The Henry Krank Alarm Mine is a trip-wire operated device to warn of intruders, when triggered, the device detonates a 12g Black Powder Blank, giving off a sound like a shotgun blast and warning the landowner.

It is useful for securing areas, providing an instant warning of trespassers and giving intruders a visible and audible deterrent. Invented and produced in house, the Alarm Mine is known the world over for its robust value, simplicity, and effectiveness.

Alarm Mine Sign


How does the Alarm Mine work?

It works, simply, by a trip wire. The Alarm Mine unit is a solid aluminium body, with a spring-loaded firing pin, that will accept on one end, a 12g black powder blank, and the sear and wire on the other.

The device is operated by screwing the Alarm Mine unit, using the supplied screws, on to a sturdy (preferably vertical) support, such as a wooden fence post. The spring is then retracted until the sear notch is visible on the firing pin rod, into which the sear is inserted, with the wire run across the distance to be guarded. The wire can either be wrapped round another object and returned, with the trailing end fixed just behind the sear with the included safety pin, or attached at its full length to a nail, hook or similar.

Once the device is fixed in position, a 12g black powder blank may be placed in the vacant slot at the other end of the device. At this point, the device is armed and any pressure on the trip wire will cause the device to detonate the blank.

When properly secured, about 1.5lb of force is required to trip the wire, so it is sturdy enough for outdoor use and will not be triggered by high winds, but light enough to be triggered by the smallest human or animal touch.

The trip wire supplied with the Alarm Mine is translucent (similar to fishing line), and next to invisible when placed.

The body is supplied with wood screws, for screwing directly into fence posts or similar, however the mine can be used on any appropriate surface, so long as it is attached sturdily.

It is recommended to wear eye and hearing protection when fitting the device, and not to place the Alarm Mine near potentially flammable substances, as there is a significant fire risk from the black powder blanks if detonated.

Henry Krank Alarm Mine


Is the Alarm Mine legal, or not?

The Alarm Mine is of course perfectly legal. It is ideally suited to guarding fences or similar, and should never be placed across doorways. It should always be used in conjunction with our alarm mine warning signs.

The Alarm Mine should never be used with live cartridges, as these give the potential to injure, blanks must always be used. Care must be taken that warnings are in place, are visible to any would-be trespasser, and the Alarm Mine is not placed in any place where injury may result, as the user may be liable for harm to the trespasser.



How is the Alarm Mine best used?

It is perfect for farmers and gamekeepers wishing to control the boundaries of their land, it can be placed across fence posts to provide an instant and audible indication of an intruder.

It has also found favour with vehicle owners wishing to protect their car or motorcycle, and we have even sent these as far afield as Canada, for people wishing to protect their smallholdings against bears! The Alarm Mine has found favour wherever used, and is highly recommended by Crime Prevention Officers.


Who is the Alarm Mine useful to?

The Henry Krank Alarm Mine is useful to anyone wishing to protect their land or secure a particular area of their property. It can be used to protect against poachers or burglars, and may be placed covering a fence or other point of entry. It is important the Alarm Mine is not placed to cover any door, path, or easement.

Fenced Gate


How to buy the Henry Krank Alarm Mine

The Alarm Mine and Alarm Mine warning signs are available on our website, or can be ordered over the telephone. The 12g Black Powder Blanks are also available online, however a delivery surcharge will apply, as these are explosive.

We have spare sears, wire and screw packs, blanks and signs constantly in stock. Please see the links below to all products mentioned in this blog.

The complete Alarm Mine unit (minus blanks)

12g Black Powder Blanks

Warning Sign

Spare Sear

Spare Wire, Screw & Sear Kit