Is your woodworking shop ready for NFPA 660?

What this NFPA 660 compliance checklist covers

This NFPA 660 compliance checklist covers the ten things that decide whether a woodworking shop is ready for an inspection, an insurance audit, or a bad day.

Each question matches a requirement that comes up again and again in real shops. In fact, the list runs from the paperwork in your office to the dust on top of your light fixtures.

Of course, an NFPA 660 compliance checklist won’t make you compliant by itself. However, it will show you where you stand, in plain language, before an inspector or a fire does.

What NFPA 660 is, and what happened to NFPA 664

NFPA 660, the Standard for Combustible Dusts and Particulate Solids, took effect on December 6, 2024. Basically, it folded six separate NFPA standards into one document.

One of those was NFPA 664, the standard woodworking shops followed for years. Another was NFPA 652, which set the basic rules for every industry that handles combustible dust.

Fortunately, the layout is simple. First come the fundamentals that apply to everyone, such as the Dust Hazard Analysis and housekeeping. After that come the industry chapters. For woodworking, those requirements now sit in Chapter 24 of NFPA 660.

In other words, the rules most shops already knew didn’t disappear. They simply moved. Still, some states and cities enforce NFPA 664 until they formally adopt NFPA 660, so ask your fire marshal which edition applies to you.

Does NFPA 660 apply to your woodworking shop?

If your machines make fine wood dust and your system collects it, the answer is almost certainly yes. After all, fine wood dust burns fast. When it hangs in the air inside a dust collector, it can explode.

Enforcement comes from two directions. First, your state or local fire code adopts NFPA standards, and your fire marshal enforces them.

Second, OSHA inspects for combustible dust under its Combustible Dust National Emphasis Program, reissued on January 30, 2023. That program lists sawmills, lumber resawing and planing, and several kinds of furniture manufacturing among its target industries.

OSHA has no standalone combustible dust standard. Instead, it can cite dust fire and explosion hazards under the General Duty Clause, and it treats NFPA standards as proof the hazard is well known.

Meanwhile, housekeeping problems get cited under OSHA’s housekeeping rule. For real examples, see our list of the top citations to watch out for.

What an inspector asks to see for each NFPA 660 compliance checklist item

Inspectors don’t take your word for it. Instead, they ask for proof. So here’s what each item on the NFPA 660 compliance checklist usually comes down to on a walk-through.

Notice how many of these come down to paperwork. In fact, a shop can do the right things every day and still come up short because nothing is written down.

How the NFPA 660 compliance checklist scores your shop

Every answer on the NFPA 660 compliance checklist earns points. For example, a Yes earns 10, a Not sure earns 4, and a No earns 0. Then your score is the share of possible points you earned, from 0 to 100.

• 90 to 100, Strong footing: the basics are in place. Next, make sure the paperwork backs it up.
• 60 to 89, Gaps to close: you have a foundation. However, at least one gap could turn into a citation or a fire.
• Below 60, High priority: several core protections are missing or unknown. So start with the gap list and bring in an engineer.

Why does Not sure earn partial credit? Because something may already be in place that nobody wrote down. Even so, an inspector treats “I’m not sure” like “no,” so every Not sure lands on your gap list.

Where woodworking shops usually fall short

Most gaps aren’t dramatic. Instead, they’re the slow kind that build up while everyone is busy making product. These come up most often.

• The DHA was never done, or never opened againA DHA is a living document. So if you’ve added machines since it was written, it no longer describes your shop. Read why the DHA is the foundation of safety.
• The shop grew, but the system didn’tAdd a CNC router and two branch lines to an old system, and air speed drops. As a result, dust settles inside the ducts. Check your airflow with our dust collector CFM calculator.
• Plastic pipe and long flex hoseBoth build static charge, and neither can contain a fire. In fact, it’s one of the easiest problems to spot on a walk-through.
• Dust on top of everythingBeams, lights and ledges collect dust for years. Then, in an explosion, the first blast shakes it loose, and that cloud is what levels a building.
• No isolation on the return airSending clean, heated air back into the shop saves real money. However, that return path needs its own protection, designed in from the start.
• Waste handling as an afterthoughtWhen the bin or trailer fills faster than anyone empties it, material backs up into the collector. After all, dust collection should never be the reason your shop stops.
• Collectors moved indoors without a second lookIndoor collectors face tighter rules. Before you bring one inside, read about the NFPA rules for interior dust collection.

Why NFPA 660 compliance starts with your dust collection system

Look back at the NFPA 660 compliance checklist. Explosion protection, isolation, spark control, ductwork and inspections all live in or around the dust collection system.

In other words, most of NFPA 660 compliance is designed in, or designed out, the day the system is laid out.

That’s why we design the whole system around your shop: your machines, your ductwork, your waste and your safety. Every system we design includes safety components and blast gates.

Blast gates close off the machines that aren’t running. As a result, air keeps moving fast enough in the open branches to carry dust out instead of letting it settle.

Likewise, we ask what happens to your waste, and what happens if that stops working. After all, a backed-up collector is both a safety problem and a production problem.

And if your current system isn’t working, we redesign it as a whole. In short, we won’t bolt a new fan onto someone else’s ductwork and hope for the best.

For example, spark control shows why the whole picture matters. Where the detectors go depends on which machines throw sparks and how long the duct runs are. Here’s more on when you need spark detection.

What to do after the NFPA 660 compliance checklist

Of course, a gap list only helps if something happens next. So here’s the order we suggest once you finish the NFPA 660 compliance checklist.

1. Clean up today. Housekeeping is the cheapest fix on the list, and it also lowers your risk right away.
2. Find your DHA, or schedule one. If it’s more than five years old, or you’ve changed the shop since, then it needs an update.
3. Write down what you already do. Often, Not sure answers turn into Yes answers once someone documents the training and inspections that already happen.
4. Get an engineer to look at the system. After all, collector location, explosion protection, isolation and ductwork are design questions, not cleaning questions.
5. Send us your gap report. Finally, use the form above, and a Höcker engineer will review it with you for free.

NFPA 660 compliance checklist FAQs

Sources

• NFPA 660, Standard for Combustible Dusts and Particulate Solids
• OSHA, Combustible Dust
• OSHA Directive CPL 03-00-008, Combustible Dust National Emphasis Program (January 30, 2023)

This page is general guidance for woodworking facilities, not a compliance determination. Your local fire marshal or authority having jurisdiction makes the final call.