Every UPS Plug and Connector Type, With Amps and Voltage Charts

Buying a UPS is easy. Getting it to physically connect is where people get stuck. A 3000VA rack unit arrives with a plug that does not fit the outlet in the rack. A server has a power cord that will not enter the UPS. A replacement UPS looks identical to the old one but has a different input plug. None of this lives in one place, so people guess, and guessing with power gets expensive.

This is the single reference. Every connector you will meet on a UPS, what it looks like, what it is rated for, what circuit it needs, and which UPS sizes use it. We install and power server rooms across the GTA, so this is the same guidance we give clients before they order.

The nine connectors that cover almost every UPS installation.

The Quick Answer

UPS plugs fall into three families:

• NEMA plugs are used in North America. Straight blade types like 5-15P and 5-20P, plus twist lock types like L5-30P and L6-30P.
• IEC 60320 connectors are the small computer-style connectors used worldwide, mainly C13/C14 and C19/C20.
• IEC 60309 connectors are the round, colour-coded industrial plugs used on large and three-phase UPS.

Above roughly 10 kVA, most UPS units drop plugs entirely and are hardwired to a terminal block by an electrician.

First, the Three Connection Points

Every UPS has three separate connection areas. People mix them up constantly, so start here. The input side feeds power in, the output side is where your gear plugs in, and the data side is what makes the unit manageable.

Part 1: UPS Input Plugs, the Wall Side

The input plug tells you exactly what circuit your electrician needs to provide. Match this first, because you cannot change it without changing the UPS. Short descriptions below, full ratings in the comparison table further down.

NEMA 5-15P. The everyday North American plug. Two flat blades and a round ground pin. 15A at 125V, continuous limit 1,440VA. Fits both 15A and 20A outlets. Found on most UPS from 350VA to 1500VA.

NEMA 5-20P. Same as the 5-15P but the neutral blade is turned sideways. 20A at 125V, continuous limit 1,920VA. It will not fit a plain 15A outlet, and that is deliberate. You need a 5-20R outlet, not an adapter. Common on 1500VA to 2200VA units.

NEMA L5-30P. A round twist lock plug. Push in and twist a quarter turn to lock. 30A at 125V, continuous limit 2,880VA. Used on 2200VA to 3000VA rack UPS and external battery packs. It locks because a rack cord that gets bumped should never drop the load.

NEMA L6-20P and L6-30P. Same round locking body as the L5, but no neutral, just two hot legs and a ground, and the blade pattern differs so they will not cross-connect. Run at 208V or 240V. This is the standard for modern data centre rack UPS from 2 kVA to 5 kVA. Running at 208V roughly doubles the power available on the same amperage.

NEMA L14-30P and L21-30P. Larger locking plugs for split-phase and three-phase feeds. The L21-30P (five blades, 120/208V three phase) is the common input on 8 kVA to 10 kVA three-phase rack UPS in North America.

IEC C14 and C20 inlets. Recessed chassis inlets rather than cord-end plugs. A C14 caps input at 15A and is found on compact rack UPS up to about 1500VA. A C20 is larger, handles 16A to 20A, and appears on 208V and 230V rack UPS in the 2 kVA to 3 kVA range.

Hardwired terminal block. A metal cover plate with brass lugs labelled L1, L2, L3, N and ground. Standard on everything above about 6 kVA and effectively all UPS above 10 kVA. Needs a licensed electrician, a local disconnect, correctly sized conductors and inspection.

Twist lock plugs look alike from a distance. The blade pattern is what makes them incompatible.

Part 2: UPS Output Receptacles, the Equipment Side

Output sockets determine what you can plug in and how many devices you can protect.

IEC C13. The female connector on a standard computer power cord, and the single most common connector in any rack. Small rectangle, two bevelled top corners. 10A internationally, 15A in North America, though most vendors derate their outlets to 10A or 12A. Plugs into the C14 inlet on servers, switches and PDUs.

IEC C19. Much larger and wider than a C13, closer to a letterbox slot. 16A internationally, 20A in North America. Plugs into the C20 inlets on blade chassis, storage arrays and large PDUs. Found on rack UPS from about 2 kVA up, usually one or two C19 outlets alongside a bank of C13s.

C15 and C21. Look almost identical to C13 and C19 but rated for higher temperatures. A C15 (notch in the bottom) fits a standard C14 inlet, so a C15 cord can replace a C13 cord. The reverse is not true. Common on Cisco gear and equipment that runs hot.

NEMA 5-15R and 5-20R. Standard North American outlets built into the chassis, on tower and 120V rack UPS. Watch for this: on consumer models, some outlets are battery-backed and some are surge-only. Plugging a server into the surge-only bank means no runtime at all during an outage. Check the labels before you cable.

Twist lock and hardwired outputs. On a UPS, locking outputs usually feed a rack PDU rather than individual devices. One locking output feeding a PDU with twenty C13 sockets is the standard rack design. Large UPS terminate into a distribution panel instead of sockets.

C13 vs C19, the simple test: a C13 is small and roughly square with angled top corners. A C19 is wide, flat and rounded. They do not interchange in either direction. If you are forcing it, it is the wrong one.

Part 3: International Plug Types

Outside North America, a UPS ships with a different cord for each region. The unit is often the same, only the cord changes.

Part 4: Industrial and Three-Phase Connectors

Once a UPS passes roughly 5 kVA, standard plugs run out of headroom and industrial connectors take over. The main one is IEC 60309, also called CEE Form, Commando or pin and sleeve. Three things identify it: colour tells you the voltage band, pin count tells you the phase, and the keyway position physically prevents wrong connections.

Pin count. 3-pin (2P+E) is single phase. 4-pin (3P+E) is three phase without neutral. 5-pin (3P+N+E) is three phase with neutral, the standard for three-phase UPS input. Common sizes are 16A, 32A, 63A and 125A. A blue 32A 2P+E is the most common single-phase UPS feed in Europe; a red 32A 3P+N+E is the most common three-phase feed.

Battery connectors. Between a UPS and its external battery cabinet you will find Anderson SB series connectors (SB50, SB120, SB175). The housing colours are keyed so a 24V pack cannot be connected to a 48V system. Never file down or force a mismatched colour, because that keying exists to prevent a battery fire. Very large battery cabinets skip connectors entirely and bolt to busbars with ring terminals, torqued to spec.

Colour tells you the voltage. Pin count tells you the phase. The keyway prevents mistakes.

Part 5: Data and Communication Ports

When people ask about UPS connection types, they sometimes mean these, not the power plugs. This is what turns a UPS from a battery into a managed device.

Buying tip: if a UPS will protect more than one server, budget for a network management card up front. A single USB cable can only shut down one machine cleanly.

Table 1: UPS Input Plugs Compared

Table 2: The IEC 60320 Family at a Glance

Interchange rules worth memorising: C15 fits a C14 inlet, but C13 does not fit a C16 inlet. C13 and C19 never interchange. C21 fits a C20 inlet, but C19 does not fit a C22 inlet.

Table 3: Circuit to Maximum UPS Size

Use this to check whether the circuit you have can actually feed the UPS you want. The continuous figure already applies the 80 percent rule, which is what you should design to.

Three-phase VA is volts × amps × 1.732. For 400V at 32A that is 400 × 32 × 1.732 = 22,170VA.

How to Pick the Right Connector

Work through these in order. Do not skip step one.

1. Start with the circuit you actually have. Look at your breaker panel, not the wall. A 20A outlet fed by a 15A breaker is still a 15A circuit.
2. Add up your real load in watts. Use nameplate watts, or better, measure with a clamp meter or metered PDU. Nameplate figures are usually generous.
3. Add 25 percent headroom. Loads grow. A UPS running at 90 percent capacity has almost no runtime and no room for another server.
4. Choose the voltage. Above about 2000VA, pick 208V or 230V if you can. More power per amp and slightly better efficiency.
5. Match the input plug to the circuit. Use Table 3. If the UPS needs a circuit you do not have, the cost of that circuit is part of the UPS cost.
6. Check the output sockets against your gear. Count your C13, C19 and NEMA needs. Short on outlets? Plan a rack PDU on the UPS output, not a power strip.
7. Decide on monitoring before you order. More than one server means you want a network management card, and those often ship separately.

Cords, Adapters and What Is Safe

• Jumper cords are fine. A C14 to C13 jumper from a UPS or PDU to a server is standard and correct.
• Stepping down is usually acceptable. A C20 to C13 cord moves power from a higher-rated source to a lower-rated device. The device’s own protection handles the rest.
• Stepping up is not. An adapter that lets a 20A plug enter a 15A outlet defeats the physical keying that stops you overloading the circuit. Do not use these.
• Never remove a ground pin. Cutting or filing the ground pin removes the fault path that keeps the chassis from going live. There is no situation where this is acceptable.
• Never daisy chain power strips. A strip into a strip into the UPS is a fire code violation in most jurisdictions and a real fire risk. Install a rack PDU instead.
• Watch the cord gauge. For 15A use 14 AWG, for 20A use 12 AWG. A thin cord is a heating problem regardless of the plug rating.
• Locking IEC cords exist. C13 and C19 cords with a built-in latch prevent the most common outage cause of all, someone bumping a cord loose. They are cheap and worth it.

Common Mistakes

• Assuming VA equals watts. A 1500VA UPS typically delivers 900 to 1000 watts. Power factor is the difference. Size on watts.
• Plugging into the surge-only bank. On consumer UPS, half the outlets often have no battery backup. Read the labels.
• Ignoring the input plug when replacing a UPS. Two units with the same VA rating can have different input plugs. Check before the old one leaves the rack.
• Feeding a laser printer from a UPS. Printers draw huge surges when the fuser heats, trip overload protection and shorten battery life. Use a surge-only outlet.
• Forgetting the maintenance bypass. On a hardwired UPS, without a bypass panel you have to power down the entire load to service the unit. Design it in on day one.
• Overlooking the EPO wiring. In many data centre and lab installs an EPO circuit is required by code. Find out before the inspection, not after.

One feed from the UPS to a PDU, then individual cords to each device. Never chain power strips.

Last reviewed August 2026. Ratings follow NEMA, IEC 60320 and IEC 60309 standards. Always confirm against your equipment nameplate and local electrical code. Installation of new circuits and hardwired equipment should be carried out by a licensed electrician.