jk jigger
JK JIGGER FITTING INSTRUCTIONS
(Main Switch/Isolator Safety Shaft Blast Suppressor)
In environments prone to explosions or extraordinary sudden vibration, electrical enclosures are often used to supply power & control circuits for electrically driven machinery (drill rigs), pumps, ventilation fans etc, particularly in the mining industry. On average most of the time these power & control boxes function as designed without any problems. However occasionally these power & control boxes are located in a convenient position for the Rig operator but also may be exposed to percussion blast pressures when a heading is fired. In this situation if the power & control box is too close & susceptible to the extraordinary blast pressures the Main Switch/Isolator handle is often blown or broken off the power and control box. Thus after a blast when work re-commences operators may not be able start up as the power and control box will be in an unsafe condition.
NOTE: If the switch can no longer determine On or Off as according to ASNZS 3000-2007 regulation number 2.3.2.2.1(c) states Devices for isolation, clearly and reliably indicate the isolating position of the device; The symbols ‘O’(OFF) and ‘I’(ON) are deemed to satisfy this requirement.
* The operator does not know if the power is switched on or off, regardless of whether the power and control box is rendered “Out of Service” until it is repaired. This incurs downtime in loss of production (drilling time) or may leave a pump or fan unable to be isolated by anyone but an electrician this can be hazardous at any time, also incurring unnecessary down time for the electrician to replace the ON/OFF isolator handle plus the cost of the new ON/OFF isolator handle.
* The isolator ON/OFF handle is blown or broken off because the blast pressure is both negative and positive effectively compressing then expanding the enclosure instantaneously. The most vulnerable part of the box which may flex due to the blast pressures is the door which has the Main switch isolator ON/OFF handle mounted on the front of it but also fits onto a solid MAIN ISOLATOR extension shaft not having any tolerance to allow for the door to flex in & out thus breaking the ON/OFF handle.
Some of these enclosures have an equalizing air type valve on the side of them allowing air to flow in and out thru a filter; this may reduce the above effect to a small degree.
* The JK Jigger will allow approximately 20mm in both directions (in & out). It can be retrofitted in most cases in the place of the existing isolator shaft in the time it takes to remove the existing isolator shaft, measure and cut the new JK Jigger the same length, reinsert the new JK Jigger and secure in position.
* The Jk Jigger has 8 different designs to suit most handles in the industry. It has been manufactured with a 6,8,10,12 mm, and a combination model 10 to 12mm shafts to suit SACE/TMAX and Stromberg.
In most enclosures it will be a quick and painless changeover, however in some enclosures the extension shafts are not accurately aligned with the main switch ON/OFF handle this may be due to the switch plate on the face of the circuit breaker being worn or sloppy due to natural wear and tear or excessive forces from being in such a harsh environment. This may need to be replaced or the position of the handle may have to be moved to allow the new blast suppressor extension shaft to lodge unobstructed into the rear of the ON/OFF handle so normal operation can be achieved.
Eliminate broken handles and power outages!
Estimated JK Jigger cost savings at your mine ...
| Amount of Handles damaged/year | 10 Per Year |
50 Per Year |
100 Per Year |
| Broken handles replacement and labour cost | $2,200 |
$11,000 |
$22,000 |
| Cost of Lost opportunity (Operating downtime etc.) | $2,000 |
$10,000 |
$20,000 |
| Total loss every year | $4,200 |
$21,000 |
$42,000 |
| Approx. cost of JK Jiggers (once off purchase) | $2,400 |
$12,000 |
$24,000 |
| Total yearly savings (Saving less cost of Jiggers first year) | $4,200 |
$21,000 |
$42,000 |
| Total savings 10 years | $42,000 |
$210,000 |
$420,000 |
