TOWER. Hirwaun, Glamorganshire. 12th. April, 1962.

The Tower Colliery was in the No. 4 Area of the National Coal Board’s South Western Division and was situated at the village of Hirwaun about four miles from Aberdare. The seams that the colliery worked were close to the bottom of the coal measures and it was centrally placed along the northern outcrop of the coalfield. Records showed that coal was first mined in 1864. The “take” of the colliery traversed three large faults which naturally divided the mine into three parts. The natural division and a scheme of reorganisation and modernisation had resulted in the mine being served by six cross measure drifts from the surface and three vertical shafts. The colliery produced about 1,500 tons a day and employed 938 men underground and 234 at the surface.

The ventilation was produced by two fans. At the No.1 upcast shaft a Sirocco single inlet fan produced 95,000 cubic feet of air per minute at a water gauge of 4.1 inches and at the No. 4 upcast shaft a similar fan produced 180,000 cubic feet of air per minute at a water gauge of 2.8 inches.

Safety lamps were used throughout the mine. For general lighting the Oldham Wheat W type electric lamp was used. Senior officials and deputies used Thomas and Williams Cambrian type No.8 flame safety lamps and Thomas and Williams type No.1 flame lamps were used as gas detectors by appointed workmen. The seams that had been worked in the life of the colliery in descending order where the Four feet, the Six Feet, the Red Vein, the Nine Feet, the Bute, the Seven Feet and Five feet. At the time of the explosion the Nine Feet, Seven Feet and Five Feet Seams were being worked. Mr T. Wright was the Area General Manager, Mr. P.R. Weekes the Area Production Manager, Mr. V. Lewis, the Deputy Area Production Manager (Operations), Mr. S. Thomas the Deputy Area Production Manager (Planning) and Mr. T.G. Jones the Group Manager. The Manager of the colliery was Mr. J. T. Ryder and there were three undermanagers of whom Mr. C.J. Bell was responsible for the area affected by the explosion. This part of the mine was known as “Tower 4” and was served by the No.3 Drift and the No. 3 New Drift and intake airways and the No. 4 upcast shaft. It was known as the “G” panel and was in the nine Feet Seam.

The “G” panel was developed following the establishment of a new ventilation circuit of which the no. 3 New Drift formed the main intake with a main return airway by way of a cross measure driven to the No. 4 upcast shaft. From these main airways, two levels at 30-yard centres were driven on the strike of the seam to the limit line of the working 850 yards inbye. In this area the Nine Feet Seam was found to vary little in thickness, 7 feet 6 inches, with a strong clift roof and a hard fireclay floor. At the time of the explosion, there were two working places in the panel. One to the dip from the levels and worked by a Continuous Miner and was called the “Miner” heading which was not affected by the disaster. The second working place was developed near the inbye end of the levels to the rise. This heading was known as MC3 which was the area where the explosion occurred.

The panel was under the supervision of an overman and a deputy on the morning shift and on the afternoon and night shifts by deputies and the assistance of an overmen who also had responsibility for other districts. On each shift there was shotfirer and a second official with the status of deputy was employed in the “Tower 4” part of the colliery to closely supervise the arrangements for the ventilation of the several narrow drivages.

The MC3 heading had been driven at a rising gradient 1 in 10.5 in the full thickness of the seam for 328 feet and was 12 yards wide. The coal was won by shotfiring out of the solid coal and loaded on to a short scraper chain conveyor by a Sampson MC3 Loader. The conveyor delivered the coal to a belt conveyor down the heading which in turn fed the main gate belt conveyor in the return level. Coal was worked on each of the three shifts. The support in the heading was by straight H section girders, 6 inches by 5 inches, carried on wood props set at the roadsides.

All the machinery in the heading was electrically driven and supplied from a 300 kVA 3300/550-volt flameproof transformer in a substation in the “G” return roadway about 500 yards outbye of the MC3 heading. The neutral point of the 550 volts winding was earthed. On the primary side of the transformer there was an oil-immersed circuit breaker which was fitted with time-lagged overload trips set at 50 amps. and an instantaneous earth leakage device connected to a current transformer in the secondary neutral lead. this was arranged to trip the circuit breaker when a current of 2.5 amps flowed from phase to earth in the 550-volt system.

The secondary side of the transformer was connected by a short length of 0.15 square inch paper insulated, lead covered, double wire, armoured cable to a flameproof air-break section switch in the same substation. This switch was provided with an isolator and a hand-operated circuit breaker, and was fitted with thermal overload trips set at 142 amps, instantaneous earth leakage device designed to trip when a current of 3.5 amps flowed from phase to earth. the earth leakage devices were designed to trip and lockout automatically he respective switches on the occurrence of an earth fault on the 550 volts system and to indicate, by means of a visible flag, that a fault had occurred. A test button was also provided on each switch so that the correct functioning of the devices could be tested.

An armoured cable from the section switch passed inbye along the return to a flameproof gate end switch controlling the “Miner” heading conveyor. The supply was looped through the busbars of this switch to a coupling box from which the “Miner” was supplied and the cable continued to the MC3 heading and a flameproof gate end switch controlled auxiliary fan and the MC3 belt conveyor. Both these switched were in the return roadway a few yards from the entrance to the MC3 loader. From the last switch the cable passed up the heading to two coupled gate end switches placed 20 yards back from the face. One of these switches controlled the scraper chain conveyor and the other the MC3 loader. The feeder cable was connected at the end of the busbars of these switches and was looped back on itself.

The MC3 heading was ventilated by a 16-inch diameter Meco axial flow auxiliary fan which forced the air from the intake level through ducting which was 20 inches in diameter. The fan was in the connection between the intake and the return levels about 12 yards outbye of the MC3 heading. The manager had set a minimum quantity of 2,100 cfm to be delivered to the face.

On the night shift immediately prior to the disaster, coal had been filled normally for the first half of the shift but was interrupted by a mechanical breakdown of the MC3 loader. The fault could not be rectified quickly and it was decided to complete the shift by shortening the scraper chain conveyor and lengthening the belt conveyor. The work had not been completed at the end of the shift and was carried on during the morning shift when the normal workforce of seven in the heading was added to by two persons from other districts, as well as two fitters who were working on the CC3 loader and the ventilation official, who was later joined by three electricians. Two representatives of the workmen were approaching the heading along the return roadway on inspection duties.

The movement of the conveyors made it necessary to move forward the two coupled gate end switches which controlled the scraper chain conveyor and the MC3 loader required the addition of a new length of cable. Electricians, N. Lewis, (Class I), T. Davies (Class II) and an apprentice, M.A. Pearce were instructed by the electrician, in charge of the mine, to move the switches and extend the cable. Some difficulty had occurred with a pump in another part of the mine and Lewis had first to attend to that. He made sure that Davies knew how the work should be done in the MC3 heading and told Davies and Pearce to go to the heading and make a start.

Davies arrived at the “G” panel at about 8 a.m. and found the undermanager, C.J. Bell, in the “Miner” heading. After some discussion, Davies cut off the power at the section switch in the substation for both the “Miner” heading and the MC3 heading, removed the connecting pins in the box near the top of the “Miner” heading and restored the power at the section switch. This cut off all power to the MC3 heading without interfering with the supply to the “Miner” heading which was able to carry on working. This was at about 9 a.m.

Davies and Pearce then proceeded to disconnect the gate end switch in the MC3 heading and had almost completed the work when Lewis arrived back. He left Pearce to complete the work and Lewis and Davies made a test on a length of cable to be installed, which, at the time was lying alongside the main conveyor in the return roadway. They found the cable to be satisfactory and Lewis secured a chain to the end of the cable which was then dragged by a horse for a distance of about 100 yards up the MC3 heading to its new position. This was a few minutes after 10 a.m.

The underground manager, Mr. Bell, arrived in the heading at this time and was told by the deputy in charge, K. Strong, that the auxiliary fan had been stopped for 15 minutes. The Inspector, Mr C. Leigh commented:

This statement was hard to believe since the power had been cut off at 9 a.m.

Five or six yards back from the face Bell found a concentration of gas near the roof which he estimated at two per cent. He instructed the deputy to send everyone except the electricians back to have their food at the bottom of the heading while he remained with the electricians until they completed the connecting of the switch. This was done and he came out of the Heading with the electricians.

Lewis and Davies, having first cut off the power at the section switch in the substation, restored the connecting pins at the box at the top of the “Miner” heading and went back to the section switch to restore the power to the whole of the “G” panel. They had not made any tests of the re-erected apparatus.

Davies was the first to reach the section and stated that he tried to close the switch but failed because he “was too quick”. Lewis closed the switch. He stated that he was watching the ammeter expecting to see the indication of the load of the auxiliary fan starting up when the explosion occurred. At this point he put the switch out. This was at 10.30 a.m.

The undermanager was in the intake level and went back to the scene with the overman who had been in the “Miner” heading throughout the shift. He telephoned the manager to inform him and then went some distance up the MC3 heading so as to be sure that there was no one there. He found the heading too full of dust to be sure that there was no one there. He saw no sign of flame or burning of any description and the normal ventilation was only interrupted for a moment. The manager immediately went to the scene with other officials and workmen gave first aid treatment to the injured and arranged for them to be taken to the surface.

The Dinas Permanent Rescue Station was informed and the brigade arrived without delay and made an inspection of the heading. Later other brigades assisted in re-establishing the ventilation in the heading and for this a separate auxiliary fan was installed and supplied with current from a separate circuit.

Those killed were:

  • E. Bond aged 47 years, labourer,
  • L. Davies aged 37 years, fitter,
  • T. Jones aged 57 years, collier,
  • W.J. Maull aged 61 years, collier,
  • D.J. Price aged 51 years, collier,
  • L.R. Price aged 27 years, collier,
  • W. Smith aged 39 years, deputy,
  • K. Strong aged 32 years, deputy,
  • D. Williams aged 37 years, fitter.

Those injured:

  • L.W. Boulton aged 52 years, collier,
  • E. Davies aged 58 years, transfer point attendant.,
  • J. Jones aged 52 years transfer point attendant,
  • A. Lewis aged 52 years ventilation official,
  • A. Lewis aged 47 years roadsman,
  • T. Lewis aged 56 years transfer point attendant.,
  • R. Morgan aged 26 years, repairer,
  • M.A. Pearce aged 20 years, apprentice electrician,
  • W. Strong aged 55 years, chargeman.

The inquest into the deaths of the men was held by M.r T Alwyn John, H.M. Coroner for North Glamorgan on 11th. May 1962. The jury returned the following verdict:

All nine had died as result on multiple injuries accidentally received in an explosion in the MC3 road at Tower Colliery.

The Report into the causes of and the circumstances attending the explosion at the colliery was conducted by C. Leigh, H.M. Divisional Inspector of Mines and Quarries and presented to The Right Honourable Richard Wood. M.P., Minister of Power in November 1962.

The explosion area was carefully examined after the disaster by all interested parties and the effects of the explosion were found to have been confined to the MC3 heading and a short length of the return level outbye of the junction with the heading. There was little evidence of flame and violence was apparent only at the junction with the return level and immediately outbye of that junction. The explosion was of gas only and coal dust played no part.

Little gas had been found in the mine prior to the explosion but on the day before the explosion tests showed that there had been an increase. The heading had been unventilated for about 90 minutes when the power had been cut off and the auxiliary fan stopped and gas could the have built up. This was confirmed by tests a few days after the explosion.

At the time of the explosion, there were no persons in the heading and no operations going other except power was being restored. The means of ignition was from a severe short circuit which had blown a hole through the cable a loop formed by a bend in the cable. Further investigations discounted any other means of ignition.

The Inspector, Mr. C. Leigh concluded that:

I conclude that the explosion resulted from the ignition of inflammable gas in MC3 heading. The igniting source was arching resulting from a short circuit to earth in a newly inserted length of cable serving the electrical equipment in the heading, and occurred on the inside of a loop in the cable where it had been bent back on itself in order to connect it up to the switch in the heading. I think it highly likely that the short circuit was directly due to the insulation of the cable having been weakened as a result of the acute bending to which it had been subjected in making the connection to the switch.

At the conclusion of the inquiry, the Inspector recommended that:

1).   In any system of working requiring the use of an auxiliary fan provision shall be made so that the power supply to the fan may be maintained while any or all of the other plant in that working is shut down.

2).   In any system of working requiring the use of an auxiliary fan arrangements should be made whereby the supply of electricity is automatically cut off from all electrical apparatus in that working place whenever the auxiliary fan is stopped.

3).   In rapidly advancing headings where short lengths of cable have to be inserted frequently, pliable wire armoured cable or P.V.C. insulated cable should be used. Cable should always be transported in such a manner as to ensure that it is no damaged.

 

REFERENCES
The report of the causes and the circumstances attending the explosion which occurred at the Tower Colliery, Glamorganshire, on the 12th April 1962 by C. Leigh, H.M. Divisional Inspector of Mines and Quarries.

Information supplied by Ian Winstanley and the Coal Mining History Resource Centre.

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