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The power cord is the one component that every piece of electrical equipment needs and almost nobody specs carefully until the last minute. Then someone realizes the cord in the stockroom has the wrong plug for the destination country, or the wire gauge is too light for the load, or the cord is two feet too short to reach the outlet in a standard rack layout. This guide walks through the handful of decisions that get the cord right the first time, so the cord is not the reason a shipment gets held at customs or a product fails a site acceptance test.
How to Choose the Right Power Cord: Plug Type, Wire Gauge, and Length
Start With the Plug: NEMA, IEC, or Country-Specific?
The plug on the wall end of the cord determines whether the equipment can be plugged in at all. Get this wrong and the most perfectly spec’d cord in the world is useless at the destination site.
NEMA Plugs: The North American Standard
NEMA 5-15P is the standard three-prong grounded plug for 120 V, 15 A circuits in North America. It is the plug on nearly every consumer and commercial power cord sold in the US and Canada. NEMA 5-20P is the 20 A version with one horizontal blade, used on equipment that draws more than 15 A or when the circuit is a dedicated 20 A branch. For 240 V equipment in North America, NEMA 6-15P and 6-20P are the standard configurations, with horizontal and vertical blade orientations that prevent plugging 240 V equipment into a 120 V outlet. If the equipment ships to North America and draws 15 A or less at 120 V, NEMA 5-15P is the default answer. Anything else is application-specific and needs to be verified against the site power available at the destination.
International Plugs: One Cord Per Market
Equipment that ships internationally needs the plug that matches the destination country standard. CEE 7/7 Schuko plugs cover most of continental Europe. BS 1363 fused plugs are required for the United Kingdom, Ireland, and several Commonwealth countries. AS/NZS 3112 plugs serve Australia and New Zealand. GB 2099 plugs serve China. Each market has its own plug geometry and its own safety requirements, such as the mandatory fuse in UK plugs or the recessed socket requirement in French and Belgian installations. The common approach for global equipment is to specify the IEC inlet on the equipment side. typically C14 for up to 10 A or C20 for up to 16 A. and supply the appropriate country-specific cord set with each shipment. The equipment design stays the same. Only the cord changes.
Application detail — Lanz Manufacturing
Wire Gauge: When 18 AWG Is Enough and When It Is Not
Wire gauge is the single most important number on a power cord specification after the plug type. Too thin and the cord overheats. Too thick and it is stiff, expensive, and hard to manage in tight spaces.
The Relationship Between Gauge, Current, and Length
American Wire Gauge runs inversely to conductor size: 18 AWG is thinner than 16 AWG, which is thinner than 14 AWG. For power cords, 18 AWG is the standard for equipment drawing up to 10 A at lengths up to about 6 feet. At 10 A through 6 feet of 18 AWG copper, voltage drop is under 1 volt, which is acceptable for virtually all equipment. Push the cord length to 15 feet at 10 A and the voltage drop through 18 AWG climbs past 2 volts. That may still be acceptable, but it depends on the equipment input voltage tolerance. For 15 A loads, 16 AWG is the standard minimum. For 20 A loads, 14 AWG or 12 AWG depending on length. The gauge requirement comes from two places: the ampacity rating of the conductor for safety and the voltage drop calculation for equipment performance. Both must be satisfied. The more restrictive one determines the final gauge.
Reading the Cord Markings for Gauge and Type
Every listed power cord carries printed markings along its length that identify the wire gauge, number of conductors, and jacket type. A marking like “3×18 AWG SJT” means three conductors (line, neutral, ground) of 18 AWG wire with an SJT-rated thermoplastic jacket. “3×14 AWG SJT” means the same jacket type with heavier 14 AWG conductors. The jacket type designation. SJT, SVT, SJ, SJOOW. tells you the voltage rating, temperature rating, and whether the jacket is thermoplastic or rubber. These markings are standardized across North American cord manufacturers. If you need to verify what cord is attached to a piece of equipment, read the printed text on the jacket. It is the definitive specification.
Cord Length: Short Enough to Avoid Coils, Long Enough to Reach
Cord length seems like the simplest decision and causes the most field complaints. Too short and the equipment cannot reach the outlet. Too long and the excess cord ends up coiled behind the rack, creating a heat trap and a trip hazard.
Standard Lengths and When to Deviate
The standard lengths for equipment power cords are 1.8 meters (6 feet) and 2.5 meters (8 feet). These cover the vast majority of installations where the equipment sits within a few feet of a wall outlet or a rack-mount PDU. A server in a rack typically needs a 2 to 3 foot cord because the PDU is mounted in the same rack. A piece of test equipment on a lab bench may need a 10 foot cord to reach the nearest outlet. Specifying the right length starts with knowing where the equipment will sit relative to the power source. For data center equipment, measure the distance from the equipment inlet to the nearest PDU outlet along the cable management path, not in a straight line. Cables route through arms, trays, and vertical managers. The actual path length is always longer than the straight line.
The Problem With Excess Cord
Excess cord coiled behind or under equipment creates three problems. First, a coiled cord carrying near its rated current generates more heat than the same cord laid straight because the coils restrict air cooling around the jacket. Second, a coiled cord on the floor becomes a trip hazard in high-traffic areas. Third, in data center cold aisles, a pile of excess cord blocks airflow under raised floor tiles. The standard recommendation is to specify the shortest cord that reaches the outlet with enough slack to allow equipment to be pulled forward for service without unplugging. For rack-mount equipment, that typically means 2 to 4 feet. For bench-top equipment, 6 to 8 feet. Anything longer should have a specific reason.
Jacket Material: PVC, Rubber, or Halogen-Free?
The cord jacket is the outermost layer of insulation. It takes the abuse: abrasion from being dragged across floors, chemical exposure in industrial environments, and heat from being run near hot equipment. The right jacket material keeps the conductors safe. The wrong one cracks, melts, or burns.
PVC (SJT, SVT): The General Purpose Standard
PVC-jacketed cords are the most common and the least expensive. SJT-rated cord is suitable for indoor use at voltages up to 300 V and temperatures up to 60 degrees Celsius for continuous use. SVT is a lighter-duty version with a thinner jacket, used on vacuum cleaners, office equipment, and consumer electronics. PVC works well in clean, dry, temperature-controlled environments. It does not hold up well against oil, solvents, or prolonged outdoor exposure. If the cord will be used in a machine shop, a commercial kitchen, or outdoors, PVC is not the right choice.
Rubber (SJOOW, SOOW) and Halogen-Free Options
Rubber-jacketed cords handle harsh environments. SJOOW and SOOW cords use thermoset rubber jackets that resist oil, water, chemicals, and abrasion. They stay flexible in cold temperatures where PVC stiffens and cracks. Rubber cords are the standard for construction sites, outdoor events, industrial machinery, and any application where the cord gets dragged across rough surfaces. Halogen-free cords are a separate category driven by safety regulations in specific markets and applications. Halogen-free jackets do not release corrosive hydrogen chloride gas when burned, which matters in confined spaces like data centers, tunnels, and mass transit vehicles where smoke toxicity and equipment corrosion from fire are design concerns. Halogen-free cords cost more than PVC and are specified when the end application or local building code requires them.
Connector End: C13, C19, or Something Else?
The connector on the equipment end of the cord must match the inlet on the equipment. The IEC 60320 standard defines the common combinations, and mixing them up means the cord physically will not plug in.
C13/C14: The Universal Standard for Up to 10 A
The C13 connector on the cord end mates with the C14 inlet on the equipment. This is by far the most common power cord configuration worldwide. Rated for up to 10 A at 250 VAC, the C13/C14 combination appears on desktop computers, monitors, printers, network switches, laboratory instruments, and most commercial electronic equipment. If the equipment has a C14 inlet and draws 10 A or less, a C13 cord is the standard answer. The C13 connector has a distinctive trapezoidal shape with three rectangular slots. A C15 connector looks similar but has a notch cut out to handle higher temperature applications up to 120 degrees Celsius. C15 mates with C16 inlets on equipment that runs hot, such as servers with high-density power supplies and some networking gear.
C19/C20: Heavy Duty for Up to 16 A
The C19 connector on the cord end mates with the C20 inlet on the equipment. It is larger than C13, with rectangular pins oriented horizontally rather than in a trapezoidal arrangement. Rated for up to 16 A at 250 VAC, C19/C20 cords power servers with high-wattage power supplies, blade chassis, large UPS units, and industrial equipment that draws more than 10 A. A C19 connector will not fit into a C14 inlet, which is intentional. The physical incompatibility prevents someone from plugging a 16 A piece of equipment into a 10 A cord. If the equipment inlet is C20, the cord connector must be C19. No adapter, no workaround, no exception.
LANZ Power Cord Options for Your Equipment
LANZ Electronics manufactures power cords in standard and custom configurations for commercial and industrial equipment. The product line covers NEMA, IEC, and international plug types across multiple wire gauges, lengths, and jacket materials.
Standard Cord Sets
LANZ power cords are available with NEMA 5-15P, CEE 7/7, BS 1363, and other country-specific plugs on the wall end and C13, C15, or C19 connectors on the equipment end. Standard lengths from 1 to 3 meters cover most equipment applications. Custom lengths, jacket materials, and labeling are available for OEM projects with defined volume requirements.
Frequently Asked Questions
What is the most common power cord type in North America?
NEMA 5-15P to IEC C13 is the most common power cord configuration in North America. The NEMA 5-15P plug connects to standard 120 V, 15 A wall outlets, and the C13 connector plugs into the C14 inlet on most electronic equipment. This cord powers desktop computers, monitors, printers, network switches, and the majority of commercial and consumer electronics sold in the US and Canada.
How do I know what wire gauge I need?
The wire gauge depends on the equipment current draw and the cord length. For loads up to 10 A at lengths up to 6 feet, 18 AWG is standard. For 10 to 15 A loads or longer runs, 16 AWG is the minimum. For 15 to 20 A loads, use 14 AWG or heavier. Always check the cord ampacity rating against the equipment nameplate current and apply the 80 percent derating rule for continuous loads: a cord rated for 10 A should not carry more than 8 A continuously. The printed markings on the cord jacket confirm the actual gauge.
Can I use a longer cord than the equipment came with?
Yes, within limits. A longer cord increases voltage drop, which can cause equipment to malfunction or draw higher current to compensate. For every additional 6 feet of 18 AWG cord at 10 A, voltage drop increases by roughly 0.8 volts. Most equipment tolerates a few volts of drop, but check the input voltage specification. The cord ampacity rating also applies regardless of length: a longer cord at the same current does not need a heavier gauge for ampacity reasons, but it does for voltage drop reasons. When in doubt, go up one gauge size for cords longer than 15 feet.
What is the difference between SJT and SVT cord jackets?
SJT is a heavier-duty thermoplastic jacket rated for 300 V and 60 degrees Celsius. It is the standard jacket for equipment power cords in office and light industrial environments. SVT is a lighter-duty version with a thinner jacket, rated for the same voltage and temperature but less resistant to abrasion and cut-through. SVT cords are used on vacuum cleaners, small appliances, and consumer electronics where the cord stays indoors and does not see rough handling. For any equipment that ships to an industrial environment, SJT is the safer default.
Talk with Lanz Manufacturing about specifications, samples, and production support.
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