http://www.allaboutcircuits.com/vol_1/chpt_3/3.html

This is not brilliant and I've been looking for a web site about kneeling shocks but can no longer find it.

However, It goes through the process of the hows and whys and you might find it interesting.

Zs

UKPN,

You would need your passport for Danbury these days, the neighbouring villages have tightened up the border guards since a well known mouse moved in

Stu

---i like it! best wishes in your new home, and if your supply goes off in
high winds i will make sure the boys (and girls) get round to reinstate you
first.

Regards.

We used to request rubber mats at front of switchboards on electrical reports, don't know if this recommendation is current (No 4 now ) . However, you could use a supplementary page.

Also used to Supply and install electric shock notices. (Industrial & Commercial)To keep from writing this requirement down on report, if one or two was missing at main switchboards.

Memorandum of guidance on the Electricity at Work Regulations 1989
Principle regulation applicable:- 4(4), 14 Mats for covering floor near electrical equipment where direct contact may occur
21
Specification: Rubber mats for electrical purposes BS 921: 1976

Lifts are different, all must have by a rubber mat fitted at front of each control panel, traction and hydraulic.

With modern enclosed switchgear and related equipment there seems little point in rubber mats.
In my experience the practice spreads due to health and safety inspections, done by "inspectors" who have little if any knowledge of such matters.

In my own workplace we have independant "inspections" twice yearly.
They always recomend
More fire extinguishers
More rubber mats
More emergency lights
More first aid kits
More safety signs.

After all, you cant have too much safety can you ?

I have counted the warning signs on the boiler room door
Danger high voltage
Danger 415 volts
Danger 240 volts
Danger 11,000 volts (which is untrue, unless you dig a tunnel into the substation)
Danger 24 volts !
Danger gas installations.
No smoking
Do not use mobile telephones.
Do not use 2 way radio
No smoking
Danger oil, highly flammable (untrue)
Danger, trip hazard
Danger hot surfaces and equipment
Danger, step or change in height
Danger low pipes, hard hat required.
Obtain permit to work
May contain asbestos
Nearest eyeswash station xxxxx
Neaerest first aid kit xxxx
Nearest telephone xxxx
nearest fire alarm call point xxxx

I bet the next safety inspection will recomend another sign, or more rubber mats.

Can you still see the door ?


Stu

i think people tend to switch off with that stupid amount of information and ignore all of it.

Better to concentrate on the essentials, and essentially bar everyone entry other than suitably trained (not muppetts) staff

if its truley that dangerous no one should be going in there!

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Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry


Edited: 11 August 2012 at 09:13 PM by peteTLM

I've found that many clients specify the use of rubber matting in switchrooms.
Whilst I tend to agree with - "Would I trust a rubber mat - never, would I be happy with at least 3 - 5mm of nitrile between me and the damp switchroom floor - every time", - I remain sceptical on their general use.
Is the operation of metal enclosed switchgear too different from touching or standing by a live motor or transformer? No-one suggests putting insulating matting by all electrical equipment.
The matting often has to be lifted when using circuit breaker trolleys.
When matting is subjected to dirty site conditions it's insulating values must be very unreliable. Do operators maintain and test their matting?
I worked for one company that, I think, had a practical approach - there was no matting in the switchrooms but if someone was to work on the equipment with even a remote risk of conductors becoming live then the Authorised Person would lay down a piece of HIS matting whist he ensured that the site was safe and the work was allowed to progress. The matting as left in place for the duration of the work. I can hear people saying - "why? - he shouldn't need it if it's safe" - that takes us back to - "Would I trust a rubber mat - never, would I be happy with at least 3 - 5mm of nitrile between me and the damp switchroom floor - every time".
Regards

Why wouldnt you want rubber matting, try commisioning panels and having to sit on the cold concrete floor to get to the bottom compartment.
Also hides the poor attempt by the workies who install the plantroom steels and flooringthat the panels sit on

It could be, if you are looking at closing a fuse-switch with a metal operating handle onto a possible fault. That said, my risk asessment of the task would still require my insulating gloves, as I consider it a safer option.

Regards,

Alan.

The Americans have a left hand rule for closing switchgear on suites of panels. Nothing to do with Mr. Fleming or rubber mats! Much switchgear with high fault levels is switched remotely from behind blast walls, even when there is a type test certificate, and for good reason.

I don't hang around longer than necessary near power transformers with oil, I've seen the results when a tapchanger tank on a transformer burst open, due to a mechanical fault, and another when a pressure diaphgram operated on a 132kV unit.

Those who cling to a tradition of rubber matting in front of switchgear panels, are hopefully a dying breed.

Regards

Only a little of it !
In my sillier moods, I am tempted to add a notice reading "warning this is an outward opening plant room door and not a noticeboard"

Modern switchgear SHOULD be safe to operate without rubber mats, protective clothing, or other special precautions.

I must admit though that in some circumstances that I take additional precautions including the wearing of linesmans gloves, flame retardant clothing, or the use of a long poking stick to reset large circuit breakers.

If a large circuit breaker is correctly selected for the available fault current and other conditions, then it SHOULD be safe to stand in front of it and press the "set" button.

To stand 3M away, and to turn away from the equipment is less safe than remote operation, but must reduce the risks as compared to standing right in front of it.

My risk assessment says "get someone else to do it"

Stu

Broom handle?

Nope, most that you buy from tescos these days are metallic, no insulating properties at all.

Stu

--"modern sw/gear SHOULD be safe to operate without rubber mats, protective clothing or other special precautions.

almost as bizarre as the topic.

Regards.

My risk assessment usually says send everyone else out of the room, and have a clear route to at least one exit!

It is far safer to find yourself outside and think "why am I out here?" than remain inside and think "bugger" when things have gone slightly wrong!

Regards,

Alan.

The other reason for sending everyone else out of the room is to minimise injuries if it does go wrong, also if you are the one thats injured there will be someone to get you help.
This seems to be fairly common for electricity board trained people but not very common else where. Several times I have been in private substations and when someone is about to operate a switch I step out the door, only to be asked if I am 'frightened' or words to that effect. Once you explain the reasoning though people tend to agree its common sense.

We removed our rubber mats in front of 6.6kV switchgear as they were blocking easy roll-out of the roll-on-floor breaker trolleys. That and also the fact that it was not clear what they actually protected against. Clearly you would never use a rubber mat as the primary protection during live working and would have to use a combination of insulating gloves and insulating footwear anyway.



Don't count on it, despite what the manufacturers say. I wouldn't like to rack in a breaker on a 50kA busbar without a minimum 12 cal/cm2 flash ppe on. Molten copper tends to fly through those flimsy sheet steel doors they make these days. There are arc-proof switchboards to IEC 61641 available but unless it's been type tested to it I'd stick with the ppe on lv switchboards > 30kA.

For HV switchgear PPE is a must even with the doors closed. Read the test criteria for the arc fault test from BS EN 62271-200:

"Deformations are accepted, ...projections of small parts, up to an individual mass of 60g are accepted"

Regards, Tim

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Everyone loves a fireman - but hates the fire inspector.