Mersen ST-XR Series Type 1 Sur...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$619.13
Mersen ST-XR Series Type 1 Surge Protective Device, 240V, 50 kA

Mersen ST-XR Series Type 1 Surge Protective Device, 240V, 50 kA

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Model: STXR240D05

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

$619.13
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Mersen ST-XR Series Type 1 Surge Protective Device, 240V, 50 kA

The Mersen ST-XR Series Type 1 Surge Protective Device (SPD) is a UL1449 5th Edition-listed surge arrestor replacement built with TPMOV® technology for safe, reliable performance. Rated 240V L-L, this compact SPD offers a Voltage Protection Rating (VPR) of 1500V L-L (1200V L-G), an MCOV of 640V L-L (320V L-G), and a 50 kA surge rating, with flexible line- or load-side installation for branch panel or individual equipment protection. Its compact, panel-mount design makes it a practical, code-compliant upgrade wherever legacy surge arrestors need to be replaced with modern, safer surge protection technology.

Key Features

  • Durable Enclosure: NEMA 4X non-metallic polycarbonate housing resists corrosion in demanding electrical environments.
  • Flexible Mounting: Panel Mount installation supports line or load connection for branch panel and individual equipment protection.
  • Voltage Protection: VPR of 1500V L-L / 1200V L-G safeguards connected equipment from transient surges.
  • MCOV Rating: Maximum Continuous Operating Voltage of 640V L-L / 320V L-G matches 240V L-L system requirements.
  • Surge Capacity: Rated 50 kA with a Nominal Discharge Current (In) of 20 kA (8/20) for dependable transient suppression.
  • 3-Phase Delta Configuration: Engineered for AC systems operating at 50/60 Hz.
  • LED Indication: Built-in LED indication system provides at-a-glance protection status.
  • TPMOV® Technology: A safer alternative to standard MOV-based surge protection designs, engineered into the compact STXR format.

Certifications & Compliance

  • UL Listed, UL1449 5th Edition Type 1 SPD
  • RoHS Compliant

Technical Specifications

  • Indication System Type: LED
  • Indication System: Yes
  • ROHS Compliant: Yes
  • AC or DC: AC

Typical Applications

  • Commercial and Industrial Electrical Panels
  • Branch Panel Surge Protection
  • Individual Equipment Protection
  • 3-Phase Delta Distribution Systems
  • Panel Mount Installations
  • Replacement for Outdated Surge Arrestors

Why Mersen?

Mersen's ST-XR Series combines UL1449 5th Edition compliance, TPMOV® technology, and a rugged NEMA 4X polycarbonate enclosure to deliver dependable, code-compliant surge protection for professional electrical installations. With clear LED status indication and RoHS-compliant construction, the ST-XR Series is engineered for long-term reliability in demanding commercial and industrial environments. As part of the broader Mersen Surge-Trap STX product line, the ST-XR Series gives electrical contractors and facility engineers a trusted, standards-based path to modernizing surge protection on 3-Phase Delta AC systems.

Manufacturer Resources

Product Specs

Frequency (Hz):
50/60 Hz
Nominal Discharge Current In 8 20:
20 kA
ROHS Compliant:
Yes
list_batch:
MERSEN-20260825
AC or DC:
AC
MCOV L-L:
640 V
Product Group:
Circuit Protection
Department:
Electrical
Indication System:
Yes
Product Type:
Surge Protective Device
Product Subgroup:
Surge Protection

Mersen STXR240D05 – Frequently Asked Questions

1) Can I install the Mersen ST-XR surge protective device on the line side of the main breaker?
Yes. The ST-XR is a UL1449 5th Edition Type 1 SPD, so it can be connected on the line side (ahead of the main overcurrent device) or on the load side. That makes it workable either as branch panel protection or wired to a single piece of equipment. Type 2 devices are load-side only, which is the practical reason to pick a Type 1 here.
2) Is the 240V Mersen Surge-Trap right for a 3-phase delta system or a 120/240 single phase panel?
The STXR240D05 is built for 3-phase delta AC distribution at 240V line-to-line, 50/60 Hz. The MCOV of 640V L-L (320V L-G) is set to match that 240V delta system. For a residential-style 120/240V single-phase load center, a plug-on or breaker-style unit like the Eaton BRPSURGE or BRNSURGE10 is the type that belongs in that panel.
3) I need to replace an old surge arrestor in a commercial panel. Is the ST-XR a direct code-compliant swap?
That is exactly what the ST-XR is built for. It is a UL1449 5th Edition listed surge arrestor replacement using TPMOV technology, which is the safer modern alternative to a bare MOV design, and the compact panel-mount format is meant to drop into the space a legacy arrestor occupied. Match the system first: the 240V unit is for 240V L-L delta.
4) What is the difference between the Mersen ST-XR Series surge protective device and the Eaton BRNSURGE10 breaker-style SPD?
They solve surge protection at different points. The Mersen ST-XR Series is a Type 1 SPD rated 240V L-L with a 50 kA surge rating, a 20 kA nominal discharge current (8/20), a 640V L-L MCOV, and a panel-mount NEMA 4X polycarbonate enclosure that can be wired line side or load side. The Eaton BRNSURGE10 is a BR Series two-pole 10 kA device that occupies breaker spaces inside a BR loadcenter, so it is chosen when the protection has to live inside the panel interior rather than mount to it.
5) I have a residential BR panel with plug-on neutral - is the Mersen ST-XR the right surge device, or should I use the Eaton BRPSURGE?
For a plug-on neutral BR loadcenter, the Eaton BRPSURGE is the device built to that interior - it is a Type BR 2-pole plug-on neutral SPD that snaps onto the bus. The Mersen ST-XR Series is a panel-mount Type 1 SPD rated 240V L-L that lands on conductors rather than a plug-on bus, so it suits branch panel or individual equipment protection in commercial and industrial gear and is commonly used where an outdated surge arrestor is being replaced.
6) How does the Mersen ST-XR compare to the Square D Surgelogic EMD25 for a 208Y/120V three-phase service entrance?
The Square D Surgelogic EMD25 is specified for 208Y/120V 3-phase 4-wire systems with a 500 kA surge rating, which is the configuration and capacity usually wanted at a service entrance on a wye system. The Mersen ST-XR Series is a Type 1 SPD engineered for 3-phase delta AC systems at 50/60 Hz, rated 240V L-L with a 50 kA surge rating and a VPR of 1500V L-L / 1200V L-G. Match the device to the system configuration first: delta versus wye determines which of the two fits.
7) What does the 50 kA rating on the Mersen ST-XR actually buy me, and how does it compare to a 500 kA panel SPD?
50 kA is the surge current rating, with a nominal discharge current (In) of 20 kA on the 8/20 waveform. That suits branch panel or single-equipment duty rather than service entrance work. If you are protecting a main switchboard on a 208Y/120V 3-phase 4-wire service, the Square D Surgelogic unit we carry is rated 500kA and is the heavier-duty choice for that location.
8) Will the Mersen Surge-Trap hold up mounted outdoors or in a washdown area?
The enclosure is NEMA 4X non-metallic polycarbonate, so it handles corrosive and wet-location duty that a steel housing would rust out in. It is a panel-mount device, so it bolts to the panel or enclosure rather than sitting in its own free-standing cabinet.
9) What voltage options does the Mersen Surge-Trap come in, and what are the part numbers?
Two: the 240V unit, part number STXR240D05, and a 480V unit, part number STP480YN07M. Order by system voltage at the panel you are feeding, since the MCOV is matched to the system, not field adjustable.
10) What is the let-through voltage on the Mersen 240V SPD, and is it tight enough for sensitive equipment?
The Voltage Protection Rating is 1500V L-L and 1200V L-G. That is the measured limited voltage the downstream gear sees on a surge, which is what you compare against the withstand of the equipment you are protecting. Paired with a 20 kA nominal discharge current, it is intended for branch panel feeds and individual equipment, not as the only device on a service entrance.
11) Is the Eaton BRNSURGE10 a direct replacement for a Mersen ST-XR on a 480V feeder?
No. The Mersen ST-XR family covers higher-voltage work - the 240V device is the STXR240D05 and a 480V option is offered as STP480YN07M. The Eaton BRNSURGE10 is a BR Series two-pole 10 kA device intended for BR loadcenters, not a 480V panel-mount equivalent, so it is not an interchange for a 480V feeder application.
12) How do I know the Mersen SPD is still protecting after a surge event?
There is a built-in LED indication system on the unit, so protection status is readable at a glance during a walk-through. No auxiliary monitoring module or dry contact is needed to see whether it is still live.
13) Is the Mersen ST-XR RoHS compliant for a spec that requires it?
Yes, the ST-XR Series is RoHS compliant, and it carries a UL Listing to UL1449 5th Edition as a Type 1 SPD. Both are useful on institutional and government submittals where the hardware schedule calls out compliance.
14) Does this Mersen surge device work on DC systems or 50 Hz power?
AC only. The ST-XR is rated for AC systems at 50/60 Hz, so it works on both 60 Hz North American and 50 Hz installations, but it is not a DC surge protector.
15) Do any of these surge devices give a visible status indicator like the Mersen ST-XR?
The Mersen ST-XR Series carries a built-in LED indication system so protection status can be read at a glance during a panel walkthrough. Among the comparable devices, the Eaton BRNSURGE10 and BRPSURGE are BR Series panel-interior devices and the Square D Surgelogic EMD25 is a Surgelogic three-phase unit; if diagnostic status is part of your PM routine, confirm the indication arrangement against the specific model you are standardizing on.
How fast can I get the Mersen STXR240D05 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 STXR240D05 come with a warranty?
Absolutely. The Mersen STXR240D05 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 STXR240D05?
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
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