How to Specify Surge Protection for an ITS Project

By Dan Rebeck, Product Line Manager, Product Management, Infinite Electronics 

Traffic signals, cameras, and message signs carry much of the load in keeping roads safe. They sit outdoors, connected to long cable runs that pick up lightning energy like an antenna. When a surge destroys that equipment, drivers reach intersections with no signal telling them who goes first, operators lose the cameras that show a crash or a stalled vehicle, and message signs stop warning drivers about hazards ahead. Every hour until the repair is an hour of added risk. 

Surge protection is often a late line item, and a vague specification invites mismatched products. This guide covers the standards to name, where to place protection, how to handle PoE++, which compliance checks to run early, and the mistakes to avoid when setting up your Intelligent Transportation System (ITS) projects. 

Key Takeaways 

•        Name the listing for each circuit: UL 1449 for AC power, UL 497B for data lines. UL listed alone is not enough. 
•        Protect every entry point: AC power, data, and PoE lines, at the cabinet and near the equipment. 
•        Ground first. A protector needs a solid path to ground to work. 
•        State the PoE type, the data speed, and the current rating. PoE++ alone is not enough. 
•        Check FDOT APL status and Buy America early. An APL listing does not guarantee Buy America compliance. 

Which Standards Should the Specification Name? 

Start with the standards, because they decide which products pass review. A specification that only says UL listed can let a product listed for the wrong circuit through. Three references come up most on ITS projects. 

1.      UL 1449 is the main safety standard for AC power surge protective devices (SPDs). Its third edition replaced the older term TVSS with SPD. Newer editions are in use, so name the current one.  
2.      UL 497B covers protectors for data communications and fire alarm circuits, including Ethernet data line protectors. Transtector’s ALPU-F140 and DPR-F140 are both listed to it. 
3.      NEMA TS 2 is a traffic controller assembly standard. ALPU-F140 is tested and compliant to it.  

The FDOT Approved Product List is a state approval list, not a standard. Section 4 of this blog covers it in more detail. State which listing applies to which circuit, plus the rating and the application. 

Indoor vs. Outdoor Protection: Where Does Each Device Go? 

Surges reach equipment through data and PoE lines, not only the power feed. A long Ethernet run to a camera carries lightning energy into the device. What the protector must withstand depends on where it mounts: inside a sealed cabinet or out on a pole. 

Outdoor field devices face rain, UV, temperature swings, salt, and dust. They need a weatherized housing, sealed cable entries, and a mount that works on a pole or wall. The ALPU-F140 is one example: pole or wall mount, weatherized grommet and gasket, and a shielded RJ-45. 

Indoor or in-cabinet devices sit inside a protected enclosure, so compact size and easy mounting matter most. The DPR-F140 is one example: DIN rail, wall, or rack mount, with a DIN clip that provides the ground connection.  

Layer the protection. Protect the cable where it enters the cabinet and again near the sensitive equipment it feeds.  

Ground first. A protector can only divert surge energy if it has a solid path to ground, so put the grounding approach in the specification.  

PoE++ Compatibility: What Should the Specification Say? 

Power over Ethernet sends power and data over one cable. A protector on that line must pass both cleanly and still stop surges. The faster and more powerful the link, the more closely the protector must match it. 

PoE comes in generations: 802.3af (PoE), 802.3at (PoE+), and 802.3bt (PoE++). PoE++ has two types. Type 3 delivers up to 60 W from the power source, and Type 4 delivers up to 90 W.  PTZ cameras and radios are common PoE++ loads. 

Match the protector to the line on three points: 

•        PoE type. Confirm the protector supports the type on the line: 802.3at, or 802.3bt Type 3 or Type 4. A protector rated for older PoE can fail or cause link problems on a PoE++ line. 
•        Data speed. Gigabit or 10 Gigabit. ALPU-F140 and DPR-F140 support Gigabit Ethernet and PoE++. 
•        Current rating. Compare it with the highest current the camera or radio draws. 

BABA and FDOT: Which Products Can You Specify? 

Two rules can take a product out of your specification before bidding starts. Check both while you’re still choosing products. 

FDOT Approved Product List (APL). On Florida DOT projects, a product must be on the Florida DOT Approved Product List  before the contractor can use it. Entries are grouped by numbered category, and surge protection sits under section 620, Grounding and Lightning Protection. 

1.      ALPU-F140 and DPR-F140 appear together on the APL for low voltage SPDs. 
2.      ALPU-F140 is cited as APL 620-004-012.  

Build America, Buy America (BABA). On January 14, 2025, FHWA published a final rule ending a decades-old waiver that exempted most manufactured products on federal-aid highway projects. ITS hardware and electrical equipment were among the items previously exempt. The rule phases in two requirements: 

3.      Projects obligated on or after October 1, 2025: final assembly must happen in the U.S. 
4.      Projects obligated on or after October 1, 2026: the U.S.-made share of component cost must exceed 55 percent. 

Treat them as two checks, not one. An APL listing does not guarantee BABA compliance, because some APL entries carry date-limited BABA notes. Confirm both on every project. 

Common Specification Mistakes to Avoid 

Six specification mistakes leave a circuit unprotected or let in a product that can’t handle the job. Check your draft against this list: 

1.      Naming a brand instead of requirements. A brand name tells bidders what to quote, not what to meet. List the standards, ratings, and mounting environment, and any qualified product can compete. 
2.      Protecting the power feed and skipping the data lines. Surges also travel down Ethernet. A camera on a long cable run stays exposed even when the cabinet's AC power is protected. 
3.      Leaving grounding out of the specification. A protector with a weak path to ground cannot divert a surge. Do not assume the cabinet is well grounded. Write the grounding requirement into the specification. 
4.      Skipping the ratings match. Check the protector's voltage, current, and data speed against the device it feeds. A PoE++ camera needs a protector rated for PoE++. 
5.      Ignoring the mounting environment. A pole-mounted protector sees rain, UV, and temperature swings. Require a weatherized housing and sealed cable entries. 
6.      Checking APL and BABA status last. Finding out at submittal that a product is ineligible forces a redesign and a schedule slip. Confirm both before the specification is issued. 

Transtector Data Line Surge Protectors for ITS: ALPU-F140 and DPR-F140 

Two Transtector data line surge protectors cover the outdoor and indoor cases from the previous sections. 

ITS Surge Protection Specification: Five Checks Before You Issue 

Before a specification goes to bid, confirm five things: 

1.      Standards. UL 1449 for AC power and UL 497B for data lines, each tied to its circuit. 
2.      Protection points. AC power, data, and PoE lines covered at the cabinet entry and near the equipment. 
3.      Ratings. Protector matched to the PoE type, data speed, and current rating. 
4.      Compliance. FDOT APL and BABA status confirmed for every product. 
5.      Grounding. The grounding approach written into the specification. 

For help with a specific project, contact a Transtector application engineer. 

Frequently Asked Questions (FAQs) 

What is a surge protective device (SPD)? 
A surge protective device (SPD) diverts surge energy away from connected equipment. A surge is a brief voltage spike, usually from lightning or large equipment switching on and off. An SPD works only with a solid path to ground, so grounding belongs in the specification. 

Which standards should an ITS surge protection specification name? 
An ITS surge protection specification should name UL 1449 for AC power SPDs and UL 497B for data line protectors. Add NEMA TS 2 where traffic controller assemblies are involved. Tie each listing to its circuit and state the rating and application, because UL listed alone does not say which circuit a product protects. 

Do PoE cameras and data lines need surge protection? 
Yes. Surges travel down Ethernet cables, not only power lines, and long outdoor runs to cameras and message signs are exposed. Protect the cable where it enters the cabinet and again near the equipment it feeds. Protecting AC power alone leaves PoE devices at risk. 

What PoE++ rating should an ITS surge protector have? 
The surge protector should support the PoE++ type on the line. Type 3 delivers up to 60 W from the power source and Type 4 up to 90 W. Also match the data speed, Gigabit or 10 Gigabit, and the current rating. A protector rated for older PoE can fail or cause link problems on a PoE++ line. 

Is FDOT APL approval the same as Buy America compliance? 
No. The FDOT Approved Product List is a state approval list, while Buy America is a federal requirement for federally funded projects. Some APL entries carry date-limited BABA notes, so confirm both for every project. 

What is the difference between indoor and outdoor surge protectors for ITS? 
Outdoor surge protectors need weatherized housing, sealed cable entries, and a pole or wall mount to withstand rain, UV, temperature swings, salt, and dust. Indoor surge protectors sit in a protected enclosure, so compact size and DIN rail, wall, or rack mounting matter most.