A push button lockout is a cover or clamp that sits over a button head so the button cannot be pressed while your team is working on the machine. You install it after the equipment has been isolated through your normal energy control procedure: you place the device over the button, secure it, and apply your own padlock so only you hold the key. You remove it once the work is finished, the affected workers are accounted for, and the responsible person confirms it is safe to restore energy. The device itself does not cut power — it simply blocks the button from being operated until the lock is taken off by an authorized person.
A push button lockout does one job well: it creates a physical barrier between a person’s hand and the button, so the emergency stop or control button cannot be triggered by accident or without intent. It is a visible, tamper-evident layer that tells anyone on the floor “this button is locked out.” If you are new to the category, our push button lockout guide explains the different body styles in more detail.
What it does not do matters just as much. A button lockout is not, on its own, an energy isolation device. It does not de-energize the circuit, bleed down stored pressure, or replace the lockout tagout (LOTO) steps your procedure already requires. It is one component of a larger control method, used after the primary isolation is in place. Treating it as the only safeguard is a common and serious mistake, which we cover later in this article.
Most round mushroom-head buttons share a similar shape, and a emergency stop button lockout is built to cover them. A button switch lockout SBL31 handles standard boat shape switch, while the larger emergency stop models cover 22.5 mm, 25.5 mm, and 30 mm heads. When you are specifying a control panel button lockout, the deciding factor is almost always the measured diameter of the button, not the label on the panel.
This is the core of a lockout for press-type and twist-release buttons: the same clamp-style body works across both release styles as long as the head diameter and the bezel shape fall inside the model’s stated limits. Always confirm the diameter before you order, because a device that is a few millimetres too small will not seat, and one that is too large may leave the button partly exposed.
Before you fit anything, measure three things. First, the button head diameter — the widest part of the round cap, commonly 22 mm, 22.5 mm, 25.5 mm or 30 mm on an emergency stop, and much smaller on a control button. Second, the bezel clearance — the flat space (or raised collar) around the button where the lockout body needs to grip. Third, the panel space — whether there is room beside the button for a padlock shackle and a lockout hasp if more than one worker is involved.
Getting the push button lockout sizes right the first time saves a return trip to the storeroom. The quick check below walks you through the decision so you can match a model from the comparison table further down.
If the button is a small control panel switch rather than a mushroom-head emergency stop, a button switch lockout such as the SBL31 is the usual match. Its base measures about 31.8 × 25.8 mm and it accepts a padlock shackle up to 7 mm. If it is a larger mushroom-head emergency stop, continue to Step 2 to measure the head diameter.
22 mm heads suit the SBL41. 22.5 mm heads suit the SBL01-D22 or the SBL05-06. 25.5 mm heads suit the SBL01M-D25. 27.5 mm heads suit the transparent SBL51. 30 mm heads suit the SBL02-D30, the SBL41, or the SBL05-06.
Confirm the lockout body can sit flush against the panel and that there is space for your padlock shackle (and a hasp if several workers lock out). If the collar is unusually tall or the button sits in a recessed guard, note the measurements and send them to the supplier before ordering.
The phrase how to install push button lockout really means “fit it after isolation, then lock it.” Follow the same order every time so the step becomes a habit for your team. This push button lockout installation sequence assumes the machine has already been shut down and its energy sources isolated under your site procedure.
The same fitting logic applies to other electrical isolation points. If your panel also has breakers that need covering, our guide to circuit breaker lockout devices walks through choosing those devices by breaker type.
Knowing how to remove push button lockout devices is just as important as fitting them, because removal is the moment energy is about to return. Keep the rule simple: the person who applied the lock is normally the person who removes it, and only after the work is verified complete.
In short, removal is an authorized action, not a casual one. Only workers named in the energy control procedure should take a lock off, and the restoring step follows the procedure rather than the lock.
A good button lockout is quick to fit — that is a real advantage on a busy floor where every minute of downtime costs money. But “easy to fit” and “easy to remove” are two different things. The speed of installation comes from a well-shaped body and a simple clamp; the control over removal comes from the padlock, which only the authorized person can open.
Your business should treat the two separately. Train your team so that anyone can fit a device under supervision, but only the assigned worker (or the procedure’s authorized person) removes the lock. A device that snaps on in seconds is not a weakness as long as the key stays with the right person and the tag stays on the panel. The convenience is in the fitting; the control is in the lock.
Most problems with button lockouts come from a handful of repeatable errors. Watching for them helps your seven-step lockout tagout procedure stay intact.
The table below lines up the Prolockey models most often used for button and emergency stop lockout. Diameters reflect the product descriptions; always re-check the specific head and bezel on your panel before ordering. For a larger 30mm emergency stop lockout or a 22mm push button lockout, the SBL series covers the common sizes directly.
| Model | Fits Button Diameter | Button Type | Notes |
|---|---|---|---|
| SBL01-D22 / SBL01M-D25 / SBL02-D30 | 22.5 mm / 25.5 mm / 30 mm | Press or screw emergency stop | Fixed-size covers for the three common e-stop heads. |
| SBL41 | 22 mm and 30 mm | Emergency stop | One body covers both 22 mm and 30 mm heads. |
| SBL51 | 27.5 mm | Emergency stop | Polycarbonate body. |
| SBL05-06 | 22.5 mm / 30 mm | Emergency stop | Wider transparent body covers 22.5 mm and 30 mm heads on larger panels. |
It is a cover or clamp placed over a button head — usually an emergency stop or a control panel button — to stop the button from being pressed while maintenance or service work is carried out. It is used as part of a lockout tagout procedure and is locked with a padlock applied by an authorized worker.
After the machine is isolated, place the device over the button head so it fully encloses the cap, secure the body, and apply your own padlock. For twist-release buttons, make sure the body also blocks the turning motion. Confirm the button cannot be pressed before you start work.
Removal happens only after the job is verified complete and all affected workers are accounted for. The worker who applied the lock normally removes it, then the device is taken off and energy is restored following the site procedure — not by whoever took the last lock.
Generally the person who applied the lock, or the authorized employee named in the energy control procedure. Removing a lock is a controlled action tied to the procedure, not something any passer-by can do.
Yes, for round mushroom-head buttons within the model’s diameter range. The product descriptions refer to “press or screw” emergency stop buttons, meaning both press-to-activate and screw/twist-release styles can be covered as long as the diameter and bezel fit.
No. A button lockout blocks the button from being operated but does not de-energize the machine or control other energy sources. It is applied after the primary isolation in your lockout tagout procedure, not in place of it.
On a single button lockout, one padlock is typical, but when several workers are exposed you would normally use a lockout hasp or group lockout box so each person can apply their own lock. The device then cannot be removed until every lock is taken off.
Choosing the right push button lockout comes down to three things: measure the button head accurately, match the model to that diameter, and keep removal tied to your authorized energy control steps. A device that is quick to fit should never become quick for the wrong person to remove.
| Not sure which push button lockout fits your control panel? Send Prolockey photos of the buttons and their diameters, and we can match a suitable model. |
