Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.
Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.
Summary
Every power tool carries a rating plate, and most owners never read past the model number. The same plate lists the electrical rating your tool needs to run, the speed the motor reaches with no accessory fitted, the biggest accessory the tool can safely take, and the marks that show how the tool guards you against electric shock. Reading it correctly is the one page every other power tool page on this site assumes you have already done.
This page will not print a voltage, a current, a speed, or an accessory size for your tool, because every one of those figures belongs to your own model and no other. What this page teaches is which field to look for, what a marking on the plate actually means under OSHA rules, and where the real answer lives: on the plate in front of you. Write the numbers down, and take them to a professional whenever a repair calls for a matching part.
Necessary equipment
| Item | Note |
|---|---|
| Flashlight optional | The print on a rating plate is small and the space is often dark. |
| Camera or phone | Use this to make a photograph of the rating plate. |
| Pen and paper | Use these to record each field from the rating plate. |
| Dry cloth optional | Use this to clean dirt from the rating plate. |
Find the rating plate
Estimated 2 min to 3 min
REMOVE THE BATTERY OR DISCONNECT THE TOOL BEFORE YOU READ THE PLATE.
An unexpected start can injure your hand.
- Remove the battery, or disconnect the tool from the supply.<1mReport a problem with step 1, Find the rating plate
- Find the rating plate on the tool.1mReport a problem with step 2, Find the rating plate
- The rating plate is a label near the motor housing or near the handle.
- A cordless tool can carry a second label on the battery.
- Clean dirt from the rating plate with a dry cloth.<1mReport a problem with step 3, Find the rating plate
- Point a light at the rating plate from one side.<1mReport a problem with step 4, Find the rating plate
- Light from one side makes the print easy to read.
- Light from the front causes a reflection.
Read the electrical rating
Estimated 1 min
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
CONNECT A CORDED TOOL ONLY TO A SUPPLY THAT MATCHES THE RATED VOLTAGE ON THE PLATE.
A wrong supply can shock or burn you.
- If the tool has a cord, find the rated voltage on the plate.<1mReport a problem with step 1, Read the electrical rating
- The rated voltage is the supply voltage the tool needs.
- If the tool has a cord, find the rated frequency on the plate.<1mReport a problem with step 2, Read the electrical rating
- The frequency uses the unit hertz, or Hz.
- Find the rated current on the plate.<1mReport a problem with step 3, Read the electrical rating
- The rated current uses the unit amperes, or A.
- The rated current sets the minimum wire size for an extension cord.
- If the tool is cordless, find the rated voltage on the battery.<1mReport a problem with step 4, Read the electrical rating
- A cordless tool can show this rating on the tool, on the battery, or on both.
Read the speed rating and the accessory limit
Estimated 1 min
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
DO NOT FIT AN ACCESSORY RATED BELOW THE SPEED ON THE PLATE.
The accessory can fail and injure you.
- Find the no-load speed or the rated speed on the plate.<1mReport a problem with step 1, Read the speed rating and the accessory limit
- Manufacturers show this value in revolutions per minute, or RPM.
- A tool with a speed dial can show a speed range instead of one number.
- Find the maximum accessory size on the plate.<1mReport a problem with step 2, Read the speed rating and the accessory limit
- The plate can show a maximum blade diameter or a maximum wheel diameter.
- Compare the speed rating on the plate with the rating on each accessory.<1mReport a problem with step 3, Read the speed rating and the accessory limit
- Choose an accessory with a rating at or above the speed on the plate.
- A federal rule on machine speed requires this check before you fit an abrasive wheel.
Read the insulation symbol and the listing mark
Estimated under a minute
DO NOT REMOVE THE GROUND PIN FROM THE PLUG OF A GROUNDED TOOL.
Without this pin, the tool can shock you.
- Find the double insulation symbol or the ground symbol on the plate.<1mReport a problem with step 1, Read the insulation symbol and the listing mark
- The double insulation symbol is two squares, one inside the other.
- A double insulated tool has extra insulation. It needs no ground wire.
- Find the listing mark from a national testing laboratory.<1mReport a problem with step 2, Read the insulation symbol and the listing mark
- OSHA accepts a mark from UL or from FM as an approved mark.
- The listing mark shows that an independent laboratory tested the tool.
Record the model number and the serial number
Estimated 2 min to 3 min
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
DO NOT GUESS A CHARACTER YOU CANNOT READ ON THE PLATE.
A wrong model number can give you the wrong part.
- Write the brand name from the plate.<1mReport a problem with step 1, Record the model number and the serial number
- Write the model number from the plate.<1mReport a problem with step 2, Record the model number and the serial number
- Copy each character exactly as it appears.
- The letter O and the number zero are easy to confuse.
- Write the serial number from the plate.<1mReport a problem with step 3, Record the model number and the serial number
- A cordless tool can show a separate serial number on the battery.
- Make a photograph of the whole plate.<1mReport a problem with step 4, Record the model number and the serial number
After the job
Estimated under a minute
- Keep your written record and your photograph with your tool documentation.<1mReport a problem with step 1, After the job
- Give this record to a professional before you order a part.<1mReport a problem with step 2, After the job
Terminology
This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.
- rating plate
- Also called: nameplate, name plate, data plate, spec plate, specification label, tool label, ID plate, what does the label on my drill mean
- no-load speed
- Also called: free speed, no load RPM, unloaded speed, top speed with nothing attached
- rated voltage
- Also called: input voltage, operating voltage, voltage rating, what voltage is my drill
- rated current
- Also called: amp draw, amperage rating, current draw, tool amp rating
- double insulation symbol
- Also called: double insulated symbol, square in a square, two squares symbol
- listing mark
- Also called: UL mark, safety certification mark, NRTL mark, testing lab mark
When to use a professional
This page reads a label. It does not open, adjust, or repair the tool.
Stop if you cannot read a character on the plate. Give the tool to a professional who has the tools to read a worn plate.
Speak to a qualified electrician before you change a plug or use an adapter. A qualified electrician must judge if the change is safe.
Give a professional your written record and your photograph. This record can save a second visit to the same plate.
Common questions
What does the rating plate on a power tool actually tell you?
It is the manufacturer's own label, usually near the motor housing or the handle, and it carries the facts that describe your exact tool: the brand, the model number, the serial number, the electrical rating it needs, the speed the motor reaches with nothing attached, the biggest accessory it can safely take, and the safety marks that show how it guards you against electric shock. This page walks through each field so you know what to look for. It will not hand you a made-up number for your model — read the real figure off your own plate.
What does no load speed mean?
It is the speed the motor reaches with no accessory attached and no material in contact with it, usually shown in revolutions per minute, or RPM. Manufacturers print it on the rating plate so you can compare it against the speed rating on an accessory before you fit it. OSHA's rule on abrasive wheels, 29 CFR 1910.243(c)(5)(i), requires exactly this check: the spindle speed of the machine must be checked before mounting the wheel, to make sure it does not exceed the maximum operating speed marked on the wheel.
What is the double insulated symbol on a power tool?
It is two squares, one drawn inside the other. OSHA describes a double-insulated tool as one built with a special insulating system used instead of a grounding wire, and a tool that carries this symbol and the words "double insulation" or "double-insulated" needs no separate ground wire. Look for it near the electrical rating on the plate, often next to a plug or wire symbol for a tool that is grounded instead.
Does a double insulated tool ever still need a ground wire?
No, but the double-insulation option itself is not unlimited. OSHA's own guidance on a related construction wiring standard states that double insulation is allowed instead of grounding only within limits: double insulated tools are not for a hazardous location, and the standard sets a ceiling of 150 volts to ground for the exception to apply. That figure is this one standard's own stated ceiling for its own exception. It is not a number printed on any tool's plate, and this page does not ask you to read one.
What is a UL listing mark, and why does it matter?
It is a mark from a nationally recognized testing laboratory, such as UL or FM, showing that an independent lab tested the tool. OSHA defines an "approved" tool as one accepted, certified, listed, or labeled by a qualified testing laboratory, and OSHA's own guidance says this listing mark, together with the double insulation marking or a proper ground, is what identifies a tool as acceptable. Look for it near the double insulation symbol or the ground symbol.
Where do I find the amp rating for choosing an extension cord?
On the rating plate, usually next to the rated voltage. The rated current, in amperes, is the figure an extension cord has to be sized around; a cord that is too light for that current can overheat under load. This page only teaches you where to find that number. The separate record on choosing an extension cord for an appliance covers the sizing itself, so the two pages do not repeat the same explanation.
Related procedures
- How to find and record the model and serial number of every appliance in the house
- What size blade fits my circular saw, and does the RPM rating on the blade matter?
- How do I check if a grinding wheel or cutting disc is safe to use on my angle grinder or bench grinder?
- How do I read the label on my hot water heater and figure out what the numbers mean
- What drill bit and what speed should I use for wood, metal, plastic or concrete?
- How old is my water heater and how do I read the serial number
- How do I decode the date code on my appliance and find out how old it is
- Identify a lost power adapter from the equipment's own marking, and match a replacement
Sources
Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.
- Tier 11926.302 - Power-operated hand tools.
- Tier 1Marking recognition, regulations and policy of double insulated power tools
- Tier 1All electric tools need to be tested by a qualified national testing laboratory and be listed and labeled
- Tier 129 CFR 1910.243 — Guarding of portable powered tools
- Tier 1Electric power tools: grounding, NRTL approval, and suitable circuit connection.
Revision history
Current version 1 · updated 2026-08-04 · next review due 2027-08-04
- v1 · 2026-08-04First draft. Covers the fields a reader can expect on a corded or cordless power tool's rating plate: rated voltage, rated frequency, rated current, no-load or rated speed, maximum accessory size, the double insulation symbol or ground symbol, and the listing mark from a national testing laboratory, plus the model number and serial number. Grounded in five OSHA regulations and standard interpretation letters, all fetched directly and read in full (not through a summarizer): 29 CFR 1926.302(a)(1) on double-insulated-or-grounded construction; 29 CFR 1910.243(c)(5)(i), quoted verbatim, 'The spindle speed of the machine shall be checked before mounting of the wheel to be certain that it does not exceed the maximum operating speed marked on the wheel' (source id osha-1910-243-guarding-portable-powered-tools, an already-registered source; this record's own quote comes from paragraph (c)(5)(i), a different paragraph of the same document from the (a)(1) saw-guard text that source's existing notes quote — both paragraphs are part of the one registered URL); and three interpretation letters on double insulation marking, testing-laboratory approval, and the stated limits of the double-insulation exception. No tool-specific safety-critical figure (voltage, current, speed, accessory size) is asserted as a general value; every such field publishes as an instruction to read it from the reader's own plate, per rule 1. Written to be the prerequisite page for choose-an-extension-cord-for-a-power-tool and inspect-a-bonded-abrasive-wheel-before-you-fit-it per the backlog note, without repeating either page's own explanation (rule 7).
Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.
Comments and corrections
Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.
Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.