at 400 V AC with pollution degree 3, the partition must provide at least 6.3 mm creepage distance. Manufacturer datasheets list approved partition geometries for each rated voltage and current.
Q: Can partitioned strips be ganged or bridged to form common circuits?
A: Yes. Insulated jumper bars or bridge plugs connect adjacent poles to create common supply, neutral, or grounding bars while preserving the partition above. Use only manufacturer-approved bridging components rated for the strip current; field-fabricated wire jumpers compromise creepage protection and void approval.
Q: What is the maximum operating temperature for partitioned terminal strips?
A: Standard polyamide strips operate from -40 °C to +120 °C continuously, with short-term peaks up to +150 °C. Ceramic-bodied partitioned strips withstand temperatures above +200 °C and suit furnace control circuits. Derate current capacity above 85 °C ambient according to the manufacturer's curve.
Q: Do partitioned terminal strips require special tools for installation?
A: Standard strips require only a torque screwdriver and wire stripper. Spring-clamp versions accept push-in wiring without tools; tension-clamp versions need an operating screwdriver. DIN rail mounting uses the release lever or a screwdriver depending on the strip locking mechanism. Ferrule crimpers are recommended for stranded conductors.
Q: How do partitioned strips compare to disconnect terminal blocks?
A: A partitioned strip provides continuous circuit connection, while a disconnect terminal block contains a knife switch or plug for opening the circuit. Partitioned strips emphasize physical isolation between adjacent poles, not switching functionality. In control panels, both types often coexist to satisfy isolation and interruption requirements.
Q: What maintenance is required for partitioned terminal strips?
A: Inspect screw torque, conductor insulation integrity, and partition surfaces for carbon tracking or cracks. Remove dust with dry compressed air and replace any damaged strip. Thermographic scanning of energized panels reveals loose internal connections before they cause failures.
Q: How should I label partitioned terminal strips in a control cabinet?
A: Use manufacturer marker tags or laser-printed snap-on labels positioned on the partition or front marker slot. Follow the cabinet schematic numbering convention and distinguish voltage groups with color-coded markers so circuit identification remains visible after wiring.

Partitioned terminal strips deliver essential circuit segregation, mechanical termination, and safe electrical distribution inside modern industrial control cabinets.
Their integrated insulating partitions prevent arc bridging, extend creepage distances, and simplify mixed-voltage wiring across automation, power, and process installations.
Correct selection requires matching voltage, current, wire range, environmental temperature, and clamp technology to the application, while disciplined installation and periodic torque inspection preserve long-term reliability.
Specify partitioned strips to reduce fault risk, accelerate troubleshooting, and comply with IEC 60947-7-1 isolation requirements.