Master Lock
Master Lock S3821 Circuit Breaker Lockout Tie Bar 120/240V 1 Pole
A clamp-on lockout device for single-pole miniature circuit breakers rated 120/240V, accepting one padlock with up to 9/32 in shackle
- Secures 1-pole breakers at 120/240 V with clamp-on tie bar
- Accepts one padlock up to 1/4 in shackle for lockout control
- Nylon and stainless-steel body resists impact and corrosion on site
- Bright red and black finish makes lockout point easy to spot
- Compact 3/4 in length fits tight panels without crowding adjacent gear
S3821 Circuit Breaker Lockout
The Master Lock S3821 is a clamp-on lockout device designed for miniature circuit breakers operating at 120/240V. It fits single-pole and two-pole breakers and accepts one padlock with a shackle diameter up to 9/32 inch. Electrical maintenance personnel use it to isolate energy sources during service work.
Clamp-on installation on miniature breakers
The tie bar clamps directly onto the breaker toggle without tools, so installation takes seconds. The thermoplastic body and stainless steel components resist damage in industrial environments. A common issue is verifying that the specific breaker toggle profile matches the clamp geometry before applying the lock.
Check breaker pole count and toggle dimensions
Confirm the target breaker is a miniature type rated for 120/240V with one or two poles. Measure the toggle thickness to ensure the clamp can engage securely. Verify the padlock shackle does not exceed 9/32 inch diameter so it fits through the lockout hole.
Highlights
- Secures 1-pole breakers at 120/240 V with clamp-on tie bar
- Accepts one padlock up to 1/4 in shackle for lockout control
- Nylon and stainless-steel body resists impact and corrosion on site
- Bright red and black finish makes lockout point easy to spot
- Compact 3/4 in length fits tight panels without crowding adjacent gear
Specifications
| Brand | MASTER LOCK |
|---|
Questions about this item
How can I confirm the S3821 lockout is seated correctly on a 1-pole breaker after installation?
The clamp-on design grips the toggle; when the bar lies flat and the padlock hole aligns, the device is properly engaged.
What comes with the S3821 and what must I supply myself?
The lockout body is included; you must provide a padlock with a shackle up to 1/4 in or 9/32 in diameter.
Which version of the S3821 should I choose for a 120/240 V miniature breaker?
This model is built for 120/240 V, 1-pole miniature circuit breakers and accepts one padlock.
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