Class C Fire Extinguishers for Electrical Fires

CO2 and Halotron clean agents put out a fire in energized electrical equipment and leave nothing behind. They are non-conductive and residue-free, so there is no powder to clean off the boards and no corrosion afterward. That no-residue protection is why they are chosen for server rooms, switchgear, avionics, and other high-value electronics, and why dry chemical is the one to keep away from the gear: it carries the same Class C rating for shock safety, but its corrosive powder can ruin the equipment you were trying to save.

Last updated: July 21, 2026

The short version

A Class C rating means the agent is non-conductive and safe on energized electrical equipment. It carries no number.
Dry chemical is Class C rated, but its residue can corrode electronics and force a teardown.
CO2 and Halotron clean agent are both residue-free and non-conductive. Neither leaves powder behind.
The larger Halotron handhelds also carry a Class A rating; CO2 does not.

Who this guide is for

Facility and IT managers protecting server rooms, electrical rooms, and equipment areas.
Contractors and site teams guarding installed switchgear and energized gear.
Anyone deciding between dry chemical, CO2, and clean agent for live electronics.
Buyers replacing an old Halon unit near electronics.

The residue-free lineup at a glance

Every unit below is non-conductive and leaves no residue, so any of them protects energized gear the way dry chemical cannot. Halotron adds Class A coverage as it grows; CO2 stays Class B and C. Discharge time and reach are the practical differences between the sizes.

Unit	UL rating	Class A	Discharge	Reach	Typical use	Price
2.5 lb Halotron	2-B:C	No	9 s	6–10 ft	Aircraft, equipment cabs, network closets	$272.00
5 lb Halotron	5-B:C	No	9 s	9–15 ft	Boat helm, cockpit, equipment rooms	$518.00
11 lb Halotron	1-A:10-B:C	Yes	9 s	9–15 ft	Jobsite switchgear, data centers	$1,105.00
15.5 lb Halotron	2-A:10-B:C	Yes	13 s	12–18 ft	Server rooms, hangars, switchgear rooms	$1,500.00
10 lb CO2	10-B:C	No	9 s	4–8 ft	Telecom shelters, electrical rooms	$264.00
15 lb CO2	10-B:C	No	15 s	4–8 ft	Larger electrical rooms, plant gear	$307.00
20 lb CO2	10-B:C	No	20 s	4–8 ft	Equipment-dense rooms, plant electrical	$367.00

The 10, 15, and 20 lb CO2 all carry the same 10-B:C rating; the extra agent buys discharge time, not reach. For larger hazards, wheeled units go further: 65 lb Halotron (4-A:60-B:C, 20 s, 15–25 ft), 150 lb Halotron (10-A:120-B:C, 30 s), and 50 lb CO2 (20-B:C, 40 s, 15 ft).

Shop Halotron →Shop CO2 →Shop wheeled →

What a Class C rating means

Unlike the Class A and Class B numbers on a label, Class C has no number in front of it. The C means one thing: the extinguishing agent is non-conductive, so it is safe to use on energized electrical equipment without the discharge carrying current back to the operator. It is a safety rating for the person holding the extinguisher, not a measure of how much fire the unit can put out.

A Class C fire is really an energized-electrical situation rather than a distinct fuel. The fuel underneath is usually ordinary combustibles (Class A) like cable insulation and plastics, or a flammable liquid (Class B). Cut the power and, in practice, you are left fighting that underlying Class A or Class B fire. That is why a good Class C unit is chosen for both its non-conductive agent and its A or B rating. NFPA 10 governs how the unit is selected and placed, and UL 711 defines the A and B ratings through live-fire tests and the C rating through a test of the agent's electrical non-conductivity.

The distinction that matters: Class C rated means safe on energized gear. It does not mean gentle on the gear. Several agents carry a C rating, and they behave very differently once the fire is out.

Why dry chemical damages live equipment

A multipurpose ABC dry chemical extinguisher does carry a Class C rating. The agent is non-conductive, so it will not shock the operator, and it will knock down a fire in energized gear. That is exactly why it is the unit most people reach for. The problem is what it leaves behind.

ABC dry chemical is monoammonium-phosphate based, a fine powder. On discharge it coats every surface it reaches and works into connectors, card cages, and cooling paths. The powder is mildly acidic and hygroscopic, meaning it draws moisture from the air, and on energized circuit boards that combination can corrode copper traces and contacts over the days and weeks after the discharge. Equipment that came through the fire itself can still fail later from the residue alone, and cleaning the powder out of a populated rack is usually a teardown job rather than a wipe-down.

One of our own customers, a general contractor protecting installed switchgear on a jobsite, put the case for a clean agent plainly: "We have electrical gear and if there was a fire and we used an ABC extinguisher, we would have to dismantle and clean all the gear." That is the whole reason to keep dry chemical away from equipment you want to keep.

Warning: Class C rated is not the same as equipment safe. A dry chemical unit is rated for energized electrical fires and will not electrocute the operator, but its residue can ruin the boards, drives, and controls you were trying to save. For live equipment worth more than the extinguisher, choose a residue-free agent.

Clean agent vs CO2, the two residue-free options

That leaves two agents that put out an electrical fire and leave nothing behind: Halotron clean agent and carbon dioxide. Both are non-conductive and both are residue-free, so either one protects the equipment the way dry chemical cannot. The differences decide which one belongs where.

Factor	Halotron clean agent	CO2
Residue	None, evaporating liquid	None, discharges as a gas
Conductivity	Non-conductive, safe on energized gear	Non-conductive, safe on energized gear
Fire classes	Class B and C, with Class A on the 11 and 15.5 lb sizes	Class B and C (no Class A rating)
Reach and wind	Discharge stream carries better in the open	Shorter reach, weaker outdoors or in a draft
Small enclosed rooms	Lower oxygen concern than CO2; ventilate after use	Displaces oxygen, ventilate before re-entry
Where it fits	Small occupied rooms and mixed hazards that need Class A too	Cost-effective for electrical rooms and equipment areas

Ratings vary by unit size. Compare the UL rating on the specific extinguisher, not just the agent name.

Clean agent (Halotron) extinguishers

Halotron I is a halocarbon clean agent based on HCFC-123, developed as the modern portable replacement for Halon 1211. It discharges as a rapidly evaporating liquid that leaves no residue and does not conduct electricity, so it protects energized gear the same way CO2 does. Unlike CO2, Halotron does not put the fire out by displacing oxygen, so at handheld sizes it is a lower asphyxiation risk in a small, occupied room, though you still ventilate after any discharge.

The bigger difference is Class A coverage. The larger Halotron handhelds add an A rating, so an 11 lb unit (1-A:10-B:C) or a 15.5 lb unit (2-A:10-B:C) covers ordinary combustibles as well as energized equipment, while the 2.5 lb (2-B:C) and 5 lb (5-B:C) units stay Class B and C only. Halotron extinguishers are listed to UL 2129 and rated under UL 711. Fixed room-flooding clean-agent systems are a separate topic, covered by NFPA 2001, and the fire protection of IT equipment rooms is covered by NFPA 75.

Buckeye Fire Equipment builds its Halotron line in Kings Mountain, North Carolina, from a 2.5 lb handheld up to 65 and 150 lb wheeled units. If you are replacing an old Halon unit, the Halon replacement guide walks the swap and how to retire the old cylinder.

CO2 extinguishers

A CO2 extinguisher discharges compressed carbon dioxide, smothers the fire, and leaves nothing behind to clean up or corrode. It is non-conductive and rated Class B and C, which makes it a common, cost-effective choice for electrical rooms, labs, and equipment areas. It has no Class A rating, so it will not hold a fire in ordinary combustibles like cardboard or wood on its own.

Two limits are worth knowing. CO2 works by displacing oxygen, so in a small closed room ventilate before you re-enter. And its reach is short and fades outdoors or in a draft. CO2 units are built and listed to UL 154, and because they are pressurized cylinders with no gauge, they run on a distinct service cycle covered in our CO2 inspection and testing guide.

Where each one fits

The right agent depends on the space and what else is in it. These are the common electrical-hazard scenarios, each with the guide that covers it in depth.

Server rooms & sensitive electronics

Racks, drives, and control gear need an agent that leaves no residue on the boards. CO2 and Halotron both qualify; the sizing and trade-offs are covered in the sensitive-electronics guide.

Sensitive-electronics guide →

Communication tower sites & shelters

Unmanned equipment shelters run radios, switching gear, and a DC power plant. Motorola R56 and carrier practice keep dry chemical out and put CO2 or clean agent on the wall.

Tower site guide →

Aircraft, hangars & avionics

General aviation owners replacing a dated Halon 1211 unit at the panel reach for Halotron first. It keeps the residue-free, non-conductive behavior around avionics, and NFPA 409 governs hangar coverage.

Aircraft Halotron guide →

Boats, helms & marine electronics

Boat owners protecting the helm and its electronics move off Halon and dry chemical to a residue-free clean agent. The marine guide covers USCG carriage counts and bracket rules.

Marine facilities guide →

Replacing an old Halon unit

If you found a dated Halon 1211 unit near electronics, Halotron I is the clean-agent path most owners evaluate first. It keeps the residue-free, non-conductive behavior Halon was chosen for.

Halon replacement guide →

Flammable liquids in the same space

Where fuel, solvents, or oils sit alongside the electrical hazard, the Class B choice matters too. Compare CO2, Purple K, and dry chemical for the liquid fire.

Class B guide →

Choosing a size

Size is set by the underlying hazard, not by the C rating. Because a Class C fire becomes a Class A or Class B fire once the power is cut, match the unit to the Class A or Class B exposure in the room. A bench or a single rack is usually a 2.5 or 5 lb unit; a room with ordinary combustibles wants an 11 or 15.5 lb Halotron for the added Class A coverage. The lineup table above lists the rating, discharge time, and reach for each size.

For a large open space, a hangar, or a wide switchgear room, a handheld runs out before the fire does. Step up to a wheeled unit, a 65 or 150 lb Halotron or a 50 lb CO2, on a mobile cart with a long hose. See the wheeled extinguisher options or request a facility quote below.

Outfitting a facility or fleet with Class C protection?

Tell us the spaces and the unit count. We will quote CO2 and Halotron clean-agent extinguishers with spec sheets for your fire marshal or insurer, and confirm delivered pricing rather than guessing it at checkout.

or call 714-248-6555 · email partners@usmadesupply.com

Placement basics

Because a Class C fire becomes a Class A or Class B fire once power is cut, NFPA 10 sets travel distance and minimum rating from the underlying hazard in the space, not from the C by itself. The rest of the placement rules are the same as any portable extinguisher:

Mounting height. The top of the extinguisher sits no more than 5 ft above the floor (3.5 ft for units heavier than 40 lb), and the bottom stays at least 4 in off the floor.
Conspicuous and unobstructed. Units are visible, reachable, and along normal paths of travel, with the location marked where it is not obvious.
Match the space, not just the C. A B:C-only CO2 unit does not satisfy a requirement for Class A coverage. Where the room has ordinary combustibles, choose an A:B:C-rated Halotron or pair the CO2 with an ABC unit.

Your authority having jurisdiction, usually the local fire marshal, has the final say on count, rating, and placement.

Frequently Asked Questions

What does a Class C rating on a fire extinguisher mean?

Class C carries no number in front of it. The C means the extinguishing agent is non-conductive and safe to use on energized electrical equipment, so the discharge will not shock the operator. A Class C fire is really an energized-electrical situation; once the power is off, what is left burning is usually a Class A or Class B fire. NFPA 10 and UL 711 define how the rating is earned.

Is a dry chemical (ABC) extinguisher safe for electrical fires?

A multipurpose ABC dry chemical unit does carry a Class C rating, so it is non-conductive and will knock down a fire in energized gear without shocking the operator. The catch is the residue. The powder coats and can corrode electronics, so for equipment you want to keep, a residue-free agent like CO2 or Halotron clean agent is the better choice.

Why does dry chemical damage electronics if it puts the fire out?

ABC dry chemical is monoammonium-phosphate based, a fine powder that works into connectors, boards, and cooling paths. It is mildly acidic and draws moisture from the air, so over the weeks after a discharge it can corrode copper traces and contacts. Equipment that survived the fire can still fail later, and cleaning the powder out of a populated rack is usually a teardown rather than a wipe-down.

CO2 or clean agent (Halotron) for an electrical fire?

Both are residue-free and non-conductive. CO2 costs less and is a common pick for electrical rooms and equipment areas, but it has no Class A rating and it works by displacing oxygen, so ventilate a small closed room before re-entry. Halotron clean agent does not put the fire out by displacing oxygen, so it is a lower asphyxiation risk than CO2 at handheld sizes, and the 11 and 15.5 lb units add a Class A rating that covers ordinary combustibles too.

Does CO2 leave any residue on equipment?

No. CO2 discharges as a gas, smothers the fire, and leaves nothing behind to clean up or corrode, which is why it is used around energized electrical gear. It is rated Class B and C and built to UL 154. Its limits are a shorter reach, weaker performance outdoors or in a draft, and no Class A rating.

Does a clean agent extinguisher also cover ordinary combustibles (Class A)?

The larger Halotron handhelds do. The 11 lb unit is rated 1-A:10-B:C and the 15.5 lb unit is rated 2-A:10-B:C, so both cover Class A wood, paper, and plastics in addition to flammable liquids and energized equipment. The 2.5 lb (2-B:C) and 5 lb (5-B:C) units are Class B and C only, and CO2 has no Class A rating at any size.

What size Class C extinguisher do I need?

Match the underlying hazard, not just the C. Because a Class C fire becomes a Class A or B fire once power is cut, NFPA 10 sets travel distance and minimum rating from the Class A or Class B hazard in the space. For a bench or a single rack a 2.5 or 5 lb unit is common; for a room with ordinary combustibles an 11 or 15.5 lb Halotron adds the Class A coverage. Confirm placement against NFPA 10 and your authority having jurisdiction.

What standards apply to Class C and clean agent extinguishers?

NFPA 10 governs selection, placement, inspection, and maintenance of the portable unit. UL 711 defines how the A, B, and C ratings are tested. CO2 units are built to UL 154, and halocarbon clean-agent units like Halotron to UL 2129. For fixed room-flooding clean-agent systems see NFPA 2001, and for fire protection of IT equipment rooms see NFPA 75.