Littelfuse: SB4000 Expands Shock Block Ground-Fault Circuit Interrupter (GFCI) Series
May 19, 2026
Littelfuse, Inc. expands its Industrial Shock Block Series to help protect workers from electrical shock for loads up to 30A. The SB4000 is available for use in single-, split- and three-phase systems as well as 4-wire systems from 208 to 240V.
SB4000 models equipped with connections for a neutral wire have built-in grounded-neutral protection per the UL 943 standard. The standard enclosure is IP 69K/NEMA 4X and outdoor rated making it suitable for all industrial environments including high temperature washdown used in food production applications. The SB4000 is panel agnostic making it perfect for remodel and retrofit applications in commercial kitchens, HVAC, and residential pool & spa applications. It includes advanced harmonic filtering, an automatic self-test feature, and is compliant to the UL 1998 Software in Programmable Components standard.
“In industrial and OEM environments, where 30-amp circuits power critical equipment, GFCI protection isn’t optional–it’s essential, especially where moisture and heavy-duty equipment intersect,” stated Tim Piemonte, Product Manager at Littelfuse. “The compact, cost-effective Shock Block SB4000 is a frontline defense against electrical hazards instantly disconnecting power in the event of a ground fault, and is a proactive step toward compliance, reliability and most importantly worker safety.”
Other feature and benefits include:
- UL 943 inverse time detection circuit protects people and the probability of nuisance tripping
- Fixed 6 mA trip level meets UL 943 GFCI personnel protection requirements
- Streamlined design eliminates flying leads and offers flexible positioning for knockouts
- Conformally coated circuit boards protect against corrosion and moisture
- Quick installation and easy configuration save time and money
The UL Listed SB4000 Shock Block series is a Class A GFCI available in 208 – 240V allowing maintenance or retrofit projects to meet the National Electrical Code NEC 210.8 for a wide variety of single-, split-, three-phase and 4-wire (neutral supported) systems.
