Mersen STLC240S025 Type 1 Surg...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$445.40
$419.13
Mersen STLC240S025 Type 1 Surge Protective Device, 240/120V 25kA

Mersen STLC240S025 Type 1 Surge Protective Device, 240/120V 25kA

(No reviews yet) Write a Review

Model: STLC240S025

In Stock (leaves warehouse same day if ordered before 3pm ET)

$445.40
$419.13
Adding to cart… The item has been added
Free Shipping on orders over $199
We price match and offer bulk discounts! Click Add to Quote. It's quick and easy.
✨
Earn points with this purchase! You can redeem points for giftcards, iPads, XBox's and more. View Rewards
Free Keying on all locks
You may also like

Mersen STLC240S025 Type 1 Surge Protective Device, 240/120V 25kA

The Mersen STLC240S025 is a Type 1 surge protective device (SPD) from the STLC Series, engineered for 240/120V split-phase electrical systems with a 25kA surge current rating. Designed for direct bus bar installation, this AC-rated SPD (50/60 Hz) integrates an LED indication system for immediate visual status monitoring and includes a neutral wire connection for split-phase configurations. Housed in durable plastic construction and RoHS compliant, the STLC240S025 delivers dependable transient voltage protection for commercial and industrial power distribution equipment.

Key Features

  • Type 1 SPD: STLC Series surge protective device rated 240/120V for split-phase system configurations.
  • Surge Protection Rating: 25kA surge current capacity with a Nominal Discharge Current In (8/20) of 10 kA for robust transient suppression.
  • LED Indication System: Built-in LED indicator provides at-a-glance confirmation of SPD operational status.
  • Neutral Wire: Includes a dedicated neutral wire connection suited to split-phase installations.
  • Bus Bar Installation: Mounts directly to the bus bar for streamlined integration into panelboards and load centers.
  • Voltage Protection Ratings: MCOV of 300 V (L-L) and 150 V (L-N); Vpr of 1000 V (L-L) and 600 V (L-N).
  • AC Rated: Operates on AC power at 50/60 Hz.
  • Durable Construction: Plastic housing for reliable field performance.

Certifications & Compliance

  • RoHS Compliant

Technical Specifications

  • Ac Or Dc: AC
  • Frequency Hz: 50/60 Hz
  • Housing Material: Plastic
  • Indication System: Yes
  • Indication System Type: LED
  • Installation Mounting: Bus Bar Installation
  • Mcov L L: 300 V
  • Mcov L N: 150 V
  • Nominal Discharge Current In 8 20: 10 kA
  • Product Height: 2.36 in
  • Product Length: 3.18 in
  • Product Weight: 0.5 lb
  • Product Width: 1.99 in
  • Rohs Compliant: Yes
  • System Configuration: Split Phase
  • Vpr L L: 1000 V
  • Vpr L N: 600 V

Typical Applications

  • Commercial and Industrial Electrical Panels
  • Split-Phase Power Distribution Systems
  • Bus Bar-Mounted Surge Protection
  • Panelboard and Load Center Protection
  • New Construction and Retrofit Panel Upgrades

Why Mersen?

Mersen's STLC Series surge protective devices pair LED status indication with RoHS-compliant plastic housing to deliver dependable transient voltage protection for split-phase electrical systems. With a 25kA surge rating, defined MCOV and Vpr protection levels, and straightforward bus bar installation, the STLC240S025 supports code-compliant, reliable surge protection for professional electrical work.

Manufacturer Resources

Mersen Product Catalog

Product Specs

Ac Or Dc:
AC
Format:
STLC
Frequency Hz:
50/60 Hz
Housing Material:
Plastic
Indication System:
Yes
Indication System Type:
LED
Installation Mounting:
Bus Bar Installation
Mcov L L:
300 V
Mcov L N:
150 V
Nominal Discharge Current In 8 20:
10 kA
Product Height:
2.36 in
Product Length:
3.18 in
Product Weight:
0.5 lb
Product Width:
1.99 in
Rohs Compliant:
Yes
System Configuration:
Split Phase
Ul Spd Type:
Type 1
Vpr L L:
1000 V
Vpr L N:
600 V
Department:
Electrical
Product Group:
Wiring Devices
Product Type:
Surge Protective Device
Product Subgroup:
Panelboards & Load Centers

Mersen STLC240S025 – Frequently Asked Questions

1) Will the Mersen STLC240S025 work on a 208Y/120V three-phase panel?
No. The STLC240S025 is built for 240/120V split-phase systems, and its MCOV is 300 V line-to-line and 150 V line-to-neutral. A 208Y/120V three-phase, four-wire panel needs a three-phase SPD instead, such as the Square D Surgelogic unit rated 208Y/120V 3-phase 4-wire. Putting a split-phase device on the wrong system configuration is the most common misapplication here.
2) What does Type 1 mean for where I can install this Mersen surge protector?
Type 1 is the UL SPD type on the STLC240S025, meaning it is permitted on the line side of the service disconnect as well as on the load side. That is what lets an electrician land it at the service entrance without an added overcurrent device, where a Type 2 unit would have to sit downstream of the main breaker.
3) How does the Mersen STLC240S025 mount in a panelboard?
It mounts directly to the bus bar rather than clipping into a breaker space, and it ships with a neutral wire for the split-phase connection. Plan for a device roughly 3.18 x 2.36 x 1.99 inches at 0.5 lb inside the gutter or on the bus, and route the leads as short and straight as you can, since lead length adds to let-through voltage.
4) What is the difference between the Mersen STLC240S025 and the Square D Surgelogic EMD25 surge protective device?
They protect different service types. The Mersen STLC240S025 is configured for split-phase 240/120V service and mounts directly to the bus bar. The Square D Surgelogic unit is rated 208Y/120V 3-phase 4-wire at 500kA, so it suits a wye three-phase panel rather than a single-phase residential-style or light commercial split-phase panel. Match the device to the system configuration on the panel schedule: a split-phase panel takes the STLC240S025, a 208Y/120V three-phase panel takes the Surgelogic.
5) Can I use an Eaton BRNSURGE10 instead of a Mersen STLC240S025 in a split-phase panel?
Both are aimed at two-pole single-phase panel protection, but they are not interchangeable hardware. The Eaton BRNSURGE10 is a two-pole 10kA device built for Eaton BR Series load centers, so it seats in BR breaker spaces. The Mersen STLC240S025 is a Type 1 SPD rated 25kA that lands on the bus bar with a neutral connection for 240/120V split-phase service and carries LED status indication. If the panel is an Eaton BR load center, the BR-specific unit is the drop-in; if you are adding surge protection to a panelboard by bus bar connection, the Mersen is the one to spec.
6) What is the difference between the 25kA surge rating and the 10kA nominal discharge current on this SPD?
Two different numbers that get confused constantly. The 25kA is the surge current capacity per mode on the STLC240S025. The 10 kA figure is the Nominal Discharge Current In at an 8/20 microsecond waveform, which is the repeatable surge the device is tested to survive multiple times. Specifiers and inspectors usually want the In value, so 10 kA is the number to put on the submittal.
7) What are the voltage protection ratings I need for a submittal on the Mersen STLC240S025?
Vpr is 1000 V line-to-line and 600 V line-to-neutral, with MCOV of 300 V L-L and 150 V L-N. Those four values are what an engineer checks against the equipment being protected, and the 150 V L-N MCOV confirms it sits comfortably above a nominal 120 V leg.
8) How do I tell if this Mersen SPD has failed?
The STLC240S025 carries a built-in LED status indicator. A quick look at the light during a panel inspection tells a maintenance tech whether the protection modules are still live, so you can add it to a walk-through route rather than pulling the device to test it.
9) Is there a breaker-style surge protector instead of a bus bar mount for a residential-style load center?
Yes, if a breaker-space device suits the panel better, the Eaton BRNSURGE10 is a two-pole 10kA SPD in the BR Series. It plugs into BR breaker spaces rather than landing on the bus the way the Mersen STLC240S025 does. Pick by panel: bus bar mounting for the Mersen, BR breaker interior for the Eaton.
10) Which single-phase surge device has the higher surge current rating, the Mersen STLC240S025 or the Eaton BRNSURGE10?
The Mersen STLC240S025 is rated 25kA with a nominal discharge current In (8/20) of 10 kA, while the Eaton BRNSURGE10 is a two-pole 10kA device. The Mersen also publishes voltage protection ratings of 1000 V line-to-line and 600 V line-to-neutral, which is the number most plan reviewers ask for on a spec sheet. Choose based on what the drawing calls out for surge current capacity and VPR, and on whether the panel accepts a bus bar connection or an Eaton BR breaker space.
11) For standardizing surge protection across a multi-building property, when would I pick the Mersen STLC240S025 over the Square D Surgelogic?
Use the Mersen STLC240S025 wherever the service is 240/120V split-phase - typical of individual units, small commercial panels and load centers - since it is a Type 1 SPD with a neutral wire and bus bar mounting, in a compact 3.18 by 1.99 by 2.36 inch plastic housing weighing 0.5 lb. Use the Square D Surgelogic 208Y/120V 3-phase 4-wire unit at the three-phase house panels or main distribution. Most mixed portfolios end up carrying both rather than one part number.
12) Does the Mersen STLC240S025 work on 50 Hz power?
It is an AC device rated 50/60 Hz, so it applies on either 50 Hz or 60 Hz split-phase systems. It is not a DC SPD, so do not use it on solar DC strings or battery buses.
13) Is the Mersen STLC240S025 RoHS compliant for a government or institutional spec?
Yes, the STLC240S025 is RoHS compliant, and the housing is plastic. That is the compliance statement carried on the device.
14) What exact part number should I order for a 240/120V 25kA Mersen STLC surge device?
STLC240S025 is the Mersen manufacturer part number, from the STLC series. Ordering by that number gets the Type 1, 240/120V split-phase, 25kA bus bar unit with LED indication.
How fast can I get the Mersen STLC240S025 delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Mersen STLC240S025 come with a warranty?
Absolutely. The Mersen STLC240S025 is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Mersen STLC240S025?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the Mersen STLC240S025 from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support, and rewards on every order. Our team is always ready to help you choose the right product for your project.
!