Choosing the right lamp cord is an important part of restoring a vintage lamp, replacing an old power cord, or creating a custom pendant light. But with options like SPT-1, SPT-2, SVT, 18/2, 20/2, and 22/2 wire, understanding the differences can be confusing.
Should you use flat or round lamp wire? Is 18/2 thicker than 20/2? What's the difference between SVT/2 and SVT/3? And which cord is best for a pendant, table, or floor lamp?
At NostalgicBulbs.com, we carry a variety of lamp wires, including flat parallel cords, round pendant cords, and decorative lamp wire.
This guide explains the differences, what the numbers and letters mean, and how to select the right cord for your lighting project.
What Does SPT Mean in Lamp Cord?
SPT stands for Service Parallel Thermoplastic.
SPT is a type of flexible electrical cord with two insulated conductors running side by side, creating a flat profile.
SPT cords are commonly found on portable table lamps, floor lamps, and other compatible electrical products.
The two most familiar types are SPT-1 and SPT-2.
SPT-1 Lamp Cord
SPT-1 is a flat parallel cord with a typical nominal insulation thickness of 0.030 inches (0.762 mm).
Its relatively slim profile makes it a common option for compatible table lamps and floor lamps.
One example is our Clear Silver 18/2 SPT-1 Lamp Wire, which features two 18 AWG conductors and is UL listed.
SPT-2 Lamp Cord
SPT-2 has a similar flat, parallel construction but uses thicker insulation.
Its typical nominal insulation thickness is 0.045 inches (1.143 mm).
When comparing SPT-1 and SPT-2 cords of the same conductor gauge, SPT-2 generally has a larger outside profile.
The thicker insulation does not automatically mean the cord can carry more electrical current. Current capacity also depends on conductor size, the cord's ratings, and installation requirements.
SPT-1 vs. SPT-2 Comparison
| Feature | SPT-1 | SPT-2 |
|---|---|---|
| Shape | Flat | Flat |
| Typical insulation thickness | 0.030" | 0.045" |
| Relative outside size at same gauge | Smaller | Larger |
| Common standardized conductor gauges | 20 and 18 AWG | 18 and 16 AWG |
| Typical use | Compatible portable lamp cords | Compatible portable lamp cords |
Important: Always match the cord to the fixture's electrical requirements and the specifications of any plugs, switches, dimmers, or strain relief components.
Understanding 18/2, 20/2, and 22/2 Lamp Wire
Lamp wire is often identified using two numbers separated by a slash.
For example, 18/2 means 18 AWG wire with two conductors.
The first number identifies the wire gauge, while the second indicates the number of conductors.
AWG stands for American Wire Gauge.
One important rule is that the smaller the AWG number, the larger the conductor.
Wire Gauge Diameter Comparison
| Wire gauge | Nominal conductor diameter | Conductors in /2 cord |
|---|---|---|
| 18 AWG | 1.024 mm (0.0403") | 2 |
| 20 AWG | 0.812 mm (0.0320") | 2 |
| 22 AWG | 0.644 mm (0.0253") | 2 |
These measurements are nominal solid-wire equivalents. Actual stranded conductor bundle dimensions and finished cord dimensions may differ.
18/2 Lamp Wire
18/2 contains two 18 AWG conductors.
It is commonly found in approved lamp cords and cord sets, including many table and floor lamp applications.
Our Clear Silver 18/2 SPT-1 Lamp Wire is a UL-listed example.
20/2 Lamp Wire
20/2 contains two 20 AWG conductors, which are smaller than 18 AWG conductors.
Our Clear Gold 20/2 Parallel French Wire offers a decorative clear-gold appearance.
This particular wire is not UL listed. Its use must be evaluated against its actual manufacturer specifications and the requirements of the intended application.
22/2 Lamp Wire
22/2 contains two 22 AWG conductors, making it the smallest conductor size among the three compared here.
Our Clear Gold 22/2 Parallel French Wire is another decorative parallel wire option.
This product is not UL listed and should not be represented as standard UL-listed SPT-1 or SPT-2 cord.
The 22/2 designation alone does not establish suitability for a 120V lamp or pendant fixture. Check the product's electrical classification, ratings, and intended use before selecting it.
Is Thicker Wire Always Better?
Not necessarily.
Larger conductors generally have lower electrical resistance than smaller conductors of the same material and length. However, wire gauge is only one factor in choosing lamp cord.
You must also consider the cord's electrical rating, insulation, temperature rating, grounding requirements, fixture design, and compatibility with the other electrical components.
What Does SVT Mean in Lamp Cord?
SVT stands for Service Vacuum Thermoplastic.
SVT is a flexible electrical cord that typically has a round profile, with individually insulated conductors enclosed in an overall protective jacket.
Unlike flat SPT cord, SVT has a smooth, round exterior.
This makes it a popular appearance choice for compatible pendant lights and other lighting applications where the cord remains visible.
SVT/2 vs. SVT/3: What's the Difference?
The primary difference is the number of conductors.
SVT/2 — Two-Conductor Round Cord
Our Black Round SVT/2 Lamp Cord contains two 18 AWG conductors.
Product specifications include:
-
18/2 conductor configuration
-
Round black jacket
-
Outside diameter: 0.234"
-
Maximum rated voltage: 300V
-
UL listed
This cord is an option for compatible two-conductor lighting assemblies that do not require an equipment grounding conductor.
SVT/3 — Three-Conductor Round Cord with Ground
Our Black Round SVT/3 Lamp Cord contains three 18 AWG conductors, including a green equipment grounding conductor.
Product specifications include:
-
18/3 conductor configuration
-
Round black jacket
-
Green equipment grounding conductor
-
Outside diameter: 0.250"
-
Maximum rated voltage: 300V
-
UL listed
SVT/3 may be appropriate for compatible fixtures requiring a grounding connection.
The green conductor must be properly connected to the fixture's designated grounding point. A three-conductor cord does not automatically make a fixture properly grounded.
SVT/2 vs. SVT/3 Comparison
| Feature | SVT/2 | SVT/3 |
|---|---|---|
| Wire gauge | 18 AWG | 18 AWG |
| Conductors | 2 | 3 |
| Green ground conductor | No | Yes |
| Shape | Round | Round |
| Outside diameter | 0.234" | 0.250" |
| Rated voltage | 300V | 300V |
| UL listed | Yes | Yes |
SPT vs. SVT: Which Lamp Cord Is Better?
Both SPT and SVT are flexible cord constructions, but they differ in appearance and physical design.
SPT cord has a flat, parallel profile that is commonly used in compatible portable table lamps and floor lamps.
SVT cord has a round, jacketed profile that can provide a clean appearance in certain pendant lighting applications.
Neither cord is automatically better or safer for every fixture.
The correct choice depends on the lamp's design, conductor requirements, grounding, cord ratings, and compatibility with the fixture's hardware.
Which Lamp Cord Is Best for Pendant Lights?
Pendant lights often feature visible wiring, making appearance an important consideration.
Round black SVT cord is a popular visual choice for vintage-inspired and industrial-style pendants.
For compatible two-wire pendant assemblies, SVT/2 may be an option.
For compatible assemblies requiring an equipment grounding conductor, SVT/3 provides a green grounding conductor.
However, not every flexible cord is approved to support the weight of a hanging light fixture. A pendant may require a separate mechanical support system or an approved cord-suspended fixture assembly.
Always follow the pendant manufacturer's installation instructions and use compatible cord grips, strain relief, and support hardware.
Which Lamp Cord Is Best for Table Lamps?
Flat parallel lamp cord is commonly used with portable table lamps.
For compatible table lamp applications, UL-listed 18/2 SPT-1 cord can be a practical option.
Its flat construction can provide a low-profile appearance behind furniture and along surfaces.
When replacing an existing cord, check the lamp's original wiring configuration, grounding requirements, socket, switch, plug, and strain relief.
If your lamp uses an inline switch or dimmer, verify that the component is designed for the exact cord type and size.
Which Lamp Cord Is Best for Floor Lamps?
Floor lamps also commonly use flexible power cords.
A compatible UL-listed SPT cord may be appropriate for many portable floor lamp designs.
However, floor lamps can vary significantly. Some include multiple sockets, built-in switches, dimmers, or grounded metal components.
Choose the cord based on the lamp's electrical design rather than assuming all floor lamps use the same wire.
A floor lamp that requires equipment grounding needs a suitable grounding conductor and correctly connected grounding hardware.
What About Cloth-Covered and Twisted Lamp Wire?
Decorative cloth-covered and twisted lamp wires are popular for vintage lighting projects.
They can complement brass sockets, exposed Edison bulbs, and industrial-style fixtures.
However, the decorative textile covering does not identify the electrical cord type underneath.
Cloth-covered wire may have different internal constructions, conductor sizes, insulation materials, and electrical ratings.
Before using decorative lamp wire, verify the manufacturer's specifications and whether the wire is approved for the intended fixture and installation.
Frequently Asked Questions
What is the difference between SPT-1 and SPT-2?
Both are flat parallel cord types. SPT-2 typically has thicker insulation than SPT-1, but the correct choice depends on the electrical requirements of the lamp and its components.
Is 18/2 wire thicker than 20/2?
Yes. The individual 18 AWG conductor is larger than a 20 AWG conductor. The overall finished cord dimensions depend on insulation and construction.
Can I use 22/2 wire for a table lamp?
Do not assume that 22/2 wire is suitable for a mains-powered table lamp. Verify its specific electrical ratings, certification status, and approved use.
What is the difference between SVT/2 and SVT/3?
SVT/2 has two conductors. SVT/3 has three conductors. The SVT/3 cord sold by NostalgicBulbs.com includes a green equipment grounding conductor.
Is SVT better for pendant lights?
Round SVT cord can provide an attractive appearance for pendant lighting, but it must be suitable for the particular fixture. Cord-supported pendants require appropriate support and strain relief.
Can I use an SPT-2 dimmer on SPT-1 cord?
Only if the dimmer manufacturer specifically approves the cord. Some dimmers are designed exclusively for SPT-2 and may not make reliable connections with other cord constructions.
Does UL listing matter when choosing lamp wire?
UL listing provides evidence that a product has been evaluated to an applicable safety standard. Always check the exact product's certification and intended use. A listed cord alone does not make the completed lamp or fixture listed.
Shop Lamp Cord and Wire at NostalgicBulbs.com
Whether you're restoring a vintage table lamp, replacing a floor lamp cord, or creating a custom pendant, choosing the correct wire is an important part of the project.
At NostalgicBulbs.com, you'll find a selection of flat parallel lamp cords, round pendant wires, decorative lamp wire, and lamp-making accessories.
Explore our collections:
Find the right cord for your next lighting project at NostalgicBulbs.com.
Safety note: Disconnect power before servicing a lamp. Electrical cord selection and installation must follow applicable codes, product ratings, and manufacturer instructions. Consult a qualified electrician when necessary.