WHAT IS AN L-823 CONNECTOR?
The L-823 connector is a specialised airport-lighting plug or receptacle cable connector. It makes reliable electrical connections in AGL systems without ordinary open terminals at the field interface.
It is used with underground airport-lighting power cables, isolation-transformer leads, light-fixture leads, and primary and secondary circuit connections. The current specification is FAA AC 150/5345-26E (16 December 2021), which replaced -26D.
In one line
- L-823 = standardised AGL plug / receptacle connection system
CCR │ primary AGL cable ▼ L-823 connection │ ▼ Isolation transformer │ ▼ L-823 / secondary connection │ ▼ AGL light fixture
WHY THE CONNECTOR MATTERS
A connector must do far more than "make contact". It must provide:
- Electrical continuity
- Electrical insulation
- Mechanical strength
- Watertight sealing
- Environmental resistance
- Reliable repeated mating where applicable
The specification requires a watertight seal on the mated connector and defines electrical, mechanical and environmental performance. A connector is one of the critical interfaces between the CCR, cable, transformer and fixture.
TYPE, CLASS AND STYLE
AC 150/5345-26E classifies connectors by Type, Class and Style. It defines two types, two classes, and six plug styles plus six receptacle styles.
L-823 ├── TYPE : Type I / Type II = electrical classification ├── CLASS : Class A / Class B = how it is attached └── STYLE : Plug 1–6 / Receptacle 7–12 = physical configuration
Three-part memory
- TYPE: what electrical category? (I or II)
- CLASS: how is it attached? (A = factory molded, B = field attached)
- STYLE: what physical plug or receptacle configuration? (1–12)
TYPE I VS TYPE II
| Parameter | Type I | Type II |
|---|---|---|
| Conductors | 1 | 2 |
| Current rating | 25 A | 20 A |
| Voltage rating | 5,000 V | 600 V |
| Typical role | Higher-voltage, single-conductor AGL connection | Two-conductor, lower-voltage AGL connection |
| Common association | Primary circuit | Secondary / fixture-side connections |
Confirm the actual application against the approved project design. The type table is the formal classification; the "typical role" is a common association, not a rule. AC 150/5345-26E defines Type I and Type II by electrical rating only; it does not assign either Type to the primary or secondary circuit.
TYPE I TYPE II 1 conductor 2 conductors 25 A 20 A 5000 V 600 V
CLASS A VS CLASS B
| Class A | Class B |
|---|---|
| Factory molded to the cable | Field attached to the cable |
| Factory-controlled assembly | Installer-controlled assembly |
| Permanent cable/connector bond | Field assembly |
| Less field work | More field workmanship required |
| Common on manufactured cable assemblies | Useful for field termination |
Class A housings must bond to the cable sheath or conductor insulation during manufacture to give a watertight bond. Class B connectors must be supplied with installation instructions.
CLASS A: Factory -> Cable + Connector -> Finished assembly CLASS B: Cable + Connector kit -> Field assembly -> Completed connection
CONSTRUCTION: HOUSING, PIN AND SOCKET
A plug carries the contacts that mate with a corresponding receptacle. The electrical interface is a pin and a socket.
Housing
Elastomeric material that serves as insulation and sheath and fully encloses the pins or sockets. Gives mechanical protection, insulation, sealing and the cable interface.
Pin and socket material
At least 98% copper, or free-cutting brass alloy 360 (C36000), with required hardness and plating.
Plating
Tin or another suitable plating: reduces corrosion and helps keep contact resistance low.
Spring-loaded / slotted socket
Maintains contact pressure, which limits contact resistance, voltage drop, heating and intermittent connection.
ENVIRONMENT AND PERFORMANCE
| Requirement | Value / statement |
|---|---|
| Operating temperature | −55 °C to +65 °C (−67 °F to +149 °F), in weather, submerged or buried |
| Burial and chemicals | Direct earth burial; limited attack from oil, de-icing fluids and gasoline |
| Watertight seal | Between mated plug and receptacle, and between rubber and metal parts |
| Contact voltage drop at rated current | Type I max 7.5 mV · Type II max 6.0 mV |
| Static pull (mated pair) | Must withstand 10 lb (44 N) without separating |
| Class A bond strength | Pull load calculated from the conductor cross-section at 75% of an average tensile strength of 40,000 psi; cable/connector separation must not exceed 0.03 in (0.8 mm) |
That chain is why low contact resistance is central to connector quality. Electrical connection and waterproof connection are both required.
STYLES 1–12
| Style | Connector | Class | Type | Conductors | AC figure (App. A) |
|---|---|---|---|---|---|
| 1 | Plug | A | II | 2 | A-1 (detail A) |
| 2 | Plug | A | I | 1 | A-2 (detail A) |
| 3 | Plug | B | I | 1 | A-3 |
| 4 | Plug | B | II | 2 | A-4 |
| 5 | Plug | B | II | 1 | A-7 |
| 6 | Plug | A | II | 2 | A-8 |
| 7 | Receptacle | A | II | 2 | A-1 (detail B) |
| 8 | Receptacle | A | II | 2 | A-1 (detail C) |
| 9 | Receptacle | A | I | 1 | A-2 (detail B) |
| 10 | Receptacle | B | I | 1 | A-3 |
| 11 | Receptacle | B | II | 2 | A-5 |
| 12 | Receptacle | B | II | 1 | A-6 |
Styles 7 and 8 are not duplicate part numbers: they are different specified mechanical configurations. Style 6 has its own figure (A-8), separate from Style 1 (A-1).
READING A DESIGNATION
| Designation | Meaning |
|---|---|
| L-823, Type I, Class A, Style 2 | AGL connector spec · 1 conductor, 25 A, 5,000 V · factory molded · plug configuration |
| L-823, Type II, Class A, Style 7 | Two-conductor, 20 A, 600 V · factory molded · receptacle configuration |
Each plug and receptacle must be marked with the manufacturer identification and the L-823 designation including the style number.
PRIMARY AND SECONDARY APPLICATION
| Primary | Secondary |
|---|---|
| High-voltage series circuit | Individual fixture circuit |
| Type I commonly relevant | Type II commonly relevant |
| Single-conductor, 5,000 V class | Two-conductor, 600 V class |
| Cable-to-transformer primary interface | Transformer-to-fixture interface |
Class A primary connectors are molded to cable meeting the 2,001–5,000 V requirement (ICEA S-96-659 / NEMA WC 71), with cable voltage rating equal to or below the connector rating. Class A secondary connectors use cable meeting the 0–2 kV requirement (ICEA S-95-658 / NEMA WC 70). Always confirm the actual project configuration.
*Use the exact type and style required by the approved equipment. See Note 09 and Note 08.
COMPATIBILITY: NEVER SELECT BY APPEARANCE
Two connectors can look similar yet differ in type, class, style, contacts, voltage, current, cable size or mating geometry. Physical similarity does not prove electrical or mechanical compatibility. A connector and its cable form one assembly.
Compatibility check before ordering
- Type: I or II?
- Class: A or B?
- Style: correct plug or receptacle style?
- Cable: correct conductor and construction?
- Current and voltage rating
- Does the plug mate with the receptacle?
- Does it match the transformer or fixture?
CLASS B ASSEMBLY AND WORKMANSHIP
Class B pins and sockets must allow crimping to the conductor, and the contact must not be unacceptably damaged by crimping. For some configurations, silicone insulating compound fills internal spaces; assembly provisions guard against voids and compound intrusion.
Poor crimp
High resistance, loose contact, heating, mechanical failure, intermittent operation.
Voids
Moisture pathways, electrical stress concentration and reduced insulation performance.
Typical errors
Wrong strip length, wrong conductor size, wrong pin position, too little or contaminated compound, damaged housing, poor sealing.
Remember
Connector certification does not remove the need for correct installation workmanship.
CAPS AND SHORT-CIRCUITING CAPS
Caps protect connectors before mating from dirt, moisture, contamination and transport or storage damage. They are supplied with Class A connectors unless the buyer requests otherwise.
For certain Type II receptacles used in series applications, a short-circuiting plug-type cap may be required. It has internal jumpers on the proper pins, the same mating dimensions as the corresponding plug, and is permanently marked "S".
QUALIFICATION AND PRODUCTION TESTS
| Test | Requirement (AC 150/5345-26E) |
|---|---|
| Dielectric | Type I 15 kV DC · Type II 4.7 kV DC for 5 minutes, after water soak while immersed |
| Insulation resistance | Min. 25,000 MΩ after the test sequence; 10,000 MΩ in the later heated-water condition |
| Mechanical | Pull, separation and cable/connector bond tests |
| Electrical | Mated connector at rated current; contact voltage drop within limits |
| Weathering | 720 h xenon-arc and 100 h ozone; cracking can be grounds for rejection |
| Metal-bond (Class A) | In water, approx. 20 psi air from the cable end for 10 min; no bubbles |
| Chemical resistance | Housing exposed to specified chemicals at temperature for 20 days |
| Production | Visual and interface-dimension checks; dielectric 15 kV (Type I) / 4.7 kV (Type II) DC, which may be shortened to 1 second; minimum insulation resistance 75,000 MΩ (Type I) and 23,500 MΩ (Type II) |
Mate -> Water soak -> High-voltage test -> Insulation measurement -> Additional immersion / flexing -> Re-test
FIELD TESTING, HANDLING AND INSPECTION
Field tests may include continuity, insulation resistance and voltage-drop measurements, plus visual mating, connector condition, strain and sealing checks. Continuity is not insulation integrity: a connector can pass continuity and fail insulation.
Storage
Keep caps on; protect mating surfaces, oil, chemicals, heat and sunlight; no heavy objects on leads; avoid sharp bends; keep markings intact.
Never
Pull by the contacts, drag on the ground, strike with tools, force mismatched halves, mate contaminated contacts, cut molded cable, or modify a certified assembly without an approved process.
Inspect pin
Straight, clean, undamaged, correct geometry.
Inspect socket and housing
Socket not expanded, blocked or corroded, with good spring action; housing without cracks, cuts or deformation.
Cleanliness is part of electrical reliability: dirt or moisture on contacts causes resistance, tracking and intermittent operation. Do not force a connector that will not mate naturally; it may be the wrong style, damaged or contaminated.
FAILURE MODES AND FAULT-FINDING
| Failure mode | Cause / effect |
|---|---|
| High contact resistance | Heating and voltage drop; can become self-reinforcing |
| Open circuit | Broken conductor or poor contact |
| Insulation failure | Moisture, damage or ageing |
| Water ingress | Leakage and corrosion |
| Mechanical damage | Housing compromised |
| Incorrect assembly | Especially Class B |
An open primary connector breaks the series loop, so every light on that circuit goes out and the CCR may shut down on open-circuit protection; an open secondary connector usually affects one fixture.
One light off
- Check fixture
- Secondary connector
- Secondary cable
- Transformer
- Primary connector
Many lights off
- Check CCR
- Primary circuit and cable
- Primary connectors
- Transformers
Connector heating: inspect the connector and contacts, check the electrical connection, then current and cable. Likely causes are high contact resistance, poor crimp, wrong contact, contamination, corrosion, loose mating or damage. Low insulation: investigate cable, connector, transformer and moisture. A bad connector also affects LED fixtures (voltage drop, flicker, driver malfunction) and, indirectly, photometric output.
L-823 VS GENERIC CONNECTORS
A terminal block belongs inside protected equipment; an L-823 is designed for field AGL cable interfaces. A connector sold as "waterproof" is not automatically L-823 compliant: compliance covers ratings, dimensions, contact performance, environmental tests, cable compatibility, qualification and production requirements. Commercial terms such as inline connector, coupler or cable connector do not replace the formal Type + Class + Style; verify the manufacturer's exact FAA designation.
COMMON MISTAKES
Calling every connector "L-823"
Identify Type + Class + Style.
Selecting by cable size only
Cable size alone does not determine the connector.
Mixing plug styles
A plug must mate with the correct receptacle.
Ignoring Type I vs II
Fundamentally different electrical classifications.
Using an ordinary waterproof connector
Waterproof does not establish compliance.
Ignoring Class A vs B
Different installation considerations.
Reusing damaged connectors
Seals and contacts may no longer protect.
Leaving connectors uncapped, forcing mating, poor crimping
Contamination, damaged pins and heating.
Procurement: do not write only "L-823 connector – Qty 100"
L-823 + Type + Class + Style + cable size + cable type + mating half + current + voltage + application + standard / approval L-823 Connector Type: I | Class: A/B | Style: XX Cable: ____ | Conductor: ____ | Mating connector: ____ Quantity: ____ | Compliance: FAA / project specification
On receipt
Check datasheet, compliance and certification documents, test documentation, L-823 marking, manufacturer, style number, type and part number. Then check for cracks, cuts, deformation, damaged cable sheath, pins or sockets, corrosion, contamination, correct cap and dimensions. Before assembling Class B: right kit, cable, cable size, conductor preparation, crimp tooling, contact, housing, compound and instructions; afterwards check pin position, crimp, compound fill, housing closure, continuity and insulation as required.
QUICK REVISION
Remember
- TYPE = electrical (I: 1 conductor, 25 A, 5,000 V · II: 2 conductors, 20 A, 600 V)
- CLASS = attachment (A factory molded · B field attached)
- STYLE = geometry (plugs 1–6 · receptacles 7–12)
- Qualification test voltages are not field test voltages
- Many lights off: go upstream · one light off: go local
- Procurement = Type + Class + Style + Cable + Current + Voltage + Mating half + Application + Standard
L-823
┌────────────┼────────────┐
TYPE CLASS STYLE
I / II A / B 1–12
Electrical Assembly Geometry
└────────────┼────────────┘
CABLE CONNECTOR
↓
PRIMARY / SECONDARY AGLEXAM / INTERVIEW QUESTIONS
What is an L-823 connector?
An airport-lighting plug/receptacle cable connector for underground power cables, isolation-transformer leads and light-fixture leads.
What is Type I?
1 conductor, 25 A, 5,000 V.
What is Type II?
2 conductors, 20 A, 600 V.
What is Class A?
Factory molded to the cable.
What is Class B?
Field attached to the cable.
What do style numbers identify?
The specified physical plug or receptacle interface configuration.
How many plug and receptacle styles are there?
Six plug styles (1–6) and six receptacle styles (7–12).
Why must an L-823 connector be watertight?
To protect the connection from the moisture, groundwater and flooding met in airfield installations.
Why is contact resistance important?
High resistance causes voltage drop and I²R heating.
What is the difference between Type and Class?
Type is the electrical classification; Class is the attachment method.
Can any Type I plug mate with any Type I receptacle?
No. The correct mating style/configuration must be used.
Can a connector be selected only by current?
No. Type, class, style, cable, voltage, mating half and application must all be verified.
Why do connector faults matter in the primary circuit?
An open or faulty primary connector breaks the series loop, so the whole circuit is affected, not one fitting, and the CCR may shut down on open-circuit protection.
Why does a bad secondary connector usually fail only one light?
The secondary normally supplies one individual fixture.
Why are Class B connectors more sensitive to workmanship?
They are assembled onto the cable in the field.
Why is continuity not enough?
It does not prove insulation integrity, sealing, contact resistance or mechanical condition.
What is the short-circuiting cap marking?
"S", with the same mating dimensions as the corresponding plug.
Can I use qualification test voltages in the field?
No. Use the approved maintenance or commissioning procedure.
FINAL STUDY TAKEAWAY
The L-823 connector is a critical electrical and environmental interface in an AGL system. Remember three words: Type (electrical: I = 1 conductor, 25 A, 5,000 V; II = 2 conductors, 20 A, 600 V), Class (attachment: A = factory molded, B = field attached) and Style (physical configuration: plugs 1–6, receptacles 7–12).
L-823 knowledge = Type + Class + Style + Cable + Contact + Insulation + Sealing + Installation + Testing + Compatibility.
ENGINEERING & EXPERT NOTES
Workmanship Decides Whether the Connector Lasts
AssemblyClass B connectors depend on clean preparation, correct tools and complete sealing. Training and recorded procedure matter as much as the part.
Compatibility Must Be Verified, Not Assumed
SelectionA connector that mates physically may not be the right type, class or style for the circuit. Check the full designation and the cable it was designed for.
Look for the Water Path, Not Just the Corroded Contact
Failure ModeCorrosion at a pin is the result. The seal, the pit drainage and the cable entry are usually the cause.
Heat and Intermittency Point to Contact Resistance
DiagnosisA warm connector or a fault that comes and goes with load or weather suggests a marginal contact. Re-make it with new parts and seals.
REFERENCES & FURTHER READING
These notes are a study aid. Verify details against the primary sources below.
| # | Source | Use it for |
|---|---|---|
| 1 | FAA AC 150/5345-26E – L-823 Plug and Receptacle, Cable Connectors (16 Dec 2021) | Classification, construction, performance, qualification and production tests, Appendix A styles. |
| 2 | AC 150/5345-26E (PDF) | Full text and figures. |
| 3 | ICEA S-96-659 / NEMA WC 71 and ICEA S-95-658 / NEMA WC 70 | Cable standards referenced for Class A primary (2,001–5,000 V) and secondary (0–2 kV) molded connectors. |
Read the Notes. Close the Gaps. Build AGL Expertise.
Study notes give you the concepts and the exam logic — Precision AGL Academy is where they connect into real technical capability.
Learn how AGL fundamentals, systems, testing, photometry, maintenance and troubleshooting connect through structured technical training, well beyond what a set of notes can cover.
Study smarter. Train deeper. Build technical capability.
Build structured knowledge in: