- USPS 955 has exactly two parts: Multicraft (60 items, 60 minutes) and Spatial Relations (68 items, 40 minutes).
- Content spans 9 domains drawn from 21 technical fields and roughly 131 topics - not a single trade test.
- USPS reports domain performance only as High, Average, or Low; no percentage weighting is published anywhere.
- A 70 excluding Veterans' Preference is the minimum score to be considered, with eligible ratings from 70 to 100.
Exam Structure Overview: Two Parts, Nine Domains
USPS Maintenance Exam 955 is defined by the official USPS Assessment Information Package as having exactly two parts, not nine separate tests. The nine "domains" referenced throughout this guide are the content areas that USPS pulls questions from within those two parts - they are a study organization tool, not an official exam section breakdown. Understanding this distinction matters because it explains why your Notice of Results shows performance bands rather than nine individual scores.
The exam is administered directly by USPS under Handbook EL-304, the Maintenance Selection System, and delivered at approved test centers as a proctored, computer-based assessment. Bring valid photo identification. USPS charges no fee for the exam, the application, or any employment information - if anyone asks you to pay to take Exam 955, that is a scam the Postal Inspection Service actively investigates. For a full walkthrough of eligibility mechanics before you even reach the domains, see our USPS 955 Requirements guide.
The Multicraft Domains (1-7)
The Multicraft portion draws from seven content domains that blend hands-on craft knowledge with the underlying science behind it. USPS does not publish a percentage weighting for any of these areas, so candidates should treat every domain as fair game rather than trying to guess which topic carries more points.
Domain 1: AC/DC Theory, Power Distribution, and Electrical Maintenance
Covers fundamental circuit theory, how power is distributed through a facility, and the practical maintenance tasks electricians and mechanics perform on live and de-energized systems.
- Ohm's Law, series/parallel circuits, and basic troubleshooting logic
- Transformers, distribution panels, and safe lockout/tagout procedures
- Common electrical maintenance faults and corrective actions
Domain 2: Motors, Control Circuits, Schematics, and Print Reading
Focuses on how motors start, run, and are protected, plus the ability to trace a fault through a wiring diagram or control schematic.
- Motor types, starters, and overload protection
- Relay logic and ladder-diagram interpretation
- Reading blueprints and mechanical/electrical prints accurately
Domain 3: Digital Electronics, Power Supplies, Computers, and Test Instruments
Tests familiarity with digital logic basics, power supply function, and the meters and instruments used to diagnose electronic faults.
- Basic digital logic gates and binary concepts
- DC power supply components and failure symptoms
- Multimeter, oscilloscope, and test-instrument usage
Domain 4: Hydraulics and Pneumatics
Assesses understanding of fluid power systems used throughout mail-processing equipment, including how pressure, flow, and actuators interact.
- Hydraulic cylinders, valves, and pressure relief components
- Pneumatic control circuits and compressed-air systems
- Common failure modes in fluid power components
Domain 5: Pumps, Piping and Combustion
Covers pump types and applications, piping systems, and the basics of combustion equipment found in facility mechanical rooms.
- Centrifugal vs. positive displacement pumps
- Piping materials, fittings, and system layout logic
- Combustion process fundamentals and boiler-adjacent equipment
Domain 6: Power Transmission, Lubrication, Mechanical Maintenance, and Shop Machines, Tools and Equipment
This is the broadest Multicraft domain, spanning belts, chains, gears, lubrication practices, and the general shop tools a mechanic uses daily.
- Belt/pulley and chain/sprocket drive systems
- Lubrication types, intervals, and purposes
- Hand tools, power tools, and machine shop equipment identification
Domain 7: Welding and Rigging
Tests knowledge of welding processes and safe rigging practices for moving and securing heavy equipment.
- Common welding processes and their applications
- Rigging hardware, load calculations, and safety practices
- Metal properties relevant to fabrication and repair
Key Takeaway
All seven Multicraft domains compete for the same 60 items in 60 minutes - roughly one minute per question - so recognizing a topic quickly matters as much as knowing the answer.
The Spatial Relations Domains (8-9)
The second part of Exam 955 is entirely non-verbal and mechanical-reasoning based. It carries more items (68) than Multicraft but runs in less time (40 minutes), which makes pacing here just as critical as technical recall in the first part.
Domain 8: Spatial Relations - Matching Parts and Figures
Presents loose, disassembled pieces and asks the candidate to determine which assembled figure they would form without gaps or overlap.
- Mentally rotating and repositioning irregular shapes
- Ruling out near-miss answer choices with subtle gaps
- Working quickly since items are answered in rapid succession
Domain 9: Spatial Relations - Spatial Visualization
Shows a solid object's top, front, and right views and requires the candidate to identify which 3D solid would produce that exact set of views.
- Translating 2D orthographic views into a 3D mental model
- Eliminating solids that match two views but fail the third
- Building speed through repeated practice with view-based reasoning
How USPS Reports Domain Performance
USPS does not hand back a percentage score per domain. Instead, content-area performance is reported only in High, Average, and Low bands, and no percentage weighting per knowledge area is ever published. Your overall eligibility comes from a single combined rating between 70 and 100, with 70 as the minimum needed for consideration on any position you applied for - excluding Veterans' Preference points, which are added only after you've already passed and can never turn a failing score into an eligible one.
Because the bands are qualitative, chasing an exact "target score" per domain isn't realistic. What is realistic is making sure no domain lands in the Low band, since a single weak area among the 21 underlying technical fields and roughly 131 topics can drag down your overall rating even if you're strong everywhere else. For the exact numeric mechanics behind eligibility, read our passing score breakdown.
| Part | Items | Time | Domains Covered |
|---|---|---|---|
| Multicraft | 60 | 60 minutes | Domains 1-7 |
| Spatial Relations | 68 | 40 minutes | Domains 8-9 |
Who Actually Uses These Domains: Job Titles Behind the Exam
These nine domains aren't abstract - each maps to real maintenance craft positions filled through the Maintenance Selection System. Knowing which job you're targeting can help you decide where to spend extra review time.
- Electronic Technician (PS-10/PS-11): leans heavily on Domains 1-3
- Maintenance Mechanic MPE, Area Maintenance Specialist, Building Equipment Mechanic: draws broadly across Domains 4-6
- Maintenance Electrician: concentrated in Domains 1-2
- Machinist, Carpenter, Mason, Plumber, Painter, Blacksmith-Welder, Letter Box Mechanic: rely on Domains 5-7
- Building Maintenance Custodian: general mechanical familiarity across multiple domains
There are no formal education prerequisites to sit for Exam 955, and it's open both to external entrance applicants and to current employees during the Maintenance Craft in-service open season. If you're weighing whether any of these roles are worth pursuing, our salary guide and ROI analysis cover that side of the decision, and USPS 955 Jobs breaks down the position list further.
Key Takeaway
If you're an in-service employee testing for a score update, you can reschedule 120 days after your original exam date - the same 120-day window entrance applicants use to retake or reuse an existing score.
Building a Domain-by-Domain Study Plan
Rather than studying generically, map your prep calendar directly onto the nine domains so you spend time where your background is weakest. Someone coming from an electrical trade should push harder on Domains 4-7; someone from a mechanical trade should push harder on Domains 1-3 and both Spatial Relations domains.
Electrical Foundations
- Review Domain 1 (AC/DC theory, power distribution)
- Practice Domain 2 schematic and print-reading items
Electronics and Instrumentation
- Work through Domain 3 digital electronics and test-instrument questions
- Start light daily reps on Domain 8 matching-parts items
Fluid Power and Mechanical Systems
- Cover Domains 4 and 5 (hydraulics, pneumatics, pumps, piping, combustion)
- Continue Domain 9 spatial visualization drills
Mechanical Maintenance and Full Simulation
- Finish Domain 6 shop machines/tools and Domain 7 welding/rigging
- Run full-length, timed practice combining all 9 domains
This kind of scheduling only works if you're also tracking accuracy by domain rather than just an overall score, so you can see which content areas would land you in the Low band. Our full USPS 955 Study Guide expands this into a complete first-attempt strategy, and you can run timed, domain-tagged practice sessions on the main practice test platform to simulate the real 60-minute and 40-minute time limits separately.
Frequently Asked Questions
No. The official USPS Assessment Information Package defines exactly two parts - Multicraft and Spatial Relations. The nine domains are a content-organization structure used to group the 21 technical fields and roughly 131 topics that feed into those two parts for study purposes.
USPS reports content-area performance only in High, Average, and Low bands, with no percentage weighting published per knowledge area. You won't get a granular numeric breakdown by domain, only your overall combined rating.
The exam draws from 21 technical fields across the 9 domains, but no percentage weighting is published, so no single field is guaranteed to dominate the test. Broad coverage across all domains is safer than deep focus on just one or two.
No. That component belonged to the retired Exam 473 and does not exist on Exam 955, even though some outdated study guides still mention it. Exam 955 consists solely of the Multicraft and Spatial Relations parts covering the 9 domains above.
Electronic Technician (PS-10/PS-11) roles draw heavily on Domains 1 through 3 - AC/DC theory and power distribution, motors and schematics, and digital electronics with test instruments - though both Spatial Relations domains still count toward your overall eligibility.