iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Type 1 and Type 2 surge protective devices (SPDs) are different primarily because of where they are intended to be installed. Under UL 1449, a listed Type 1 SPD may be used on the line side or load side of service-equipment overcurrent protection when its listing permits it. A Type 2 SPD is intended for the load side. Neither label, by itself, means that one device is universally “stronger” or safer.
Choosing correctly requires matching the device listing and wiring instructions to the service voltage, system configuration, available fault current, enclosure, installation location and locally adopted electrical code. Work at a service entrance or distribution panel can be lethal; a qualified electrician should determine suitability and perform the installation.
Type 1 and Type 2 SPD: the short answer
The UL 1449 type is an installation-location category tied to service-equipment overcurrent protection:
| Question | Type 1 SPD | Type 2 SPD |
|---|---|---|
| Where is it intended to be installed? | On the line side or load side of the service-equipment overcurrent protective device, where the particular listing allows it | On the load side of the service-equipment overcurrent protective device |
| What does the type tell you? | Its permitted relationship to service overcurrent protection under UL 1449 | Its permitted load-side installation category under UL 1449 |
| Does the type alone indicate better protection? | No. Compare the actual ratings, compatibility, listing, enclosure and installation requirements. | |
The exact model label, wiring diagram and installation manual control. A product marketed as Type 1 or Type 2 must still be suitable for the electrical system in which it will be installed.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
What “line side” and “load side” mean
Line side
The line side is the portion of the service conductors before the service equipment’s overcurrent protective device, such as the main disconnect or main breaker. It can remain energized even when downstream breakers are off. A line-side connection therefore has unusually serious shock and arc-flash implications and is not a homeowner wiring project.
Load side
The load side is downstream of the service-equipment overcurrent protective device. Main and branch panels, feeder equipment and many panel-mounted SPDs are load-side applications. Turning off a main device may not make every conductor safe, so the electrician must verify the isolation procedure and the equipment’s construction.
Manufacturer explanations use these terms differently in simplified diagrams. Treat them as a description of the connection point relative to the service overcurrent device, not as permission to improvise a connection.
Do these 3 things before closing this tab:
1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitchesWhat UL 1449 says about the two types
UL 1449 is the US safety standard discussed by the technical sources for permanently connected SPDs. An Intertek overview reproduces scope language describing Type 1 devices as permanently connected products intended between the service-transformer secondary and the line side of service-equipment overcurrent protection, while also covering specified load-side applications and enclosures. ABB’s UL 1449 5th Edition selection guide summarizes Type 1 as line-side or load-side and Type 2 as load-side only.
Schneider Electric’s US FAQ similarly describes Type 1 as installable between the utility service-transformer secondary and the line side of the main service equipment’s overcurrent protective device. Its module explanation places Type 2 devices on the load side, including branch-panel applications. These descriptions explain the category; they do not replace the listing or the local code adopted for a particular installation.
Why the listing matters more than the label on a sales page
A catalog may use “Type 1” or “Type 2” as a headline, but the device itself should carry the applicable certification marking and installation information. Check the nameplate and manual for:
- UL 1449 status and the exact type designation
- Nominal system voltage and frequency
- System configuration, such as single-phase or three-phase and the available conductor connections
- Maximum continuous operating voltage and the terminals or leads provided
- Voltage protection rating (VPR), where the UL terminology applies
- Short-circuit current rating and any fault-current limitation stated by the manufacturer
- Required conductor size, torque and lead-length limits
- Enclosure rating and suitability for the installation environment
- Any required or permitted external overcurrent device
Type 1 is not automatically “stronger” than Type 2
Type designation describes intended location, not a universal performance ranking. A properly selected Type 2 device can be the correct protection for a downstream panel, while a Type 1 device can be unsuitable if its voltage, configuration, enclosure or connection method does not match the service.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Compare devices using the parameters that apply to your installation. A lower VPR may be desirable for a compatible system, but the number must be evaluated with the device’s operating-voltage rating and wiring arrangement. Surge-current capability and fault-current withstand are different concepts: a high surge-current figure does not by itself prove that the device can safely interrupt or survive a prospective utility fault. NEMA guidance cautions against treating surge current and fault current as interchangeable selection criteria.
Also consider physical placement. A device with excellent published ratings can perform poorly if the connecting conductors are unnecessarily long, routed incorrectly or terminated outside the manufacturer’s instructions. The electrician should follow the supplied diagram and torque values rather than copying a connection from another panel.
External overcurrent protection and disconnects
There is no single rule that applies to every Type 1 or Type 2 SPD. The product listing, wiring instructions and applicable code determine what is required.
ABB’s guide describes its Type 1 category as listed without requiring external overcurrent protection. For its Type 2 examples, ABB recommends a dedicated breaker as a local disconnect. Intermatic states that its Type 2 panel-connected units require a dedicated breaker. Those statements are product-specific and should not be generalized to every manufacturer or model.
Quick wins for a faster PC:
Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →How to interpret a breaker requirement
- Required overcurrent protection: The manual may specify a breaker or fuse rating that protects the SPD conductors.
- Local disconnect: A dedicated breaker can provide a means of disconnecting the SPD for servicing, even where the SPD’s listing does not require it as its primary protection.
- Panel compatibility: A breaker must be approved for the panelboard and installed in a permitted position; a spare space is not automatically an acceptable connection point.
- Coordination: The electrician must verify that the breaker or fuse rating, interrupting capacity and conductor size are compatible with the panel and available fault current.
Do not remove a specified protective device because another SPD did not require one, and do not add a breaker solely because a generic article said all Type 2 units need one.
UL 1449 versus IEC 61643: do not translate the labels directly
US-oriented material commonly uses UL 1449 Type 1 and Type 2. IEC 61643 uses a different classification vocabulary, commonly Class I and Class II. Bourns describes Class I testing with impulse current, Iimp, using a 10/350 μs waveform, and Class II testing with maximum discharge current, Imax, using an 8/20 μs waveform.
| Framework | Common category terms | Test parameter highlighted in the technical comparison | What it does not prove |
|---|---|---|---|
| UL 1449 | Type 1 and Type 2 | Installation category relative to service-equipment overcurrent protection, plus the product’s listed ratings | It does not convert automatically to an IEC class or establish a universal performance hierarchy. |
| IEC 61643 | Class I and Class II | Class I: Iimp with a 10/350 μs waveform; Class II: Imax with an 8/20 μs waveform | An IEC class does not prove that a device has a particular UL 1449 type listing. |
A product carrying an IEC marking may be appropriate in a jurisdiction using IEC requirements, but it is not automatically a UL-listed Type 1 or Type 2 device. Verify the certification recognized by the authority having jurisdiction and the device’s installation instructions.
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
How to choose an SPD for a real installation
Step 1: Identify the connection point
Determine whether the proposed SPD will connect before or after the service-equipment overcurrent protective device. If the point is line side, only a device whose listing and instructions permit that application should be considered. If it is a panel or feeder connection downstream, the device must be suitable for load-side use.
Step 2: Identify the electrical system
Record the service voltage, phase arrangement, frequency, grounding or bonding arrangement and conductor configuration. An SPD designed for one voltage or system topology cannot be assumed safe on another. Use the panel schedule and equipment nameplates, then have the electrician verify the information at the equipment.
Step 3: Check the listing and ratings
Read the actual product label and installation manual. Confirm the UL 1449 type, VPR or other applicable protection information, maximum continuous operating voltage, short-circuit current rating, enclosure requirements and permitted connection modes. Do not select solely from a retailer’s filter for “whole-house surge protection.”
Step 4: Resolve overcurrent and disconnect requirements
Look for explicit language such as “external overcurrent protection required,” a fuse or breaker size, or a recommendation for a dedicated disconnect. If the instructions are silent or ambiguous, the electrician should obtain clarification from the manufacturer instead of inferring a rule from another model.
Step 5: Verify physical and environmental fit
- Is there adequate space and an approved mounting method?
- Does the enclosure suit indoor, outdoor, wet or dusty conditions?
- Can the conductors be routed within the manufacturer’s stated length and bend requirements?
- Are the terminals, wire sizes and torque values compatible with the panel?
- Will the device’s status indicator remain visible for inspection?
Step 6: Check local code and obtain the required inspection
NEC edition and adoption vary by state, municipality and other jurisdiction. The sources reviewed here do not establish which edition applies at your address or make a site-specific wiring determination. The authority having jurisdiction and the licensed electrician must resolve local requirements, permits and inspection.
The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Installation workflow for a qualified electrician
The following is a planning sequence, not a do-it-yourself wiring procedure. Service and panel work can expose a worker to energized conductors even when a breaker appears off.
- Review documentation: Compare the SPD label, listing, wiring diagram and panel manufacturer requirements before opening equipment.
- Plan isolation: Identify the service disconnect, upstream sources, generator or inverter sources and the test equipment needed to verify absence of voltage.
- Confirm the connection location: Ensure the selected Type 1 or Type 2 category matches the actual line-side or load-side point.
- Install the specified protective device: Fit the required breaker or fuse, if any, using an approved device and the manufacturer’s stated rating.
- Mount and wire the SPD: Follow conductor, bonding, polarity, phase and torque instructions exactly; keep leads as short and direct as the manual requires.
- Check mechanical work: Inspect terminal torque, conductor routing, enclosure closure, labeling and unused openings.
- Test and document: Re-energize under the site’s safety procedure, check the status indication and record the model, location, date and protective-device details.
A status light generally indicates that the SPD is connected and its monitoring circuit sees an expected condition; it is not a guarantee that every surge has been stopped or that the protected equipment is indestructible.
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
Common selection mistakes and how to correct them
“Type 1 is always better”
Why it fails: The type identifies installation category, not a universal strength score.
Correction: Start with the connection location, then compare compatibility, listing, VPR, short-circuit rating, enclosure and installation requirements.
Crashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteWindows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallInstalling a Type 2 device on the line side
Why it fails: Type 2 is intended for load-side installation under UL 1449.
Correction: Use a device whose listing expressly permits the proposed line-side application, or move the protection to an approved load-side point.
Assuming every Type 2 needs the same breaker
Why it fails: External overcurrent and disconnect requirements vary by product.
Correction: Follow the exact manual and listing for that model and coordinate the device with the panel.
Recommended Free Tools
Using an IEC class as a UL type substitute
Why it fails: IEC Class I/II and UL 1449 Type 1/2 come from different standards frameworks and test methods.
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Correction: Select the certification recognized in the installation’s jurisdiction and verify any additional approvals.
Ignoring fault current
Why it fails: Surge-current and fault-current ratings answer different safety questions.
Correction: Have the installer verify the SPD short-circuit current rating and the protective device’s interrupting capacity against the installation’s available fault current.
Copying a diagram from another panel
Why it fails: Panel construction, grounding, breaker compatibility and service arrangement differ.
Correction: Use the exact SPD and panel instructions, with the local code official’s requirements where applicable.
What protection an SPD can and cannot provide
An SPD provides a controlled path for transient overvoltage energy, limiting the voltage presented to connected conductors within the limits of its design. It does not make a building immune to lightning, eliminate every source of electrical disturbance or guarantee that connected electronics will survive every event.
Protection is a system decision. The service entrance, distribution panels, branch circuits, grounding and bonding, communications pathways and sensitive equipment all affect the result. The type label addresses one part of that system: the permitted installation relationship to service overcurrent protection.
Safety requirements and professional responsibility
NEMA’s Surge Protection Institute states: “All ac power SPDs should be Listed or Recognized to ANSI/UL 1449 and installed in accordance with the manufacturer’s installation instructions.” That guidance is especially important for line-side work and panel modifications.
- Do not remove panel covers or approach service conductors unless you are qualified, authorized and equipped for the hazard.
- Do not assume that switching off a main breaker de-energizes line-side conductors.
- Do not bypass a specified fuse, breaker, disconnect or bonding connection.
- Do not mix a device’s wiring diagram with instructions from another model.
- Use the authority having jurisdiction’s adopted code and inspection process.
Decision checklist: Type 1 or Type 2?
| If your situation is… | Start with… | Then verify… |
|---|---|---|
| The SPD is proposed before the service overcurrent device | A UL 1449 Type 1 device whose listing permits that line-side application | Service voltage and configuration, enclosure, conductor method, fault-current rating, instructions and local code |
| The SPD will connect in a main or branch panel downstream of service overcurrent protection | A UL 1449 Type 2 device listed for that load-side installation | Panel and breaker compatibility, any required dedicated breaker, ratings, lead routing and enclosure |
| The product is marked only with IEC terminology | The IEC class recognized for your jurisdiction | Do not assume it carries a UL 1449 Type 1 or Type 2 listing |
| The listing or manual conflicts with a generic buying guide | The product listing and manufacturer instructions | Ask the manufacturer or qualified electrician before installation |
Bottom line for homeowners, facilities teams and designers
Use the installation point to make the first distinction: Type 1 can cover qualifying line-side or load-side applications, while Type 2 is for load-side installation. Then stop treating the type as a quality ranking. Confirm the exact listing, service compatibility, ratings, enclosure, overcurrent or disconnect requirements and local code. A qualified electrician should make the site-specific decision and install the SPD according to its documentation.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
