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Electrical Safety

Electrical Safety in the laboratories at BI/BMB

Staff and students should not be put in unnecessary danger! We are very strict about electrical safety and it is for your own sake! We urge you to inform the Electronics Workshop whenever you see things that are not up to standard.

If we see machines or workbenches which are unsafe in any way, we will ask the person responsible to fix the problem, and if this does not happen the matter will be sent on to the Safety Representatives.

Everything built and repaired at the Electronics Workshop is safe, in order, and legal. We will not repair any machine that does not meet legal requirements without adjusting it so that it becomes legally compliant.

WE CANNOT COMPROMISE ON SAFETY, whoever had the thing made, however short a time it will be used, or whatever.

Electrical safety must be taken seriously.

Discard equipment which does not meet the safety standards. This is your life and health! 1993 saw the introduction of strict requirements for:

  • Equipment safety, and
  • Users' awareness of safety conditions.

Please read all these instructions carefully so that you are also aware of the rules and are not taken by surprise.

All who use or maintain laboratory equipment have a responsibility for safety and an obligation to ensure that the equipment is in order. If there is there any doubt, do not use the equipment and ask BI / BMB 's technicians to take care of it.

Note that the Danish version of this page contains the rules that will be applied: this English version is intended as an accurate translation but comes without guarantee!

New equipment and BI / BMB 's rules

  • All new equipment must be CE marked (this has been a compulsory requirement since 1997).
  • BUT: the CE marking is unfortunately not an endorsement (as many believe), but only the manufacturer's declaration that the equipment is safe to use. Therefore always check for correct mains plugs and high voltage connectors.

It appears, unfortunately, that you need to evaluate equipment critically even before purchase!

BI / BMB 's Safety Committee and the department leaders produced the following warnings and rules for electricity safety in our laboratories (2004):

  • Banana plugs (patch cables) etc. with exposed electrical parts must be removed immediately!
  • Sockets with spring-loaded covers may not be used
  • High voltage plugs and connectors should be the correct safety connectors with solid covers
  • All electrical laboratory equipment must be earthed via the mains cable, ie. mains plugs must have 3 pins and not 2 pins
  • Contact BI / BMB 's technicians before buying new power supplies and electrophoresis apparatus to ensure that it conforms to BI / BMB' s requirements.

Here are the main points.

General dangers with electrical equipment :

  • Electric shock causes the muscles to contract violently in a kind of seizure. Strong currents can cause burns.
  • The most dangerous electrical accidents result in cardiac arrest, in milder cases you can get a very unpleasant shock.
  • Never touch electrophoresis devices or electrical wires when these are connected to a power source. (Under the right conditions, it should not actually be possible.)
  • Virtually all liquids in laboratories are electrically conductive. Many of them are even very good conducters, corresponding to direct connection with the electrical source.
  • Electrical equipment and wiring should always be dry and clean, without salt deposits. Never work with electrical equipment with wet hands or wet gloves (the thin rubber gloves do not insulate against high voltages).
  • Cold rooms entail an increased risk of electrical faults and accidents due to condensation problems.
  • The two most dangerous power sources are the 230V mains and the even higher voltages found in electrophoresis devices (see later for specific rules).

When in doubt about whether the equipment is properly designed, bear in mind this basic rule:
All equipment must be protected against people accidentally touching the live components in all possible situations!

230 volt AC (mains) supply

The main principle is that all electrical equipment must be earthed through the mains cable. The equipment is thereby much better protected against electrical shock and accident, even when the equipment shorts out.

  • All laboratory equipment shall have a "Danish" 3-pin mains plug with earth: 2 round pins and one flat "earth" pin under them. Mains cables with "German" (2-pin, no earth) plugs look good enough but are not earthed in our Danish sockets. Do not use them: throw them away! The right plugs are available in the electronics workshop.
  • Connectors and cables must be flawless. Users must ensure that the mains cable is in good condition, ie. cable, plug and socket(s) are all undamaged (pins intact, no damage to the insulation, etc).

Also note that:

  • Cables must be of sturdy quality, without splits or discoloured patches from heating plates, etc.
  • Plugs should sit properly in their sockets. Cables should be held in cable clips/holders so that they can't pull.

If there doubts are about the quality, then discard the cable and get a new one!

Ciruit breakers cannot do everything

Note that ciruit breakers only ensure shorting to earth. You get an electric shock before they trip anyway, so are likely to drop whatever you are holding including glass and hazardous liquids. If you touch both live AC wires you can be exposed to several kilowatts - maybe for hours. And ciruit breakers do not protect you from faults in the power supply output voltage.

Electrophoresis apparatus high-voltage connectors

Voltages are often very high. This places great demands on equipment, cables and connectors.

  • The wires should be of best quality - and always with an approved "safety plug".
  • Gel apparatus and wiring shall be insulated (US: isolated) from the 1000 Volt (possibly 1500 Volt) supply, the quality must be optimal.
    • Heat resistant silicone-rubber wires must always be used.
    • Avoid ordinary rubber wires (they crack and split) and soft plastic pipes which melt easily if they touch a hotplate.
  • Never use any type of adaptor, extension cable etc to switch from an approved safety plug to a plug type with lower safety. These plugs are too dangerous and must be completely removed.
  • All wires, leads and gel apparatus must be rated to at least the same voltage as the safety plug.

Safety jacks and connectors of the correct type

In BI / BMB we use only two kinds of safety jack, other connector types may not be used in laboratories. Note that both types have an insulating cover, so the "live" element cannot be touched directly.

  • Normal 4mm safety jacks as are standard for most equipment. They are internationally recognised and are suitable for approx. 1000 volts - when they a re dry.
  • 2 mm safety jacks, with a longer, stronger cover, are suitable up to approx. 1500 volts.

Note: Sockets with spring-loaded covers are unsuitable, they are only for low voltage (in order to minimize unintended short circuits). You may under no circumstances use them! The same applies to old-fashioned "banana plugs" (patch cables and similar connectors and extensions), they should be completely removed, they do not meet the rules and are too dangerous.

Power supply safety

  • Power supplies must of course have the right output sockets which mate with the correct safety jacks :
    • 4mm safety sockets have a milled groove which corresponds precisely to the male jack's cover
    • 2mm safety socket grooves are deeper, corresponding to the longer covers on the 2mm jacks
  • Equipment with old-fashioned jacks for banana plugs should be discarded or modified!
  • High voltage outputs from power supplies must be insulated/isolated "in relation to earth" or have a safety circuit which interrupts the supply by earthing. (This can only be verified by technicians and users must not see this extra security feature as an excuse to relax other requirements.)

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