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Electrical Safety

Electrical equipment is a significant part of the equipment used in all chemical laboratories. Heating, stirring and centrifugation are examples of common electrically operated equipment. Equipment cannot be designed so that electrical accidents are impossible; but by following a few basic safety rules when connecting and operating equipment, the vast majority of electrical accidents can be avoided. Electrical repairs may only be carried out by trained personnel.

All safety precautions should serve to prevent electric current from passing through a person. The strength of the current going through a person is determined by the transient resistance of the skin. The resistance is significantly reduced and the current strength therefore increases if the skin is wet or damp.

  • Never operate any electrical equipment with wet or damp hands.
  • If liquid is spilled on an electrical appliance, disconnect it before cleaning it.

How dangerous a current is depends on not just the current itself but also on its path in the body. A current of 50 mA passing through the heart region is lethal.

  • Therefore, never operate an electrical appliance while one hand is in contact with a radiator, water pipe or similar grounded object.
  • Do not operate electrical equipment while standing on a damp floor, which may be grounded. If necessary, wear insulating footwear.

When installing or connecting new equipment, make sure:

  • The appliance is grounded. Call a professional.
  • Wires marked yellow/green may only be used as a grounding wire.
  • Multiple appliances in the same set-up must be connected to a common grounding cable.
  • Extension cords must be grounded. It is not permitted to use extension cords from private homes.
  • Do not tinker with electrical appliances yourself. Call a professional.

If an electrical accident has happened, remember:

  • The power supply to a defective appliance must be disconnected before the person involved is touched (if the person is in contact with the appliance).
  • That electric accidents can cause shock and unconsciousness. See First Aid.
  • To fight fire in electrical installations with carbon dioxide extinguishers, never water. Powder extinguishers can be used but will often destroy the equipment.

Approved connectors

Equipment used at the Department of Chemistry must be properly grounded. It is the responsibility of the user's to verify that the equipment is grounded.
The Danish standard is three pins on the plug: Phase, zero and ground. Figure 4 below shows such a connector.

"Schuko"-connectors

Unfortunately, equipment is often supplied with “Schuko” connectors, (see Figure 1) which is the European standard. They do not provide any grounding in a Danish power outlet!
We have several cases of users who have been shocked or have lost measurements due to lack of grounding.

Therefore, remember to:

Check the existing equipment. If you have Schuko connectors, do one of the following:

• Replace the entire cord if it is an interchangeable device cord

• Cut off the Schuko connector and have a Danish plug fitted instead (Figure 4)

• Plug a Schuko adapter into the connector that converts it to Danish plug (Figure 2)

When ordering equipment, remember that the dealer must deliver it with Danish ground plugs.
Adapters, Danish appliance wires and Danish plugs are available at the workshop.

Schuko connectors may only be used at the Department of Chemistry if done so with an adapter that ensures grounding.

"Banana Connectors"

It is forbidden to use "Old-fashioned banana plugs" for appliances or measuring equipment that use or may use voltages above 30 V AC and 60 V DC.
For electronics at voltages below 30 V AC and 60 V DC, the old 4 mm glossy banana plugs are still permitted.
For all other equipment using test leads, other plug types or banana plugs with fixed or sliding protective sheaths must be used to ensure that no contact with live parts is possible.

Computing power

Computer power connectors have flat inclined pins, see figure 5.
They should only be used for computer equipment, not for appliances!
Keeping computer equipment and appliances on separate electrical systems protects computers from overload.

Double-insulated appliances

If an apparatus is marked with the symbol of "double-insulated", a square inside another square (see figure 3), there is no safety requirement for grounding.
This type of apparatus may be provided with "europlug", as shown in Figure 3.

Other types of connectors

There are numerous electrical connections, both for power supply and for connection between appliances.
If in doubt, contact a professional to make sure the connection can:

• supply the correct voltage

• can handle the required current

• have proper grounding

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