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Grey rectangular surge protector enclosure, 2.81 inches deep

Mersen

Mersen STP240S07 Surge Protection Device 120/240V AC 2 Poles 3 Wires 75 kA

SKU CH-C9PP-NEVF8

A 120/240 V AC surge protector rated at 75 kA for single-phase, two-pole, three-wire installations

  • Product typePower Quality & Distribution
  • Protects 120/240 V AC circuits with 75 kA surge capacity
  • Two-pole, three-wire design handles single-phase power distribution
  • NEMA 1 rated polyethylene terephthalate enclosure suits indoor installation
  • Compact 2.81 in depth fits standard electrical boxes
  • Prop 65 listed for cancer and reproductive-hazard awareness

Surge Protection Device 120/240V AC

The Mersen STP240S07 is a surge protection device rated for 120/240V AC single-phase systems. It uses a two-pole, three-wire configuration to guard connected equipment against transient overvoltages. The unit is built in a grey non-metallic enclosure made from polyethylene terephthalate with a NEMA 1 rating. It is suited for residential or light-commercial panels where basic surge suppression is required.

75 kA surge current capacity

The device handles a maximum surge current of 75 kA, providing a high level of energy diversion during sustained overvoltage events. Its power quality and distribution design helps maintain consistent clamping performance across repeated strikes rather than degrading after a single large impulse. The polyethylene terephthalate enclosure resists environmental stress while the NEMA 1 rating ensures protection against incidental contact. This makes it reliable for continuous service in standard indoor environments.

Compact 2.81 in depth for panel mounting

Installation is straightforward thanks to the shallow 2.81 in depth, which fits many existing panel boards without extensive modification. The non-metallic housing reduces weight and eliminates grounding concerns associated with metal enclosures. A common issue arises when installers overlook the need for a dedicated three-wire connection, which is essential for proper operation. Ensuring correct phasing and secure terminations avoids nuisance tripping or reduced protection.

How it compares

Measured against everything we stock in Electrical Enclosures & Cabinets, at today’s prices. Recalculated every night.

Price $204.99
Pricier than about 88% of the 1,411 comparable items (median $39.99).

Specifications

Product
Brand nameMERSEN
Product typePower Quality & Distribution

Questions about this item

How much heat or noise does the 75 kA surge protector produce during continuous operation?

The device is a passive surge protection unit with no moving parts or active cooling, so it generates no audible noise and negligible heat while installed in a NEMA 1 enclosure.

What existing electrical infrastructure is required to install this 2-pole 3-wire unit?

A single-phase 120/240 V AC service with two hot conductors, one neutral and a grounding conductor, plus space in a panel for a 2.81 in deep NEMA 1 enclosure.

Will this protector coordinate with older panel breakers rated below 75 kA?

Yes, the 75 kA maximum surge current rating allows it to clamp transients before they reach downstream breakers, regardless of the breakers' own interrupting ratings.

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