Littelfuse has expanded its Shock Block industrial GFCI lineup with the SB4000, a compact ground-fault circuit interrupter designed for systems with full load currents up to 30A. The unit supports single-phase, split-phase, three-phase, and 4-wire installations operating from 208 V to 240 V, targeting industrial equipment, commercial kitchens, HVAC systems, and pool or spa installations where electrical protection requirements overlap with wet or washdown conditions.
The SB4000 is a Class A GFCI intended for personnel protection in higher-current industrial and OEM environments. It sits inline with the load circuit and disconnects power when a ground fault is detected, helping installations comply with NEC 210.8 requirements in retrofit and maintenance projects where adding protection to existing panels can become awkward.
Compact GFCI Protection for Industrial Retrofit Work
One of the more practical aspects of the SB4000 is its panel-agnostic installation approach. Littelfuse has avoided the use of external flying leads, instead using a more compact enclosure and configurable knockout positioning to simplify cabinet integration and retrofit work. That becomes relevant in older commercial or industrial systems where panel layouts, conduit entry, and enclosure space rarely match modern protection hardware particularly well. The device is intended for applications where equipment already exists in the field and electrical protection needs to be added without redesigning the surrounding system.
The enclosure itself is rated IP69K and NEMA 4X for outdoor use. That gives the unit protection against moisture ingress and high-temperature washdown conditions commonly found in food production equipment and industrial processing areas.
Built-In Neutral Protection and Harmonic Filtering
SB4000 models with neutral-wire connections include grounded-neutral protection compliant with UL 943 requirements. The device also incorporates harmonic filtering intended to reduce nuisance tripping in electrically noisy environments where variable-speed drives, compressors, or switching equipment may already be present on the line. The protection circuit uses a fixed 6 mA trip level to meet UL 943 personnel protection requirements, while the inverse time detection behavior helps avoid unnecessary shutdowns during short-duration transient conditions.
The SB4000 is also compliant with UL 1998, the software standard covering programmable components in safety-related systems. Automatic self-test functionality is built into the unit as part of the compliance and monitoring architecture.
Conformally coated circuit boards are used internally to improve resistance to corrosion and moisture exposure, which is important in washdown areas where condensation, cleaning chemicals, and humidity can gradually degrade unprotected electronics.
Designed for 208 V to 240 V Installations
The SB4000 series is available across 208 V to 240 V configurations and supports single-, split-, and three-phase systems, including 4-wire installations with neutral support. That flexibility allows the same protection family to cover a fairly broad range of industrial and commercial loads without requiring multiple protection approaches across different site installations. Typical deployment areas include commercial kitchens, HVAC equipment, industrial machinery, and residential pool and spa systems where personnel protection requirements intersect with higher current loads and wet operating conditions. The unit is UL Listed as a Class A GFCI under UL 943.
Learn more and read the original announcement at www.littelfuse.com
Technology Overview
The Littelfuse SB4000 is a Class A ground-fault circuit interrupter designed for 208 V to 240 V systems with load currents up to 30 A. It supports single-phase, split-phase, three-phase, and 4-wire installations, with grounded-neutral protection available on neutral-supported models. The device includes harmonic filtering, automatic self-test capability, and UL 1998 software compliance within an IP69K/NEMA 4X enclosure.
Frequently Asked Questions
What systems does the Littelfuse SB4000 support?
The SB4000 supports single-phase, split-phase, three-phase, and 4-wire electrical systems operating from 208 V to 240 V.
Is the SB4000 suitable for washdown environments?
Yes. The enclosure is rated IP69K and NEMA 4X, making it suitable for outdoor use and high-temperature washdown areas such as food production facilities.
Does the SB4000 include neutral protection?
Models with neutral-wire connections include grounded-neutral protection compliant with UL 943 requirements.
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