Eaton LPJ-35SP Class J Time-Delay Fuse

Overview

Eaton LPJ-35SP is a 35 ampere, Bussmann series Low-Peak Class J dual-element time-delay fuse engineered for demanding industrial power distribution and motor circuit protection duties. Rated 600Vac/300Vdc with an exceptional interrupting rating of 300kA at 600Vac, the Eaton LPJ-35SP combines true current-limiting short-circuit interruption with a time-delay characteristic tuned for motor starting and transformer inrush, making it a preferred choice for panelboards, motor control centers, and branch circuit protection across process plants, utilities, and commercial facilities.

As the official authorized partner and exclusive regional representative for Eaton, Seven Star LLC proudly supplies the LPJ-35SP and the full Bussmann Low-Peak LPJ_SP fuse family to industrial and commercial customers throughout the Sultanate of Oman and the wider GCC, backed by genuine factory-sourced stock, technical application support, and full manufacturer warranty coverage — a level of assurance grey-market resellers in the region cannot match.

Operating Principle

The Eaton LPJ-35SP uses a dual-element design that separates overload protection from short-circuit protection within a single cartridge body. A spring-loaded thermal element handles sustained low-level overloads — such as the temporary inrush current drawn by a motor at start-up — and is calibrated to delay operation for a minimum of 10 seconds at 500% of rated current, preventing nuisance blowing during normal motor acceleration or transformer energization. A separate silver short-circuit element, filled with granular quartz sand, responds instantaneously to fault currents, current-limiting the let-through energy before it can reach damaging peak levels.

Because the short-circuit element is current-limiting by design, the LPJ-35SP clips the available fault current waveform well below its natural peak, protecting downstream conductors, bus bars, and equipment from the destructive thermal and magnetic forces of a bolted fault. This dual-element, current-limiting behavior means the fuse tolerates the everyday inrush of motors and transformers without derating the circuit, while still interrupting a 300kA fault safely and predictably — a combination that ordinary single-element fuses and many circuit breakers cannot achieve in the same footprint.

Engineering Design of the Eaton LPJ-35SP

Physically, the Eaton LPJ-35SP is built in the compact Class J cylindrical cartridge format, measuring 1.06 x 2.38 inches, with a rugged melamine body and silver-plated ferrule terminals that provide low-resistance, high-integrity contact inside standard Class J fuse blocks, disconnect switches, and panelboard mains. The Class J form factor is rejection-style, meaning it physically cannot be installed in a lower-rated fuse clip, eliminating the risk of an under-rated fuse being fitted in a high fault-current application during maintenance or replacement.

Field installation is straightforward: the ferrule ends drop directly into J-rated clips or blocks without special tooling, and Eaton offers an optional visual indicator variant (LPJ-35SPI) that trips a mechanical flag on element operation, allowing maintenance staff to identify a blown fuse at a glance without powering down the panel. The Low-Peak family also maintains a 2:1 selective coordination ratio, so upstream and downstream LPJ fuses can be sized to isolate only the affected branch during a fault, keeping the rest of the distribution system energized.

Key Features

The Eaton LPJ-35SP Class J time-delay fuse delivers a combination of protective performance and installation flexibility that makes it a standard specification across industrial and commercial panelboards. Engineers selecting the Eaton LPJ-35SP for a new or retrofit installation benefit from the following key features:

• Delivers a 300kA interrupting rating at 600Vac, giving reliable protection even on high fault-current utility services and generator-backed distribution boards.
• Provides a minimum 10-second time-delay at 500% rated current, allowing motors and transformers to start without nuisance fuse operation.
• Uses true current-limiting short-circuit interruption to reduce let-through energy and protect downstream conductors, bus work, and equipment.
• Features a rejection-style Class J cartridge body that prevents installation of lower-rated, non-current-limiting fuses in the same clip.
• Supports 2:1 selective coordination within the Low-Peak family for cleaner fault isolation and improved system uptime.
• Offers dual-rated 600Vac/300Vdc operation, extending applicability to DC distribution and battery-backed systems.
• Available in an indicating variant (LPJ-35SPI) for rapid visual identification of a blown fuse during troubleshooting.
• Carries UL Class J listing and CSA certification, satisfying North American and internationally recognized code requirements for critical circuit protection.

Industrial Applications

The Eaton LPJ-35SP is widely specified for motor circuit protection, transformer primary protection, HVAC and chiller plant feeders, machinery disconnects, and general power panelboard mains where both high fault-current interruption and tolerance for motor starting inrush are required simultaneously. In GCC industrial facilities running large pumps, compressors, and rotating equipment, the dual-element time-delay characteristic prevents the false trips that plague simpler fuse types during routine start-stop cycling, reducing unplanned downtime and maintenance callouts.

As the officially authorized partner for Eaton, Seven Star LLC distributes the LPJ-35SP and related Bussmann Low-Peak fuses to district cooling plants, RO desalination facilities, oil and gas support infrastructure, and commercial and hospitality developments across Muscat, and to industrial users operating within the Sohar and Salalah economic zones. Facility engineers and procurement teams across Oman and the GCC rely on Seven Star LLC for genuine Eaton Bussmann stock, fast regional fulfillment, and technical guidance on fuse sizing and selective coordination for panelboards, motor control centers, and switchgear line-ups.

Technical Specifications

The table below summarizes the primary electrical and physical specifications of the Eaton LPJ-35SP, confirming why the Eaton LPJ-35SP is specified wherever both current-limiting protection and motor-starting tolerance are required.

Call To Action

To order the Eaton LPJ-35SP, Seven Star LLC supports formal RFQ submissions for the Eaton LPJ-35SP Class J time-delay fuse, maintains regional warehouse stock for fast delivery across Oman and the GCC, and provides the full Eaton Bussmann technical datasheet on request for engineering review and panel design. As the authorized partner for Eaton in Oman and the GCC, Seven Star LLC’s instrumentation and electrical protection division is available to confirm fuse sizing, selective coordination, and lead times — contact our team directly to place an order or request a formal quotation for the LPJ-35SP or any other Bussmann Low-Peak fuse.