OEX ACX0034 Single Firewall & Bulkhead Stud - Black

OEX ACX0034 Black Single Firewall and Bulkhead Stud 250A 48V DC with Glass Filled Nylon Base

The OEX ACX0034 is the black coded negative and earth variant of the OEX single firewall bulkhead stud range, providing a clean, insulated and rated cable pass through point for routing high current negative or earth cables through metal firewalls, bulkheads, chassis rails, battery enclosure walls and custom electrical panels. It features two 3/8 16 thread brass stud terminals, a 250A continuous rating, 48V DC maximum operating voltage, an impact resistant plastic insulator and mounting bush, a glass filled nylon base, stainless steel nuts, 10mm brass bolts and a 32mm diameter mounting hole. Supplied individually with a one year warranty.

Product overview

Routing high current cables through a metal firewall or bulkhead without a proper insulated pass through creates risks of cable chafing, insulation damage and short circuits at the penetration point. The ACX0034 eliminates this by providing a fully insulated, panel mounted terminal stud that routes the negative or earth cable through the panel at a properly rated, isolated and identified connection point. The impact resistant plastic insulator and mounting bush provide full electrical isolation between the stud terminals and the surrounding metalwork, ensuring no continuity between the negative stud and the vehicle chassis or panel regardless of vibration or installation position.

Paired with the ACX0035 red positive bulkhead stud, the ACX0034 forms a complete colour coded positive and negative bulkhead stud pair, the professional solution for engine bay to cabin battery cable routing, battery box to accessory panel wiring, marine compartment bulkhead penetrations and any custom build where both positive and negative cables need to cross a metal barrier cleanly. The 250A continuous and 48V DC rating handles the demands of high current 12V and 24V electrical systems. The 32mm mounting hole suits standard hole saw sizes for straightforward installation. Manufactured under ISO 9001 quality management certification with in house testing at OEX's Brisbane facility.

Features and benefits

Clean insulated negative cable pass through for firewalls and bulkheads: Provides a fully insulated, panel mounted terminal point for routing high current negative and earth cables through metal firewalls and bulkheads, eliminating the risk of cable chafing, insulation damage and short circuits at metal panel penetration points.

Impact resistant plastic insulator and mounting bush: Provides full electrical isolation between the stud terminals and the surrounding metalwork, ensuring no continuity between the negative stud and the vehicle chassis or panel regardless of installation location or vibration.

Glass filled nylon base for superior strength and heat resistance: Glass filled nylon provides significantly greater rigidity, impact resistance and thermal stability than standard nylon, resisting deformation and cracking under sustained load and elevated temperatures in engine bays, battery compartments and industrial equipment enclosures.

250A continuous and 48V DC rating: Handles the high current demands of large inverter earth cables, amplifier main earth runs, dual battery negative cables and commercial vehicle auxiliary earth circuits in both 12V and 24V electrical systems.

Two 3/8 16 thread brass stud terminals: Dual stud terminals on both sides of the panel allow earth cables to be terminated cleanly on the engine bay side and the cabin side, creating a secure, rated connection point that passes negative current through the panel without bare cable penetration.

Stainless steel nuts and 10mm brass bolts: Corrosion resistant stainless and brass hardware provides vibration resistant clamping at both connection points, maintaining reliable electrical contact under thermal cycling and mechanical vibration in automotive and marine installations.

Black colour for negative and earth identification: Black colour coding provides instant identification as a negative or earth terminal, reducing polarity errors in installations where both positive and negative bulkhead studs are mounted side by side on the same panel.

32mm diameter mounting hole for standard tooling: The 32mm mounting hole suits standard hole saw sizes readily available at hardware stores, making installation straightforward without specialist tooling.

ISO 9001 certified manufacturing: Produced under ISO 9001 quality management certification with in house product testing at OEX's Brisbane facility.

Technical specs

Compatible with

The ACX0034 suits 12V and 24V automotive, marine, caravan, RV, 4WD, commercial vehicle and mining support vehicle applications requiring a clean, insulated 250A rated negative cable pass through point through metal firewalls, bulkheads, chassis rails, battery box walls and custom electrical panels. Pairs directly with the OEX ACX0035 red positive bulkhead stud for a complete colour coded positive and negative bulkhead stud pair. Compatible with standard cable lugs for 3/8 16 thread studs across a range of heavy gauge wire sizes.

Frequently asked questions

What is the difference between the ACX0034 and the ACX0035? The ACX0034 is the black coded negative and earth variant and the ACX0035 is the red coded positive variant. Both share identical specifications including 250A continuous rating, 48V DC maximum, dual 3/8 16 brass stud terminals, 15.9mm body length and 32mm mounting hole. The ACX0034 additionally features a glass filled nylon base. Use the ACX0035 for the positive cable pass through and the ACX0034 for the negative and earth cable pass through to form a complete, colour coded bulkhead stud pair.

How far apart should the ACX0034 and ACX0035 be mounted when installed as a pair? When installing both positive and negative bulkhead studs side by side, maintain sufficient separation to prevent accidental contact between the exposed stud terminals on either side of the panel. A minimum of 40 to 50mm centre to centre spacing is recommended as good practice, though the exact spacing depends on the cable lug sizes used and whether protective covers are fitted to the studs.

What size hole saw is needed to install the ACX0034? The ACX0034 requires a 32mm diameter mounting hole, which suits a standard 32mm hole saw available at most hardware stores. Drill the hole in the intended mounting location, deburr the edges thoroughly and test fit the mounting bush before final installation to ensure a clean, tight fit.

What cable lugs are compatible with the 3/8 16 thread studs? The 3/8 16 thread brass studs accept standard cable lugs with a 3/8 inch hole, available across a range of wire gauge sizes from light accessory wire through to heavy gauge cables suited to 250A rated automotive and marine applications. Always use correctly sized, properly crimped compression lugs matched to the wire gauge of each circuit.

Is the ACX0034 suitable for marine bulkhead installations? The brass stud construction, impact resistant plastic insulator and glass filled nylon base provide good corrosion resistance and electrical isolation suited to marine bulkhead applications. For best long term performance in marine environments, apply marine grade sealant around the mounting bush perimeter during installation to prevent water ingress through the panel hole, and use tinned copper cable lugs with dielectric grease on all contact surfaces.