LC Patch Cord Buying Guide: Fiber, Polish, Polarity, Length and Jacket
To buy the right LC patch cord, fix nine things: connector at each end (LC-LC or LC-SC), fiber type (OS2, OM3, OM4 or OM5, matching the link), polish (UPC or APC, never mixed), simplex or duplex, polarity (A-to-B for a normal transmit-to-receive link), length, jacket rating (OFNR, OFNP or LSZH for the building), and the loss and inspection you require. Most failed LC orders come from three errors: wrong fiber type, APC/UPC mismatch and wrong polarity.
Scope of this guide: buying duplex and simplex LC (and LC-SC) patch cords. For the connector comparison itself see LC vs SC; for MPO cords see the MTP/MPO patch cable ordering checklist. Standards checked: ANSI/TIA-568.3-D, TIA-598, IEC 61754-20, NEC Article 770, 29 October 2026.
1. Connector at Each End
LC (1.25 mm ferrule, IEC 61754-20) is the connector on SFP, SFP28, QSFP duplex optics and most high-density panels. Use LC-SC only where an older panel or device has SC ports. Check each end separately: LC-LC, LC-SC and SC-SC are different products.
2. Fiber Type
Match the cord to the cabling and optics, never the other way round. See single-mode vs multimode fiber.
| Fiber | Core | Jacket colour (TIA-598) | Use |
|---|---|---|---|
| OS2 single-mode | 9 µm | Yellow | LR/FR/DR optics, any long link |
| OM3 | 50 µm | Aqua | Existing OM3 plant |
| OM4 | 50 µm | Aqua (violet in some regions) | New multimode SR links |
| OM5 | 50 µm | Lime green | SWDM/BiDi multimode |
Bend-insensitive fiber (G.657.A1/A2 single-mode, bend-insensitive OM4) helps in dense patch fields; see bend-insensitive fiber.
3. Polish: UPC or APC
| UPC | APC | |
|---|---|---|
| End face | Domed, flat contact | 8° angled |
| Connector colour | Blue (SM), beige/aqua (MM) | Green (SM only) |
| Typical RL, single-mode | ≥50 dB | ≥60 dB |
| Used for | Most Ethernet duplex optics | PON, RF/video, some high-speed SM links |
UPC and APC must never be mated: the angled and flat faces leave an air gap and can damage the end faces. See APC vs UPC.
4. Simplex or Duplex
Duplex (two fibers, clipped LC pair) is the default for transceivers, which transmit on one fiber and receive on the other. Simplex is for BiDi optics, test leads and some splitters.
5. Polarity: A-to-B or A-to-A
TIA-568.3-D duplex patch cords are A-to-B: position A at one end connects to position B at the other, so transmit reaches receive. A-to-A cords (straight through) are used only where the cabling between already crosses the pair. If a link shows no light, an A-to-A/A-to-B mix-up is a common cause; reverse the pair at one end where the duplex clip allows it.
6. Length
Measure the actual route through cable managers, add slack for one re-termination-free move, and choose the next standard length. Excess slack crowds cable managers and is a common source of bend loss. Huawellux lists 1, 2, 3, 5, 7, 10 and 15 m; other lengths are built to order.
7. Jacket Rating
| Rating | Where | Standard |
|---|---|---|
| OFNR (riser) | General building and vertical risers, US | NEC Article 770, UL 1666 |
| OFNP (plenum) | Air-handling spaces, US; can replace OFNR | NEC Article 770, NFPA 262 |
| LSZH | Europe, Asia, enclosed spaces | IEC 60332, IEC 61034, IEC 60754 |
In the EU, check the CPR class (EN 50575) your project requires. See OFNP vs OFNR vs LSZH.
8. Loss and Inspection
TIA-568.3-D allows up to 0.75 dB per mated pair. Low-loss cords leave more of the optics' budget for the rest of the link. Ask for the IL and RL results per cord and an end-face inspection to IEC 61300-3-35. See insertion loss vs return loss.
9. Labels and Packing
For projects, ask for labels at both ends using your own port or circuit numbering, and individual bagging per cord so cords arrive sorted by rack.
Order Checklist
| Line | Example |
|---|---|
| Connectors | LC-LC |
| Fiber | OS2 G.657.A1 |
| Polish | UPC both ends |
| Count | Duplex |
| Polarity | A-to-B |
| Length | 3 m |
| Jacket | OFNR, yellow |
| Loss / test | IL ≤0.35 dB, RL ≥50 dB, test report |
| Labels / qty | Both ends, customer numbering; 200 pcs |
For non-standard cords, use the custom fiber patch cord spec template.
Frequently Asked Questions
What is the difference between A-to-B and A-to-A LC patch cords?
An A-to-B duplex cord crosses transmit to receive and is the TIA-568.3-D standard for equipment links. An A-to-A cord is straight through and is used only where the cabling already crosses the pair.
Can I use an OM4 LC patch cord on an OM3 link?
OM3 and OM4 have the same 50 µm core and mate with low loss; the link performs to the lower grade. Do not mix 50 µm with 62.5 µm or single-mode.
Should LC patch cords be UPC or APC?
Most Ethernet duplex optics use UPC. Use APC only where the equipment or panel is APC (green); never mate APC with UPC.
What jacket do I need for an LC patch cord?
OFNR for general US building use, OFNP in plenum air spaces, and LSZH where low smoke and zero halogen are required, such as many European and Asian projects.
How long should a patch cord be?
Measure the route through the cable managers and choose the next standard length up; avoid large slack loops in dense racks.
Huawellux LC and SC Patch Cords
Huawellux lists LC-LC, LC-SC and SC-SC cords, simplex or duplex, in OS2, OM4 and OM5, 1–15 m, with UPC or APC selectable per end, A-to-A or A-to-B polarity and an OFNR jacket; OFNP, OM3, other lengths and other options are built to order. Listed OS2 cords use G.657.A1 fiber with a 10 mm minimum fiber bend radius; listed OM4 cords use bend-insensitive fiber.
Huawellux's specification for MPO and MTP® assemblies is insertion loss ≤0.35 dB for single-mode and multimode, with return loss >60 dB single-mode (OS2, APC) and >30 dB multimode (OM3/OM4/OM5). LC and SC patch cords are listed at insertion loss ≤0.35 dB and return loss ≥60 dB (single-mode APC), ≥50 dB (single-mode UPC) and >30 dB (multimode) on each product page. Every Huawellux product receives end-face visual inspection under a 400x video microscope and is tested for insertion loss (IL) and return loss (RL) before it ships. Interferometric end-face geometry (fiber height, coplanarity, end-face angle and radius) is checked by sample-based testing in standard production, and 100% interferometer testing of a batch is available on request. Dust caps are fitted on every connector, and a formal test report is available on request.
Huawellux replies to inquiries within 24 hours. Listed standard products are prepared in 1–7 business days. Custom orders typically take 1–5 business days to complete production, with final timing confirmed case by case in the quotation. For special/custom requirements, MOQ is 2 km of fiber length. Standard listed patch cords have no formal MOQ. Labels printed to your own numbering scheme are free. The sample fee is credited against the bulk order. Standard products carry a one-year limited warranty under the published returns and warranty policy.
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