It may be neither of these reasons of course - but two reasons I can think of. On whole-room emergency buttons to cut power to all machinery it might be desirable not to cut the power to all sockets as well - or that machinery might over time end up plugged into non- isolatable sockets. Secondly - machinery must come to a stop in 10 seconds these days, and often depends on electrical braking to do this
- so pulling the plug won't do it - you have to hit the machine stop button.
That may be the cost of adding electrical braking to the machine.
Hi My wife works in the DT dept (metal work / wood work etc) of a local secondary school. She told me that on their latest safety insepction, the inspector said that the electric tools/machines would need their mains connections made via a hardwired switch instead of the 13A plug they currently have. Why is this? I can't see any difference in safety.
They were also told (by the inspection company) that to bring a band saw up to current safety standards, they'd need to fit a key switch and a floor mounted isolation button. The cost of doing this would be £395! Surely there is a less expensive way.
£395 sounds like reasonably good value to be honest.
BS4163:2007 applies
"Health and safety for design and technology in schools and similar establishments ? Code of practice."
Your wife's school should have a copy of this standard. As it is in the form of a code of practice, it is easy to read and fairly accessible to the layman, although you will have to look up some technical stuff if you want to fully understand it.
I am not directly involved in schools, so I'm not familiar with policy/processes but this doc seems to give a useful starting point:
On Thu, 6 May 2010 11:08:44 +0100 someone who may be "Grumps" wrote this:-
They have non-portable machinery which is not permanently connected to the electrical system? Which clown bought and installed the machinery? Perhaps a teacher? Why has this not been spotted before and corrected? Is this an example of the perils of letting schools manage more and more themselves?
Portable tools and the like are... portable and so are plugged into sockets. It is clearly not possible to wire a portable tool into the electrical system permanently. However, they should be equipped with industrial plugs, which go into industrial sockets . I am surprised that a workshop is not equipped with these. 13A plugs and sockets are not intended for use in workshops, they are intended for use in houses, offices and the like. In controlled circumstances, under the supervision of a suitably qualified electrical engineer, they may be provided in workshops for light use, but it sounds like this is not an example of controlled circumstances.
The only grey area is semi-portable items. Not much wood/metalworking machinery comes into this area. It is likely that say a lathe will remain in one position for a considerable time and so can be wired in permanently. If there are any truly semi-portable items, which will be moved around from time to time, then these are usually connected via an industrial plug and socket. An example is
Inspectors don't "say" anything. They give a written report, and it's itemised by machine. If you're expecting a bunch of amateurs (for that's what we are in this context) to hatchet-job a professional, then it needs to be done in the appropriate detail.
Your LEA may (and certainly some LEAs do) publish guidelines for good practice here, which you ought to know about and will probably follow.
There is no need for a one-size-fits-all policy. Each type of machine has its own hazards, they need to be asessed and recorded appropriately. Some classes of machine have similar grouped hazards, but a particular machine might need specific work to meet standards, different to other machines of the same class (the PUWER braking problem).
As PUWER 98 was 12 years ago, all machinery in a school or commercial workshop was already required to be modified to comply some years ago (of course not all has been). You might wish to familiarise yourself with the rules here (HSE has an excellent website full of good practical workshop guides). Particularly relevant are the rules for "spin down time". These can be tough to meet on existing machines. Some will need an expensive retrofit that adds an electrically braked motor and control gear, others can't be braked adequately at all. Often selling an old machine and buying a new one is indeed the simplest approach.
Why did the inspector say(sic) it was needed? Otherwise it's just a cargo cult. Also did the inspector say "should" or "must"?
It _may_ of course be required. There are wiring practice rules, on account of current loading (either sockets or circuits). There are also requirements for machinery control gear. If you're reliant on electrical brakes to meet the spin-down time constraints, you want to avoid cutting the power dead, as that leaves it free-spinning. This is often a problem for schools, who often had widespread E-stops that cut the power to a whole room.
There are also options involving radial circuits to round blue sockets, which is usually a better deal for sheer robustness than "domestic" plugs. Still not requiring hard wiring though.
I'm amazed it didn't have one to start with. Schools often use Startrite machinery, a UK firm that have carved a nice niche for themselves by supplying "schools ready" kit that's already fitted with guards & switches that meet most LEA standards. Also a pricetag that looks "well upholstered" for comparable machinery, if not downright padded! There's also a considerable FUD factor in some of these attachments.
My machines (home workshop, not currently commercial) all have lockable isolators, NVR switches and generally a foot or knee- activated E-stop paddle as appropriate. I regard anything less than this as a bit skanky to be honest, even for DIY use. Note though that a lockable isolator (using loose padlocks) is generally considered sufficient (and a lot more reliable) than a keyswitch. Is the default to be "On" with lockouts for maintenance, or must it really be "Off, unless you're the keyholder" ?
Of course.
Take a look at Axminster for quick switchgear examples on machines. Look at MK Commando (and many others) for switchgear.
If you're dealing with electrical brakes, then 400 quid might be what it costs. But that's only true when it's a braked motor, and when you're retrofitting this as a new motor with brakes where there wasn't one before. If it's unbraked (i.e. you're just triggering an NVR switch) or even if the motor was already braked, it will cost a mere fraction of that.
Why is this a problem? Which specific regulation is it in breach of?
There are cases where you might wish (for good practice) to permanently wire non-portable machinry. It's a reasonable argument that _anything_ in a school needs to be in steel conduit, proof against biting, chewing and window licking. But there's no blanket regulation that says "If our inspector ever finds a BS1363 plug, we get to charge you =A3400 to "fix" it", a situation that is horribly common in the pocket-lining world of "think of the children" safety.
There are issues about not hanging multi-hp motors off ring mains, but that's different. There are times when a 13A rated pin socket just isn't up to the job, no matter what the rating plate says (much of that's about who made the socket, not what's written on it). Big tough plugs beat flimsy plugs every time - so long as you also address the fusing issues.
But there's not, for any regulation I can think of, a simple blanket that rules out BS1363 plugs for machinery in schools.
Having spent many years in various electronics labs and workshops and productions lines, BS1362 plus are almost exclusively and universally used.
Depends... my table saw is semi portable - I could not lift it, but it is mounted on a wheeled dolly so I can shift it around as appropriate to make the best use of space in a small workshop.
On Thu, 6 May 2010 07:29:33 -0700 (PDT) someone who may be Andy Dingley wrote this:-
I never claimed that there was.
What the "electric tools/machines" are precisely has not been defined. However, let's say that one is a small pillar drill,
for example.
Were this installed in a small home workshop, used by one person for hobby type work, then I would say that plugging it into a (metalclad) 13A socket, via a rubber or a suitably resilient plastic plug, is be acceptable, assuming the cable and the wiring to the socket was suitable.
However, the DT dept (metal work / wood work etc) of a local secondary school is a very different environment. In that situation I would expect to see the same machine wired from an isolator, via flexible steel conduit, proof against biting, chewing and window licking.
Wiring systems must be selected, erected and maintained to meet the expected conditions. One adult lovingly doing something is a very different situation to 20-30 teenagers, not all of whom wish to be there.
Quite possibly teachers bought such machines from Screwfix or B&Q and didn't have the knowledge to understand that in a workshop they should be wired up "as it is done in a factory". Quite possibly the teachers have not seen a factory.
By the way, I generally agree with you about the pocket-lining world of "think of the children" safety. However, given the limited information that has been provided, I think that in this case "the inspector" was right. The school are lucky that their poor electrical installation has not caused someone to be killed or injured. They should rectify the defects rapidly rather than complain about the cost of doing what they should have done in the first place. Ignorance is no excuse.
OK, Since there's been a few comments based on general opinion without reference to the appropriate code of practice, here are some extracts from BS4163-2007 for your consideration. The document runs to 142 pages and covers metalworking, woodworking, food preparation, jewellery making, car maintenance, welding, textiles, laser cutters and 3D rapid prototyping, soldering and risks associated with materials (such as hazardous MDF dust). The following represents the salient point relating to electrical installations and the use of fixed and portable equipment. Some sample risk analyses are included at the end.
Note: Notes and references to other publications in the British Standard text are in italics, but have been rendered in plain text here.
5.2 Electrical installations
5.2.1 General =============
NOTE 1 New fixed installations and alterations should conform to BS 7671. Attention is drawn to the Electricity at Work Regulations 1989.
Socket-outlets should be supplied through a non-time delayed residual current device with a rated residual operating current not exceeding 30 mA (In) and an operating time not exceeding 40 ms at a residual current of 5In as specified in BS 7288, BS EN 61008-1 or BS EN 61009-1.
NOTE 2 [snipped reference to Electricty at Work Regs and periodic testing].
NOTE 3 The frequency of inspections and tests of portable equipment depends on the design and use of the equipment (see HSE Guidance Book HSG 107).
Electrical equipment should only be used in the intended environment. [Snipped reference to computer suites and excessive earth leakage] [Snipped reference to detrimental environmental influence and IP ratings]
All portable electrical equipment should be correctly fused.
5.2.4 Main work area switchgear ===============================
The electrical supply to work areas should conform to BS 7671. In each workshop area it should be possible to disconnect and isolate all electrical circuits that supply fixed equipment and socket-outlets by a single switch conforming to BS EN 60669-2-4 or BS EN 60947-3. The switch-disconnector should be readily accessible, clearly labelled ?main switch?, and lockable in the ?off? position. The switching device should not control lighting, space heating and specific socket-outlet circuits for cleaning purposes. Workshop areas without electrically operated fixed equipment and only a 230 V a.c. supply should be fitted with a switch-disconnector and an emergency switch-off system (see 5.2.5) if there is rotating or other machinery (but not portable machinery) present.
5.2.5 Work area emergency switching systems ===========================================
NOTE Attention is drawn to the Provision and Use of Work Equipment Regulations 1998.
Emergency switching systems should be provided in each separate student work area. Preparation areas for staff use only need not have any emergency switching system and should not be affected by the emergency system of any other area. The systems should switch off all circuits supplied via the switch-disconnector in an emergency. Critical circuits specifically installed to remove hazards (e.g. fume extractor fans, lighting, alarm circuits) should not be controlled by the emergency system.
The emergency switching device should be a remotely operated contactor or circuit breaker that opens when the coil is de-energized. The switching device should be controlled by a series of readily accessible push buttons evenly distributed around the work area, at an approximate height of 1.5 m, and clear of benches and machines. It should only be possible to reset the remotely operated contactor or circuit breaker by a single key-operated spring return switch sited within view of the work area it controls. A responsible person should retain the key. (See also BS EN 60204-1, BS 7671 and BS EN ISO 13850.) Push buttons should be conspicuous, and coloured red on a yellow mounting surface (see BS EN ISO 13850) and a safe condition sign conforming to BS 5499-5 should be in place adjacent to each switch.
The emergency stop system installed in a workshop should not negate any other safety systems fitted to machines, e.g. braking systems on hand fed wood cutting machines.
5.2.6 Electrical equipment for fixed machine tools ==================================================
NOTE 1 The Provision and Use of Work Equipment Regulations 1998 (PUWER) require that, where appropriate, stop, emergency stop and emergency isolation systems should be installed for each item of work equipment.
Electrical equipment for fixed machine tools should conform to BS EN 60204-1.
Motor starters, switches and controls for fixed machine tools should conform to, and should be fitted in accordance with, BS EN 60204-1 and BS 7671. They should be readily accessible to the operator from the normal operating position and should not require the operator to reach over any moving parts of the machine. Emergency stop switches (which could be the normal ?off? switch) should be provided at all fixed machines, and easily actuated by the user.
Equipment should be supplied via a fused switch-disconnector conforming to BS EN 60947-3, or a connection unit conforming to BS 1363-4, or a circuit breaker conforming to BS EN 60898, or a residual current operated circuit-breaker (RCBO) conforming to BS EN 61009-1.
Any controls or means of isolation not incorporated in the equipment should be not more than 2 m away from the equipment and positioned so that they can be operated safely while the equipment is in use. Each switching device should be clearly marked with its function and its associated machine/equipment.
Electric motors with a rating exceeding 0.37 kW (0.5 h.p.) should be provided with control equipment incorporating a means of protection against overcurrent in the motor.
NOTE 2 This recommendation does not apply to motors incorporated in current-using equipment conforming to a British Standard.
Means to prevent automatic restarting of an electric motor after certain types of stoppage (e.g. supply failure or voltage reduction) should be provided.
NOTE 3 This recommendation does not apply to automatic control devices that are set to start motors at some interval, and where other safety precautions are taken against unexpected restarting.
5.2.8 Electrical supplies for portable equipment ==================================================
Cordless, battery-operated portable tools should be used if possible. Mains-powered portable equipment (indoors or outdoors) should be supplied via a socket-outlet protected by a residual current device (RCD) (see 5.2.1). The effectiveness of these devices should be verified frequently, using the test button, in accordance with the manufacturer?s instructions.
NOTE Separated extra-low voltage (SELV) supplies incorporating a 110 V centre tapped transformer minimize the risk of serious electric shock. These systems provide a high level of protection in conditions such as in construction sites and heavy engineering workshops. The conditions in school and educational establishment workshops do not generally require this level of protection.
5.2.9 Socket-outlets for portable equipment ===========================================
Socket-outlets of supplies with different voltages should not be compatible with outlets of other voltage systems.
For standard nominal 230 V a.c. supply with neutral at, or approximately at, earth potential, the socket-outlets should conform to BS 1363-2.
Equipment that requires installation in a particular location or that requires an industrial type plug, should be supplied by socket-outlets conforming to BS EN 60309-2, colour coded blue.
For reduced low voltage, if used, socket-outlets should conform to BS EN 60309-2 and should be colour coded yellow.
Equipment that requires an electrical supply greater than 16 A and/or 250 V should be directly connected to fixed wiring.
Socket-outlets for use by caretaking employees only should conform to BS 1363-2. These socket-outlets should be protected by a residual current device and should be sited adjacent to an entrance door if possible. If it is essential to locate socket-outlets for caretaking employees in work areas, they should be supplied from an independent circuit (also protected by a residual current device), labelled ?Cleaning use only? and activated by a removable key.
In new installations, surface mounted boxes for electrical accessories should not have multiple conduit knockouts. For socket-outlets or plugs, consideration should be given to fitting fixing screws that require a special tool for insertion and removal.
Socket-outlets with neon indicators should only be used to supply equipment for which an indication of an ?on? condition is required (e.g. a refrigerator). Neon indicators should not be used to indicate that a socket-outlet is ?off?. Socket-outlets that supply voltages greater than extra-low voltage and up to 250 V (a.c. or d.c.) and that do not conform to BS 1363-2, BS 7288, BS EN 60309-2 or BS 546 (shuttered) should conform to BS 5733.
5.2.10 Plugs for portable equipment ===================================
Plugs for portable equipment should either conform to BS 1363-1 (i.e. should have sleeved pins) and should be fused either in accordance with the equipment manufacturer?s instructions or in accordance with BS EN
60309-2, or conform to BS 546 (fused) or conform to BS 5733.
It is essential that plugs and socket-outlets used outdoors are provided with a degree of protection conforming to at least IP44 in accordance with BS EN 60529, or else conform to BS EN 60309-2.
NOTE In hose/wash-down areas a higher degree of protection might be required and the manufacturer?s advice should be sought.
Only persons with sufficient technical knowledge and practical skills should fit plugs, to ensure that the manufacturer?s instructions are carried out.
9 Portable tools and equipment used in workshops ================================================
9.1 General ===========
1.1 Hazards ===========
Employees and students should be aware of the following hazards: a) electric shock; b) cutters, blades, abrasive wheels and sanding discs, contact with which can cause injuries; c) broken cutters, blades and abrasive wheels, and particles from cutting operations, which can be violently ejected; d) trailing cables and compressed air lines, which could be tripped over; e) contact with the open end of a compressed air line, which can force air through the skin into the bloodstream; f) unrestrained compressed air lines, which can lash about with force; g) inadvertent operation of portable tools; h) dust, which can be inhaled; i) noise; j) batteries, which can spontaneously combust or explode if incorrectly used; k) start-up torque.
1.2 Risk control measures ========================= Portable tools should be single-purpose and robust. Portable tools should only be used for the design purpose in accordance with the manufacturer?s recommendations. Tools should conform to the appropriate standard.
Students should be aware of hazards associated with portable tools and precautions that should be taken during use. Before using the equipment, students should be trained and assessed as competent, and a record of their competence should be kept.
Students should be physically capable of using portable tools, and supervised at all times by a trained, competent person. Personal protective equipment should be used.
Portable tools should be immobilized when changing cutters, blades, etc.
If the machine has moving parts or is likely to produce hazardous material, long hair and loose clothing should be secured. Dangling jewellery should be removed. Gloves should not be worn. Suitable eye protection should be used.
A risk assessment on dust should be carried out, and local exhaust ventilation or respiratory protective equipment provided if required.
A risk assessment on noise levels should be carried out. Ear protection should be provided if required.
Portable tools should be securely and appropriately stored when not in use. Portable tools and supply leads or hoses should be visually examined before use.
A competent person should carry out inspections and tests (as appropriate) at least every 12 months and records of inspections and test results should be kept.
9.1.4 Risk control measures specific to portable electric tools and =================================================================== equipment =========
Portable electric tools should be single-purpose and robust.
Portable electric tools should conform to BS 2769. Attachments should not be used.
Only double insulated mains fed portable electric tools should be used.
A residual current device (RCD) should protect mains sockets (see 5.2.1).
Portable electric tools should be fitted with the correct plug to match the socket outlet and correctly fused.
It is essential that adapters are not used.
The length of supply leads should be kept to a minimum to avoid tripping or accidental disconnection.
Battery powered portable electric tools should be used if possible.
Batteries should be charged, fitted and disposed of in accordance with the manufacturer?s instructions.
Soldering irons and handlamps of extra-low voltage (below 50 V a.c.) type should be used if practicable.
9.2 Portable drills ===================
9.2.1 Hazards Employees and students should be aware of the following hazards: a) long hair, loose clothing, etc., which can become entangled in moving parts of the drill; b) chuck keys, broken drill bits, swarf, work pieces, etc., which can be violently ejected; c) sharp edges on drill bits, work pieces and swarf, which can cause cuts; d) electric shock; e) leads and hoses, which could be tripped over; f) drill jamming, which can produce a torque reaction; g) dust, which can be inhaled; h) ejected particles.
10.2 Mortising machines (hollow chisel type) ============================================ NOTE Chain mortisers are not suitable for school use. Hazards Employees and students should be aware of the following hazards. a) Work pieces in the mortising machine can become loose and can be ejected. b) Hands or clothing can become entangled with the cutting tool. c) Inadvertent starting of the machine can present a hazard. d) Wood dust can be inhaled. Risk control measures It is essential that the mortising machine is provided with: ? a means of electrical isolation using a fused switch-disconnector on or adjacent to the machine, and that it is controlled by a starter incorporating overload protection and no-volt release; ? a conveniently positioned, mushroom-headed stop button or other suitable control device that can quickly stop the machine in an emergency; ? fixed guards (removable only with the use of a tool), or alternatively interlocked guards that enclose the drive mechanisms. A risk assessment should be carried out to evaluate the risks to health from inhalation of wood dust and any action required to prevent or control the risks (see 10.1). Care should be taken to ensure that the timber work piece is securely clamped. The key for locking the bit in the chuck should be removed before starting the machine and after the work is completed. The machine should be included in a planned maintenance programme that should include electrical safety tests.
10.3 Moulding machines (spindle moulders) [Snip]
10.4 Planing and thicknessing machines [Snip]
10.5 Sanding machines (belt, bobbin and disc types) [Snip]
10.5.2 Disc sanding machines [Snip]
10.6 Sawing machines (band, circular and reciprocating saws) [Snip]
10.6.3 Powered fret sawing machines [Snip]
10.6.3 Powered fret sawing machines [Snip]
10.6.5 Vertical panel circular sawing machines [Snip]
10.7 Wood turning lathes [Snip]
Thanks from me too Dave. My wife's dept has the BS4163-2007 doc in pdf format. I'm not going to read it all. But as John says, there doesn't seem to be anything specific that precludes the use of 'normal' plugs/sockets. And there also doesn't seem to be a requirement for a foot operated safety switch, only one that is easily accessible.
Probably showing my lack of knowledge, but how does electrical braking work when power is removed say by pressing the master cut-off switch?
Motor braking these days is generally done by a VFD (variable frequency drive) inverter and a three-phase motor. It costs money, but it gives the advantage of running three-phase induction motors from single-phase supplies and also variable speed. A cruder system (even though they're so over-priced that they cost nearly as much) is DC injection braking - a system developed for 1900 trams. It's not a good fit to woodworking equipment, as it has a tendency to shock-load machines, snapping bandsaw blades and causing table saw spindle nuts to loosen. For either of these, a loss of power means a los of braking.
Mechanical brakes were used on older (pre PUWER) woodworking machinery where there was a recognised need for a brake. These use a solenoid to disengage a mechanical brake (often a solidly locking clutch onto a viscous damper, rather than a controllable brake). Never common, almost unknown for the post-98 retrofits, they do have the advantage that dumping the power does also apply the brakes.
I once had a H&SE inspector tell me that a 1.5 tonne lathe was a portable appliance, and therefore needed PAT, because it was connected by a three phase plug and socket.
On Thu, 06 May 2010 23:27:51 +0100 someone who may be Grimly Curmudgeon wrote this:-
Indeed, it demonstrates that what I typed was correct.
"5.2.6 Electrical equipment for fixed machine tools"
"Equipment should be supplied via a fused switch-disconnector conforming to BS EN 60947-3, or a connection unit conforming to BS
1363-4, or a circuit breaker conforming to BS EN 60898, or a residual current operated circuit-breaker (RCBO) conforming to BS EN
61009-1."
No mention of a plug and socket. As I have said before the precise nature of the machines has not been explained, so we don't know whether any of them are fixed, or whether they are all portable.
"5.2.9 Socket-outlets for portable equipment"
"For standard nominal 230 V a.c. supply with neutral at, or approximately at, earth potential, the socket-outlets should conform to BS 1363-2."
Indeed, but you neglected the following sentence, which is:
"Equipment that requires installation in a particular location or that requires an industrial type plug, should be supplied by socket-outlets conforming to BS EN 60309-2, colour coded blue."
It then goes on to say, in effect, that 13A sockets should be carefully controlled:
"Socket-outlets for use by caretaking employees only should conform to BS 1363-2. These socket-outlets should be protected by a residual current device and should be sited adjacent to an entrance door if possible. If it is essential to locate socket-outlets for caretaking employees in work areas, they should be supplied from an independent circuit (also protected by a residual current device), labelled ?Cleaning use only? and activated by a removable key."
All of which demonstrates that what I typed was correct.
He didn't quote the bits about wiring systems being suitable for the environment the wiring is installed in. I have no need to quote them, but they are there. The Wiring Regulations are not a "Noddy Guide", written in a way where everything for a particular circumstance is on one place [1]. One needs to look at several sections to understand what they ask for in a particular circumstance.
Nice try, but anyone who cares to look can read what I typed and see for themselves that what you have claimed I typed is a lie.
What I typed was, "13A plugs and sockets are not intended for use in workshops, they are intended for use in houses, offices and the like. In controlled circumstances, under the supervision of a suitably qualified electrical engineer, they may be provided in workshops for light use, but it sounds like this is not an example of controlled circumstances."
If the best you can do is invent what others typed and then attack that invention then perhaps it is time for you to give up with as much grace as you can muster.
The original poster appears to have come to the group with an agenda of silly company gold-plating requirements in order to rip off the school. Little information has been provided on the nature of the "tools/machines", but from what little information has been provided it seems to me that the company have not tried to rip off the school.
I have not covered the saw, others have done that far better than I could.
Schools/LA's don't allow these in areas where children have access, because they aren't shuttered. The place where this most often comes up are dimmer packs for stage lighting, where their use is otherwise pretty universal.
PAT testing applies to fixed and stationary appliances too. Think of the "Portable" referring to the tester, not the appliance. An important part of the test is assessing the appliance in use where it's normally used, and not having the appliances brought to a testing location, so it's the tester which needs to be portable, not the appliance. An example is that a hot air paint stripper with nothing wrong with it would fail a PAT test if it's use was as a hand drier by a wash basin, whereas that failure could not be detected if the appliance was moved away from its normal use to some different testing location.
The word "portable" doesn't appear anywhere in the correct name of the procedure. So he was right that your lathe should be part of your PAT procedure, but his reason was wrong.
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