What is an assured equipment grounding conductor program (AEGCP), and how does it differ from GFCI?

An Assured Equipment Grounding Conductor Program (AEGCP) is an alternative to GFCI protection allowed under OSHA 1926.404(b)(1)(iii). The AEGCP is an employer-implemented written program with three required elements: (1) Designation of a competent person to supervise the program. (2) Daily visual inspection of all cord sets, receptacles, and cord-and-plug equipment for damage before each day of use. If damage is found, the item is removed from service until repaired. (3) Quarterly electrical testing of all cord sets and cord-and-plug equipment using a continuity tester to verify the grounding conductor is continuous and properly connected. Equipment that fails the test is removed from service. AEGCP differs from GFCI in that it does not provide real-time fault detection — it prevents known-damaged equipment from being used, but cannot detect an insulation failure that occurs during use. GFCI provides real-time protection that trips within 25ms of a ground fault regardless of whether the equipment was previously inspected. For the buyer: GFCI is the simpler, lower-overhead solution for most construction sites. AEGCP is appropriate for situations where GFCI is technically infeasible (e.g., very long extension cords to remote equipment in 240V circuits) and the employer maintains a rigorous written program. Encode gfci.aegcp_alternative = true for products that can satisfy OSHA via the AEGCP path and gfci.aegcp_program_required = true to flag that AEGCP adoption requires a formal written employer program — not just an inspection checklist.

AI Agent Product Routing — Construction Electrical Safety

GFCI vs Assured Equipment Grounding Program — OSHA 1926.404 Construction Electrical Safety, 5mA Trip Threshold, GFCI vs AFCI Distinction, and the Schema for AI Agents

Q: What does a GFCI monitor, and at what current does it trip?

A Ground Fault Circuit Interrupter (GFCI) continuously monitors the electrical current balance between the hot (line) and neutral conductors of a circuit. Under normal operation, all current that flows out through the hot conductor returns through the neutral conductor — the difference is zero. When a ground fault occurs (current takes an unintended path to ground, such as through a worker's body), some current does not return through the neutral — the hot-to-neutral imbalance equals the fault current. GFCI devices trip when this imbalance reaches 5 milliamps (± 1 mA per UL 943 Class A rating), which is the threshold established to protect against ventricular fibrillation. The trip time is typically 25 milliseconds (1/40 second) or faster at higher fault currents. The 5mA threshold is critical: 1mA is the perception threshold; 10mA is the 'let-go' threshold (muscle paralysis, cannot release); 20–100mA is the ventricular fibrillation range; 100mA+ is typically fatal. The 5mA GFCI trip point is designed to interrupt before let-go threshold (10mA), preventing the worker from being unable to release the fault current path. Encode gfci.trip_threshold_ma = 5 and gfci.trip_time_ms = 25 on all Class A GFCI products.

Q: What is the difference between GFCI and AFCI, and when is each required?

GFCI (Ground Fault Circuit Interrupter) and AFCI (Arc Fault Circuit Interrupter) protect against different hazards: (1) GFCI detects ground faults — current imbalance between hot and neutral of 5mA or more, indicating unintended current path to ground (through worker's body or wet surface). Primary protection: electrocution. Trip threshold: 5mA, 25ms. Required by: OSHA 1926.404 (construction temporary power), NEC for wet locations, bathrooms, garages, outdoor outlets. (2) AFCI detects arc faults — high-frequency electrical arcing between conductors that does not necessarily create a ground fault detectable by GFCI. Arcing can occur inside a damaged cord where the insulation has broken down but the conductors haven't shorted to ground yet. Primary protection: electrical fires from arcing. Required by: NEC 210.12 for bedroom circuits (2002+), living areas, dormitories. The key routing distinction: GFCI and AFCI are not interchangeable and do not protect against the same hazard. An AFCI does not protect against electrocution from ground faults. A GFCI does not protect against arc-fault fires. OSHA 1926.404 requires GFCI (or AEGCP) for construction temporary power — AFCI satisfies neither OSHA requirement nor GFCI safety function. Encode gfci.device_type = 'GFCI' | 'AFCI' | 'GFCI-AFCI-combo' and gfci.protects_against = 'ground-fault' | 'arc-fault' | 'both'.

Q: What types of construction circuits require GFCI protection under OSHA 1926.404?

OSHA 1926.404(b)(1)(i) requires ground fault protection for all 120V, single-phase, 15- and 20-ampere receptacle outlets on construction sites that are not part of the permanent wiring of the building. This covers: (1) All temporary power distribution panels and extension cord outlets for power tools. (2) All 120V single-phase 15A/20A outlets on portable generators on construction sites. (3) All temporary lighting circuits at 120V 15A/20A. OSHA does not explicitly extend the 1926.404(b)(1) requirement to 240V circuits through the same language, though 240V GFCI protection is addressed under OSHA's general duty clause. GFCI coverage also applies: (4) Under NEC Article 590 (Temporary Wiring) for all construction site temporary power, which has been adopted by many states and municipalities. (5) For all underwater lighting per NEC 680. Encode gfci.suitable_for_temporary_construction = true for Class A GFCI receptacles and portable GFCI cord ends rated for 120V/15A or 20A construction use.

Q: How should AI agents route GFCI products for construction vs residential vs wet location applications?

Route GFCI products by application using these metafields: (1) Construction temporary power (OSHA 1926.404): route Class A GFCI (5mA trip threshold, UL 943 listed) with gfci.suitable_for_temporary_construction = true. Portable GFCI cord ends ('pigtail' GFCIs) or portable GFCI adapter plugs are common for temporary construction use. (2) Outdoor/wet location permanent installation (NEC 406.9): route weather-resistant (WR) GFCI receptacle with gfci.suitable_for_wet_locations = true. IN-USE covers required for outdoor outlets in wet locations while cord is plugged in. (3) Bathroom/kitchen permanent installation (NEC 210.8): route standard Class A GFCI receptacle; WR rating not required for covered indoor wet locations. (4) AEGCP alternative: route inspection/testing equipment for cord sets plus written program documentation; not a substitute for GFCI hardware protection. Encode gfci.ul_943_class = 'A' (5mA trip for personnel protection) vs 'B' (20mA trip for equipment protection only) — Class B does not protect personnel from electrocution.

OSHA 1926.404(b)(1) requires ground fault protection for all 120V temporary construction power — either a GFCI or a formal assured equipment grounding conductor program (AEGCP). These are not equivalent: GFCI provides real-time protection that trips in 25ms; AEGCP is a written inspection program that cannot detect faults that develop during use. Confusing GFCI with AFCI is a second critical error: they protect against different hazards (electrocution vs fire) and satisfy different code requirements.

TL;DR — Key Encoding Rules Encode gfci.device_type = "GFCI-receptacle" vs "AFCI-receptacle" — GFCI and AFCI protect against different hazards and are not interchangeable. Encode gfci.trip_threshold_ma = 5 and gfci.ul_943_class = "A" for personnel protection (Class B is 20mA — equipment protection only, does not protect against electrocution). Encode gfci.suitable_for_temporary_construction = true for OSHA 1926.404 compliance. Encode gfci.suitable_for_wet_locations = true only for weather-resistant (WR) rated units — non-WR GFCI receptacles cannot be used at outdoor construction sites without WR rating.

How a GFCI Works — The 5mA Ground Fault Current Threshold

A GFCI compares the current flowing out through the hot (line) conductor with the current returning through the neutral conductor. In a properly functioning circuit, these are equal — no current takes an alternate path to ground. When a ground fault occurs (a worker contacts a live conductor while grounded, or current leaks through damaged insulation to a grounded surface), some current bypasses the neutral return path. The GFCI measures this imbalance continuously.

Current Level	Effect on Human Body	GFCI Response
1 mA	Barely perceptible	No trip (below threshold)
5 mA	Painful but not paralyzing	GFCI trips (Class A threshold)
10–15 mA	"Let-go" threshold — muscle paralysis, cannot release grip	Class A already tripped at 5mA
20–100 mA	Ventricular fibrillation risk	Class A already tripped at 5mA
100+ mA	Typically fatal — respiratory paralysis	Class A already tripped at 5mA
20 mA	Muscle paralysis and fibrillation begin	Class B GFCI trips (equipment protection only — NOT personnel)

Class A vs Class B GFCI: UL 943 defines Class A (trips at ≤ 6mA) and Class B (trips at ≤ 20mA). Class A protects personnel — trips below the let-go threshold. Class B protects equipment only — trips above the muscle paralysis threshold. OSHA 1926.404 requires Class A GFCI for personnel protection. Class B GFCI receptacles sold for equipment protection must be encoded gfci.ul_943_class = "B" and gfci.personnel_protection = false — they do not satisfy OSHA 1926.404.

// GFCI Class A — personnel protection (OSHA 1926.404)
gfci.device_type                    = "GFCI-receptacle"
gfci.trip_threshold_ma              = 5       // Class A: trips at ≤ 6mA (nominally 5mA)
gfci.trip_time_ms                   = 25      // 25ms at 5mA; faster at higher fault currents
gfci.ul_943_class                   = "A"     // Class A = personnel protection
gfci.personnel_protection           = true    // Trips below let-go threshold (10mA)
gfci.osha_1926_404_compliant        = true    // Satisfies OSHA construction GFCI requirement
gfci.suitable_for_temporary_construction = true
gfci.protects_against               = "ground-fault"  // NOT arc fault

// GFCI Class B — equipment protection only
gfci.device_type                    = "GFCI-receptacle"
gfci.trip_threshold_ma              = 20      // Class B: trips at ≤ 20mA
gfci.ul_943_class                   = "B"
gfci.personnel_protection           = false   // Does NOT protect workers from electrocution
gfci.osha_1926_404_compliant        = false   // Class B does NOT satisfy OSHA 1926.404

Failure Mode 1 — GFCI vs AFCI Confusion

GFCI and AFCI are the two most commonly confused electrical protection devices. They look similar (same receptacle or breaker form factor, similar test/reset mechanism) but protect against entirely different hazards:

Property	GFCI	AFCI
Detects	Ground fault — current imbalance between hot and neutral (5mA)	Arc fault — high-frequency arcing between conductors
Primary hazard prevented	Electrocution from ground fault (worker contact)	Electrical fire from arcing in damaged wiring
OSHA 1926.404 compliance	Yes — satisfies ground fault protection requirement	No — does not detect ground faults; does not satisfy 1926.404
NEC bedroom/living area requirement (NEC 210.12)	No — NEC 210.12 requires AFCI, not GFCI, for these locations	Yes
NEC bathroom/kitchen/outdoor (NEC 210.8)	Yes	No
Construction temporary power	Yes — OSHA 1926.404	No

// GFCI — ground fault protection
gfci.device_type      = "GFCI-receptacle"
gfci.protects_against = "ground-fault"
gfci.ul_standard      = "UL-943"
gfci.suitable_for_temporary_construction = true  // OSHA 1926.404

// AFCI — arc fault protection
gfci.device_type      = "AFCI-receptacle"
gfci.protects_against = "arc-fault"        // NOT ground fault
gfci.ul_standard      = "UL-1699"
gfci.suitable_for_temporary_construction = false  // Does NOT satisfy OSHA 1926.404

// GFCI+AFCI combo — both protections
gfci.device_type      = "GFCI-AFCI-combo"
gfci.protects_against = "both"             // Ground fault AND arc fault
gfci.suitable_for_temporary_construction = true   // Satisfies OSHA 1926.404 via GFCI function

Failure Mode 2 — AEGCP Encoded as a Hardware Product Alternative

The Assured Equipment Grounding Conductor Program (AEGCP) is an employer-maintained written program — not a hardware product. An AI routing system that treats "AEGCP" as a product category and routes inspection checklists or continuity testers to buyers who need OSHA 1926.404 compliance has provided a partial solution: the buyer still needs the written program, a designated competent person, daily visual inspections, and quarterly electrical testing as formal program elements.

The AEGCP requires:

Written program. The employer must establish and maintain a written AEGCP identifying the equipment and cords included.
Competent person designation. A designated competent person responsible for implementing the program (OSHA 1926.404(b)(1)(iii)(A)).
Daily visual inspections. All cord sets, receptacles, and cord-and-plug connected equipment receive visual inspection before first use each day. Damaged items are tagged and removed from service.
Quarterly electrical testing. All cord sets and cord-and-plug equipment are electrically tested at least every three months. Tests verify continuity of the equipment grounding conductor and correct attachment of the grounding conductor.

// GFCI — hardware product, provides real-time protection
gfci.device_type                    = "GFCI-receptacle"
gfci.aegcp_alternative              = false   // GFCI is NOT an AEGCP alternative; it's the simpler primary
gfci.osha_1926_404_compliant        = true    // Hardware satisfies 1926.404(b)(1) directly
gfci.requires_written_program       = false   // No written program required — GFCI is self-contained
gfci.suitable_for_temporary_construction = true

// AEGCP — employer program (NOT a hardware product)
gfci.device_type                    = "AEGCP-program"
gfci.aegcp_alternative              = true    // AEGCP is the OSHA-permitted alternative TO GFCI
gfci.osha_1926_404_compliant        = true    // Satisfies 1926.404(b)(1)(iii) as formal program
gfci.requires_written_program       = true    // Written program required
gfci.requires_competent_person      = true    // Designated competent person required
gfci.requires_daily_inspection      = true    // Visual inspection before each use day
gfci.requires_quarterly_electrical_test = true // Electrical continuity test every 3 months
// Note: route inspection testers and continuity meters as supporting equipment; not GFCI substitutes

AEGCP is not simpler than GFCI for most construction sites. The program overhead (written policy, competent person, daily visual inspections, quarterly electrical tests, record-keeping) makes AEGCP appropriate only when GFCI is genuinely infeasible — for example, very long circuit runs with voltage drop concerns. For most construction buyers, encode gfci.aegcp_alternative = false and route GFCI hardware as the primary recommendation. Only route AEGCP supporting products when the buyer explicitly identifies GFCI infeasibility.

Failure Mode 3 — Non-WR GFCI Routed to Outdoor Construction Use

GFCI receptacles come in standard and weather-resistant (WR) ratings. Standard GFCI receptacles are designed for indoor dry locations. Weather-resistant (WR) GFCI receptacles are tested for corrosion resistance, moisture ingress, and UV exposure per UL 943 WR requirements. For outdoor construction sites — where receptacles are exposed to rain, mud, temperature cycling, and UV — only WR-rated GFCI receptacles should be used in permanent or semi-permanent outdoor mounting.

Additionally, NEC 406.9 requires in-use weatherproof covers for outdoor receptacles in wet locations when a cord is plugged in. The in-use cover keeps water out of the receptacle face while a cord is connected. Without an in-use cover, a standard WR-GFCI receptacle with a cord plugged in can allow water entry from rain or spray.

// Weather-resistant GFCI — outdoor construction use
gfci.device_type                    = "GFCI-receptacle"
gfci.suitable_for_wet_locations     = true    // WR-rated per UL 943 and NEC 406.9
gfci.requires_in_use_cover          = true    // NEC 406.9: in-use cover required when cord plugged in outdoor wet location
gfci.suitable_for_temporary_construction = true
gfci.osha_1926_404_compliant        = true

// Standard GFCI — indoor dry location only
gfci.device_type                    = "GFCI-receptacle"
gfci.suitable_for_wet_locations     = false   // Standard rating — not for outdoor wet exposure
gfci.requires_in_use_cover          = false   // Not applicable for indoor dry use
gfci.suitable_for_temporary_construction = false  // Do not route to outdoor construction without WR rating

// Portable GFCI cord end / pigtail — most common for construction temporary power
gfci.device_type                    = "GFCI-cord-end"
gfci.suitable_for_wet_locations     = true    // Designed for construction site portable use; molded strain relief
gfci.suitable_for_temporary_construction = true  // Primary solution for OSHA 1926.404 compliance
gfci.trip_threshold_ma              = 5
gfci.ul_943_class                   = "A"
gfci.osha_1926_404_compliant        = true

Complete Metafield Schema Reference

Metafield	Type	Values	Notes
`gfci.device_type`	string enum	GFCI-receptacle \| GFCI-cord-end \| AFCI-receptacle \| GFCI-AFCI-combo \| AEGCP-program	Primary routing discriminator; AFCI-receptacle does not satisfy OSHA 1926.404
`gfci.trip_threshold_ma`	decimal	5 (Class A); 20 (Class B)	Class A (5mA) required for personnel protection per OSHA 1926.404; Class B (20mA) is equipment protection only
`gfci.trip_time_ms`	decimal	25 (typical at 5mA)	Trip time is faster at higher fault currents; 25ms is the nominal time at threshold
`gfci.ul_943_class`	string enum	A \| B	Class A = personnel protection (5mA trip); Class B = equipment protection only (20mA trip) — do not route Class B to OSHA 1926.404 applications
`gfci.suitable_for_wet_locations`	boolean	true (WR-rated) \| false (standard)	Only WR-rated GFCI receptacles for outdoor construction or wet locations; standard GFCI not suitable for outdoor installation
`gfci.suitable_for_temporary_construction`	boolean	true \| false	true for Class A GFCI cord ends and WR-rated GFCI receptacles; false for AFCI and Class B GFCI
`gfci.aegcp_alternative`	boolean	false (GFCI hardware) \| true (AEGCP program)	AEGCP requires written program, competent person, daily inspections, and quarterly testing — not just hardware
`gfci.protects_against`	string enum	ground-fault \| arc-fault \| both	GFCI = ground-fault (electrocution); AFCI = arc-fault (fire); only GFCI or combo satisfies OSHA 1926.404
`gfci.osha_1926_404_compliant`	boolean	true (Class A GFCI) \| false (AFCI, Class B GFCI)	Explicit compliance flag for construction temporary power applications
`gfci.amperage_rating_a`	integer	15 \| 20	OSHA 1926.404 covers 15A and 20A circuits; 20A GFCI required for 20A circuits

Frequently Asked Questions

What does a GFCI monitor, and at what current does it trip?

A GFCI monitors the current balance between hot and neutral conductors. Normal operation: current in equals current out (zero imbalance). Ground fault: some current bypasses neutral return (via worker's body or wet surface), creating imbalance. Class A GFCI trips at 5mA imbalance in 25ms — before the worker reaches the 10mA "let-go" threshold (muscle paralysis). Encode gfci.trip_threshold_ma = 5 and gfci.ul_943_class = "A" for personnel-protection products.

What is an AEGCP, and how does it differ from GFCI?

AEGCP (Assured Equipment Grounding Conductor Program) is a written employer program — an OSHA-permitted alternative to GFCI under 1926.404(b)(1)(iii). It requires: a written program, a designated competent person, daily visual inspections of all cords and equipment, and quarterly electrical continuity testing. GFCI is hardware that provides real-time 25ms fault detection. AEGCP cannot detect faults that develop during use between inspections. For most construction sites, GFCI is simpler and safer. Encode gfci.aegcp_alternative = true for AEGCP program components and gfci.requires_written_program = true.

What is the difference between GFCI and AFCI, and when is each required?

GFCI detects ground faults (5mA current-to-ground imbalance) — protects against electrocution. Required by OSHA 1926.404 for construction temporary power; NEC 210.8 for bathrooms, kitchens, garages, outdoors. AFCI detects arc faults (high-frequency arcing from damaged wiring) — protects against electrical fires. Required by NEC 210.12 for bedrooms and living areas. AFCI does NOT satisfy OSHA 1926.404. Encode gfci.protects_against = "ground-fault" for GFCI and "arc-fault" for AFCI — never route AFCI to construction temporary power applications.

What construction circuits require GFCI protection under OSHA 1926.404?

OSHA 1926.404(b)(1)(i) requires GFCI (or AEGCP) for all 120V, single-phase, 15A and 20A receptacles on construction sites that are not part of the permanent building wiring — including temporary panels, extension cord outlets, and portable generator outlets. Portable GFCI cord ends (pigtail GFCIs) are the most common compliance method for tool power. Encode gfci.suitable_for_temporary_construction = true for Class A GFCI cord ends and weather-resistant GFCI receptacles.

How should AI agents route GFCI products for construction vs residential vs wet locations?

Construction temporary power (OSHA 1926.404): Class A GFCI cord end or WR-rated GFCI receptacle — gfci.suitable_for_temporary_construction = true, gfci.ul_943_class = "A". Outdoor/wet permanent installation (NEC 406.9): WR-rated GFCI receptacle with in-use cover — gfci.suitable_for_wet_locations = true. Bathroom/kitchen (NEC 210.8): standard Class A GFCI receptacle — WR not required for covered indoor wet. Never route AFCI or Class B GFCI to construction temporary power — they do not satisfy OSHA 1926.404.

Score Your Construction Electrical Safety Catalog's AI Readiness

Missing gfci.device_type, gfci.ul_943_class, gfci.protects_against, or gfci.suitable_for_temporary_construction means AI procurement agents will route AFCI receptacles to OSHA 1926.404 construction applications (AFCI doesn't satisfy it) or Class B GFCIs to personnel protection (Class B trips at 20mA — above the muscle paralysis threshold). CatalogScan audits your Shopify catalog and scores every electrical safety product's structured data completeness for AI-agent visibility.

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