P-Lock, S-Lock, D-Lock & P-Lite Guide

The four systems, and where each locks

SSEMCO makes four locking systems for IEC 60320 cords, and they lock at different ends. P-Lock and P-Lite lock the plug into the PDU outlet — and only into an outlet built for it. S-Lock locks the connector onto the equipment inlet, and any standard inlet will do. D-Lock puts one of each on the same cord. Every figure and every compatibility claim below comes from the maker's or the PDU maker's own publication; the sources are listed at the end.

P-Lock

The most widely deployed locking plug in the rack.

How it works: two spring tabs — the P-shaped clips — on either side of the plug head click into the latch slots of a P-Lock-ready outlet as the plug seats. Pull on the cord and the tabs bear on the outlet, not the pins. Pinch both tabs and pull to release. On a plain outlet with no latch slots the plug seats and carries current like any C14 or C20, but it does not lock; SSEMCO calls that "backward compatible with any standard C13 outlet". The connector at the equipment end is a standard C13, C15 or C19 and locks nothing.

Withdrawal force: up to 120 N (about 27 lbf), SSEMCO's published figure.

Best for: the PDU end must not come loose and the PDU is one of the makers above. If the PDU has plain outlets, P-Lock only seats — choose an equipment-side lock (S-Lock, A-Lock) or a cord that locks both ends on plain hardware (Z-Lock+) instead. P-Lock cords →

P-Lite

P-Lock for high-density PDUs.

How it works: the P-Lock latch on one side of a low-profile C14 plug head whose other side is recessed, so a fingertip reaches the single tab between neighbours on a fully loaded PDU. Press the tab into the recess and pull to release. Same P-Lock-ready outlets as P-Lock; Eaton sells the same idea for its G4 PDUs as P-Lock Lite.

Withdrawal force: the same latch as P-Lock; SSEMCO publishes no separate figure for P-Lite.

Best for: outlets on a pitch so tight that a full-size P-Lock head blocks its neighbour. P-Lite cords →

S-Lock

The rotary lock for the equipment end.

How it works: SSEMCO's second-generation rotary securing system. Push the connector onto the inlet and turn the grey collar a quarter turn; internal pins pinch the inlet's pins. Turn the collar back and pull to release — one hand, no clearance needed beside the connector, which is why it suits inlets packed shoulder to shoulder. It fits any standard C14 or C20 inlet; nothing on the PDU side matters, because the plug end is a standard, non-locking plug. It is not Scolmore's IEC Lock (a C13 with a red top tab that grips the earth pin): a different maker and a different mechanism.

Withdrawal force: SSEMCO publishes none for S-Lock, so this guide prints none.

Best for: the equipment must not come unplugged, the PDU is anything at all, and a twist release is preferred to squeeze tabs. S-Lock cords →

D-Lock (Dual-Lock)

Both ends locked.

How it works: a P-Lock plug for the PDU and an S-Lock connector for the equipment, on one cord. Pinch the plug tabs at the PDU; turn the collar back at the equipment — two different motions on purpose, so freeing one end does not free the other by reflex. The plug end needs the same P-Lock-ready outlets as P-Lock; on a plain outlet it seats without locking and the cord behaves as an S-Lock.

Withdrawal force: up to 120 N at the P-Lock end (SSEMCO); none published for the S-Lock end.

Best for: racks where neither end may come loose and the PDU has P-Lock-ready outlets. For plain PDU outlets at both ends the answer is Zonit's Z-Lock+, which we build in Connecticut. Dual-Lock cords →

Which PDUs take the P-Lock plug

The plug-side systems — P-Lock, P-Lite and the plug end of D-Lock — lock only into an outlet with latch slots for the tabs. PDU makers call that outlet lockable, lock-ready, SecureLock-ready, P-Lock compatible or high-retention. These makers say so in their own publications:

Reported, not verified: Knürr and Bachmann PDUs are named as P-Lock compatible in reseller copy (StayOnline, Signal+Power) but not by the PDU maker or by us. Send us the model before ordering in volume.

What only seats

• APC / Schneider Electric. The locking outlets on AP8000-series Rack PDU 2G units are Schurter V-Lock, not P-Lock: a P-Lock plug seats there but has nothing to catch. A-Lock is not an APC system — it is the universal equipment-side connector and has no bearing on the PDU outlet. APC UPS and PDUs with plain C13 / C19 outlets take a standard plug that does not lock.
• Plain C13 / C19 outlets on any PDU, power strip or UPS, and outlets that lock a standard plug from the outlet side (Vertiv Geist U-Lock, Server Technology RamLock, Chatsworth QuadLock, Legrand's locking outlets): P-Lock seats and works but does not lock. Put the lock at the equipment end (S-Lock, A-Lock, IEC Lock), or use a cord that locks at both ends on plain hardware (Z-Lock+).
• Equipment inlets. S-Lock and the S-Lock end of D-Lock lock onto any standard C14 or C20 inlet, on any equipment — the one place "universal" is the right word.

Every mechanism we sell, against every outlet and inlet type, with its sources: the compatibility table on lockingpowercables.com.

Sources

1. SSEMCO — P-Lock C14 / C13 power cord: withdrawing force up to 120 N; mates SSEMCO R013SN / R013GX outlets; backward compatible with standard C13 outlets.
2. SSEMCO — S-Lock C14 / C13 power cord: second-generation rotary securing system, fits any standard C14 inlet, 10 / 13 / 15 A.
3. SSEMCO — locking solution products: P-Lock, P-Lite, S-Lock, D-Lock.
4. Eaton — Tripp Lite series P-Lock power cords brochure: P-Lock C13 / C19 / C39 outlets on G4 PDUs; the tabs click into a compatible P-Lock outlet.
5. P-Lock datasheet hosted by Server Technology: P-shaped clips, audible click, lockable and HDOT PDUs.
6. Raritan — SecureLock IEC power cables datasheet: latch slots inside every PX C13 / C19 outlet; C14 to C15 cords "with P-Lock".
7. Vertiv — Combination Outlet for Geist rack PDUs (2020): high-retention, P-Lock compatible.
8. Cables Plus USA — P-Lock locking power cables: receptacles found on ServerTech, Raritan and GELU PDUs.
9. Schurter — V-Lock connectors: latches into the notched inlet or outlet; pull-out force at least 200 N.
10. lockingpowercables.com — the compatibility table: every mechanism against every outlet and inlet type, with sources.

Checked against these sources on September 21, 2026. If your PDU is not named, send us the model and we will check the outlet before you order.