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The Master Lock 493B Circuit Breaker Lockout is a compact, durable safety device designed to securely lock standard single and double toggle breakers on 120V and 240V circuits. Featuring a patented Grip Tight™ mechanism, it ensures quick, reliable lockout with a simple thumb turn and clamp. Constructed from powder-coated steel and reinforced polymer, it withstands tough environments and integrates seamlessly into OSHA-compliant lockout tagout safety programs.

| ASIN | B004J173I8 |
| Best Sellers Rank | #4,384 in Industrial & Scientific ( See Top 100 in Industrial & Scientific ) #2 in Lockout & Tagout Devices |
| Brand | Master Lock |
| Circuit Breaker Type | Standard |
| Current Rating | 24 Amps |
| Date First Available | May 25, 2017 |
| Global Trade Identification Number | 00071649229725 |
| Is Discontinued By Manufacturer | No |
| Item Weight | 1.76 ounces |
| Item model number | 493 |
| Manufacturer | Master Lock |
| Mounting Type | Tie-bar |
| Number Of Poles | 1 |
| Product Dimensions | 5"D x 3"W x 1"H |
| UPC | 071649229725 |
| Voltage | 240 Volts |
A**Z
So Simple And Effective
I bought this breaker lock-out as a reminder to not turn this breaker on, unless you really need it. I use this on the 240V, 50 AMP, Electric Vehicle / Recreational Vehicle outlet that I installed under our breaker panel. Most of the time, this should be turned OFF, but on rare occassion it needs to be turned on. This Lock-out makes it really easy to remember to keep it turned Off when not needed and prevents people from turning it on by accident. The quality of construction is excellent and although I didn't need to use the fitment accessories that came with it, I appreciate that they were included. Nothing is as frustrating as not being able to finish a project beause of a fitment issue. Master Lock had this in mind and they have you covered. Great little product. I would definately buy it again.
N**J
Great Product
I'm an electrician, I use these whenever I work on a job. It keeps someone from flipping on the breaker while I'm working on the circuit. They work perfectly.
J**3
Simple Solution
Simple circuit lock. Easy to use. It does inhibit me from closing box cover due to height when it's attached to breaker but that is no fault of the product. Very happy with purchase.
C**R
Not for 4-pole breakers with pairing braces
I bought this lockout for a four pole quadplex breaker. I wanted to shut off the inner toggles of a 240 volt, 40 amp breaker (see pictures). Because the outer metal pairing brace (AKA "that metal thingy"), the lock wouldn't engage with the inner two 40 amp toggles. The description does mention working with tie-bars such as what I have with the 40 amp toggles but when the outer metal pairing brace also exists, this lockout won't work. I've included some pictures that illustrate the problem. Dare I say better pictures than the seller provided. Although this device won't work for me, it seems to be a decent product. I am able to lock out single pole toggles ok. The grip of the toggle is pretty strong. Tighten with the thumbscrew. Then when you swing down the arm, it increases the pressure and it would take some work to pull it off. It might not be suitable to lock out a breaker from a neighbor stealing power but in a safety situation it should be fine. I'm going to keep this lockout for other breakers. I dropped a star mainly because the description is ambiguous, not because the device is poor.
R**B
Works on Residential Breakers
Works on residential breakers. Make sure you use the included bands to make sure the device has enough surface friction to grip. Great for locking out a breaker that leads outside during a project
C**M
Exactly the same
Perfect. Not cheap plastic. It’s exactly as it should be. And it saves you $15 compared to the warehouse prices
D**K
Best for small breakers
Simple to use and reliable. Turn to knob until the pads touch both sides of the breaker, close the cover and it clamps down. Simply, easy, reliable.
D**E
Might work for you, but didn't for me...
These lockout clamps are well made, and seem to grip the breaker switch securely. They could probably be pried-off, but I'd think doing so would be just as likely to break the switch, so I think it's just fine in that respect. However, in my application - a 20-year-old GE panel - when you close the hasp, it trips the breaker switch on the opposite side of the panel, i.e. there isn't enough room to close the hasp without hitting the opposing breaker switch. There would be enough room to lock the breaker in the on position, but not in the off position. If you hacksawed-off the hasp, it would work just fine, and if you're not intending to put a lock or tag on it, that would solve the problem for you. On my 10-year-old Square-D sub-panel, these do fit - they clear the opposing breaker by about a millimeter. They do not fit on the arc-fault breakers I have, which have a raised portion on the "off" side. Clearly these work for some people, and maybe they will for you, but they didn't work on either of my panels.
E**.
Muy buen producto para el trabajo
E**A
Me parece de buena calidad y robusto. un poco caro pero contento con la compra
H**F
Commande reçu à temps et quantité exact contrairement à d’autre. Top top
P**E
Good breaker lock like the snug fit
R**R
Worked perfectly for my job. Allowed me to lock out 575v circuit breaker without problems
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