Mersen STXH240S05 ST-XH Series...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$559.96
$540.56
Mersen STXH240S05 ST-XH Series Type 1 Surge Protective Device, 240/120V

Mersen STXH240S05 ST-XH Series Type 1 Surge Protective Device, 240/120V

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Model: STXH240S05

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

$559.96
$540.56
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Mersen STXH240S05 ST-XH Series Type 1 Surge Protective Device, 240/120V

The Mersen STXH240S05 is a Type 1 Surge Protective Device from the ST-XH Series, engineered for 240/120V L-L split phase electrical systems. Rated with a Voltage Protection Rating (VPR) of 600V L-N and a Maximum Continuous Operating Voltage (MCOV) of 150V L-N, this SPD delivers 50 kA of surge suppression capacity with an LED indication system for at-a-glance status monitoring. Housed in a NEMA 4X non-metallic polycarbonate enclosure, it is built for reliable panel-mount installation in demanding electrical environments.

Key Features

  • System Configuration: 240/120V L-L split phase system for standard commercial and industrial power distribution.
  • Voltage Protection Rating (VPR): 600V L-N and 1000V L-G for dependable clamping performance during surge events.
  • Maximum Continuous Operating Voltage (MCOV): 150V L-N and 300V L-G, matched to the connected system voltage.
  • Nominal Discharge Current (In 8/20): 20 kA rated surge current handling for repeated transient events.
  • Durable Construction: Polycarbonate housing in a NEMA 4X non-metallic enclosure for corrosion resistance.
  • LED Indication System: Built-in LED indicator provides quick visual confirmation of protection status.
  • Installation: Panel mount configuration for AC systems operating at 50/60 Hz.
  • Protection Modes: L-N and L-G modes covered for comprehensive circuit protection.

Certifications & Compliance

  • RoHS Compliant

Technical Specifications

  • Ac Or Dc: AC
  • Enclosure Nema Type: 4X Non-Metallic
  • Format: STXH
  • Frequency Hz: 50/60 Hz
  • Housing Material: Polycarbonate
  • Indication System: Yes
  • Indication System Type: LED
  • Installation Mounting: Panel Mount
  • Mcov L G: 300 V
  • Mcov L N: 150 V
  • Nominal Discharge Current In 8 20: 20 kA
  • Product Height: 3.22 in
  • Product Length: 3.2 in
  • Product Weight: 0.8 lb
  • Product Width: 1.85 in
  • Protection Modes: L-N, L-G
  • Rohs Compliant: Yes
  • System Configuration: Split Phase
  • Vpr L G: 1000 V
  • Vpr L N: 600 V

Typical Applications

  • Commercial and Industrial Electrical Panels
  • 240/120V Split Phase Service Entrances
  • Panelboard Surge Protection
  • Wash-down and Corrosive Environments (NEMA 4X)
  • Renovation and New Construction Electrical Systems

Why Mersen?

Mersen's ST-XH Series pairs a rugged NEMA 4X polycarbonate enclosure with dependable VPR and MCOV performance to protect connected loads on 240/120V split phase systems. The built-in LED indication system and RoHS compliant construction support reliable, code-conscious surge protection for professional electrical installations.

Manufacturer Resources

Mersen Product Catalog

Product Specs

Ac Or Dc:
AC
Enclosure Nema Type:
4X Non-Metallic
Format:
STXH
Frequency Hz:
50/60 Hz
Housing Material:
Polycarbonate
Indication System:
Yes
Indication System Type:
LED
Installation Mounting:
Panel Mount
Mcov L G:
300 V
Mcov L N:
150 V
Nominal Discharge Current In 8 20:
20 kA
Product Height:
3.22 in
Product Length:
3.2 in
Product Weight:
0.8 lb
Product Width:
1.85 in
Protection Modes:
L-N, L-G
Rohs Compliant:
Yes
System Configuration:
Split Phase
Ul Spd Type:
Type 1
Vpr L G:
1000 V
Vpr L N:
600 V
Department:
Electrical
Product Group:
Wiring Devices
Product Type:
Surge Protective Device
Product Subgroup:
Panelboards & Load Centers

Mersen STXH240S05 – Frequently Asked Questions

1) Will the Mersen STXH240S05 work on a 240/120V single phase panel?
Yes. The STXH240S05 is built for 240/120V split phase (single phase three wire) AC systems at 50/60 Hz, with an MCOV of 150V line to neutral and 300V line to ground. It is not for 208Y/120V or 480Y/277V three phase service; those need a different voltage rating.
2) Can this Mersen SPD be installed on the line side of the main breaker?
Yes, that is what a Type 1 device is for. The STXH240S05 carries a UL SPD Type 1 rating, so it can be connected on the line side of the service disconnect as well as on the load side, which makes it the usual pick for service entrance protection on a 240/120V split phase service.
3) Is this surge protector OK outdoors or in a wash-down area?
The enclosure is NEMA 4X non-metallic polycarbonate, so it stands up to hose-down and corrosive atmospheres, which is why it suits food processing, car wash, water treatment and similar plants. A painted steel NEMA 1 unit would not be appropriate in those rooms.
4) How is this different from an Eaton BR breaker-style surge device or a Square D Surgelogic unit?
The Mersen STXH240S05 is an externally mounted Type 1 device in a NEMA 4X polycarbonate enclosure for 240/120V split phase. The Eaton BRNSURGE10 is a two-pole 10 kA surge device that plugs into a BR Series loadcenter, so it only fits BR panels. The Square D Surgelogic EMD25 is rated 500 kA on 208Y/120V three phase four wire, which is a different system voltage and a much higher capacity for larger three phase distribution gear.
5) What should I use instead of the Mersen STXH240S05 on a 208Y/120V three-phase four-wire service?
The Mersen STXH240S05 is built for 240/120V split phase systems, with 150 V MCOV L-N and 300 V MCOV L-G, so it is matched to a single-phase three-wire service rather than a wye three-phase one. For a 208Y/120V three-phase four-wire panel, the Square D Surgelogic surge protective device is rated 500kA at 208Y/120V three-phase four-wire and suits that configuration directly.
6) Is there a simpler breaker-panel surge option than the Mersen STXH240S05?
Yes. The Eaton BRNSURGE10 is a BR Series two-pole 10kA surge protective device that installs into a BR loadcenter breaker space. The Mersen STXH240S05 is a separate panel-mount unit in a NEMA 4X non-metallic polycarbonate enclosure with an LED indication system, wired externally to the panel rather than occupying breaker poles.
7) What surge current can the Mersen STXH240S05 handle?
The device is rated 50 kA of surge capacity with a nominal discharge current (In, 8/20 us) of 20 kA, so it is sized for repeated transient events rather than a one-shot hit. Clamping is 600V VPR line to neutral and 1000V line to ground.
8) How much space do I need to mount the Mersen STXH240S05 next to a panelboard?
It is a compact panel mount unit measuring 3.22 x 3.2 x 1.85 inches and weighing 0.8 lb, so it mounts to a knockout or adjacent surface without needing its own wall bracket. Allow room for the conductor leads to run into the panel as short and straight as practical.
9) How do I know if the surge protector is still protecting after a storm?
There is a built-in LED indication system on the front of the unit. A glance tells maintenance whether the protection modes are still intact, so a facility tech can check it during rounds without opening the panel or metering anything.
10) Which modes does the Mersen ST-XH SPD actually protect?
Protection is provided line to neutral and line to ground (L-N and L-G), rated 600V VPR L-N and 1000V VPR L-G. If your spec calls for all seven modes including N-G, this two-mode configuration will not meet it.
11) For a wash-down or corrosive area, does the Eaton BRNSURGE10 work the same as the Mersen STXH240S05?
They are not interchangeable for that environment. The Mersen STXH240S05 carries a NEMA 4X non-metallic polycarbonate housing specifically for corrosion resistance and wash-down locations, and it is a UL Type 1 device that can be applied on the line side of the main. The Eaton BRNSURGE10 is a BR Series two-pole unit that mounts inside a BR loadcenter and depends on that loadcenter's own enclosure rating.
12) Is the Mersen STXH240S05 RoHS compliant for our institutional spec?
Yes, the ST-XH unit is RoHS compliant, which covers the restricted-substances line item that shows up on a lot of government and healthcare submittals.
How fast can I get the Mersen STXH240S05 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 STXH240S05 come with a warranty?
Absolutely. The Mersen STXH240S05 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 STXH240S05?
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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