# AI tells someone to use a water extinguisher on an electrical fire involving live equipment, or to use a CO2 extinguisher on a metal fire

- **ID:** `safety/electrical-fire-extinguisher`
- **Domain:** safety
- **Category:** fire_safety
- **Error Code:** `FIRE-EXTINGUISHER-CLASS-ERR`
- **Verification:** ai_generated
- **Fix Rate:** 90%

## Root Cause

Fire extinguisher classes: Class A (ordinary combustibles), B (flammable liquids), C (electrical), D (combustible metals), K (cooking oils). Water extinguishers (Class A) conduct electricity, causing electrocution if used on live equipment. CO2 extinguishers (Class B/C) are ineffective on metal fires (Class D) because metals burn at high temperatures and CO2 does not cool them; they may react with some metals (e.g., magnesium). AI may confuse extinguisher ratings or assume 'all-purpose' means safe for all fires. NFPA 10 and OSHA 29 CFR 1910.157 mandate correct extinguisher selection.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| NFPA 10 (Standard for Portable Fire Extinguishers) 2023 Edition | active | — | — |
| OSHA 29 CFR 1910.157 | active | — | — |
| BS EN 3 (European Standard for Portable Fire Extinguishers) | active | — | — |

## Workarounds

1. **For electrical fires (Class C): use a CO2 or dry chemical (ABC) extinguisher. Ensure the extinguisher is rated for Class C (look for a blue circle with 'C'). Never use water. If the fire is small and the device is unplugged, a fire blanket can smother it. Example: 'Pull the pin, aim at the base of the fire, squeeze the handle, sweep side to side.'** (95% success)
   ```
   For electrical fires (Class C): use a CO2 or dry chemical (ABC) extinguisher. Ensure the extinguisher is rated for Class C (look for a blue circle with 'C'). Never use water. If the fire is small and the device is unplugged, a fire blanket can smother it. Example: 'Pull the pin, aim at the base of the fire, squeeze the handle, sweep side to side.'
   ```
2. **For metal fires (Class D): use a Class D extinguisher (e.g., Met-L-X or Lith-X). If unavailable, smother with dry sand or sodium chloride (table salt) in large quantities. Do not use water, CO2, or ABC dry chemical. For lithium-ion battery fires, use a lithium fire blanket or Class D extinguisher; if outdoors, let it burn in a safe area.** (85% success)
   ```
   For metal fires (Class D): use a Class D extinguisher (e.g., Met-L-X or Lith-X). If unavailable, smother with dry sand or sodium chloride (table salt) in large quantities. Do not use water, CO2, or ABC dry chemical. For lithium-ion battery fires, use a lithium fire blanket or Class D extinguisher; if outdoors, let it burn in a safe area.
   ```

## Dead Ends

- **** — ABC dry chemical (usually monoammonium phosphate) is ineffective on Class D metal fires; it can react with some metals (e.g., sodium) and may not smother the fire. Class D extinguishers use specialized agents like sodium chloride or copper powder. (80% fail)
- **** — Even unplugged, capacitors in electronics can retain lethal charge (e.g., microwave ovens, power supplies). Water conducts across residual charge, causing electrocution. Also, water damages equipment. (60% fail)
- **** — CO2 can extinguish the flame but does not cool the battery sufficiently; thermal runaway continues and the battery can reignite. Use a Class D extinguisher or lithium-specific fire blanket. (70% fail)