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Posted By Geoff Brock
We have had a curious accident and I should be grateful for views on my hypothesis on its cause.
A member of staff moved a office shredder (well-known, quality brand) which had been in situ for years. He then used it, and there was a small explosion and a sheet of flame shot though the feeder slot, causing minor burns.
On inspection, the bin was distorted from the exlosion and had a layer of very fine black ash in it. The rocker on/off switch had a minor fault which caused it to spark.
Could the movement of the bin have caused a very fine paper powder to be disturbed, and the fautly switch triggered a powder explosion? Should manufacturers warn of the risk?
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Posted By Richard Weir-Ewing
Geoff
Geoff
In the first place it should have been switched off before moving it.
Yes very fine dust could have accumulated around the switch and being faulty could cause the dust to ignite.
Was it PAT tested? Regularly checked and cleaned?
Manufacturers do not recommend leaving the equipment switched on for long periods (I know in or office they are switched each night.) This will only add to the heat/burn of a faulty switch.
Rich
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Posted By Geoff Brock
Thanks, Richard.
To clarify: it was switched off before it was moved. It was PAT tested. Emptied, but not thoroughly cleaned. Switched off at night.
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Posted By Frank Hallett
Hi Geoff, I agree that the most likely cause of the explosion could easily been the dust being disturbed in moving that was then ignited by the potentially defective switch.
I am assuming that this was a "double-insulated" device with no earth continuity lead?
PAT testing should identify defective equipment, but only if there is a loss of insulation resistance, creation of a spark on the live or neutral would probably not be identified; though if it was a breakdown between live & neutral &/or earth a PAT test should have found it.
The shredder motor and blade section is rarely designed or intended to be accessed for repair or maintenance and therefore it is most unlikely that anyone would attempt to give it a thorough clean.
Hope this helps to assist your next move.
Frank Hallett
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Posted By Fred Pratley
I would agree with your thoughts on the fine paper dust aspect.
It sounds possible that the movement disloged paper dust accumulated inside the shredder that was then thrown up when it was restarted.
When you say the rocker on/off switch, is this the microswitch fitted in the feeder slot or an external switch located on top?
If the switch you refer to is next to the feeder slot, it could be the ignition source, or it could have ben simple static.
Good luck with your investigation.
Fred
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Posted By Bill Elliott
A reportable Dangerous Occurence under para 5 of Schedule 2 RIDDOR. I would also inform the manufacturer - they may not thank you for the information but presumably the Fire Service may be taking this up with them too.
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Posted By Geoff Brock
Thanks for your responses, all. I did report it as a RIDDOR accident and wrote to the manufacturers. Nothing from either, despite repeated requests to confirm my unusual hypothesis or tell me I was going daft.
All cables, plugs, etc., checked and no visible defects.
The responses on the site seem to suggest that I am not losing my marbles, and I will now close it off. I will look into a cleaning regime perhaps. But then, how many shredders are there in operation and how many are carefully cleaned to prevent an explosion of this nature? Not, I think, a high priority.
Thanks to all respondents
Geoff Brock
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