PRINCIPLES OF
ELECTRICITY
• Over all Lab electrical system
• Lab electrical equipment
Installation
Laboratory equipment Safety
• Electric Shock And Personal Safety Personal Safety Guidelines
First Aid
List of common equipment
OVER ALL LAB ELECTRICAL SYSTEM
- Dual sockets must be installed, 110v to support American system and 240v for the British system. The sockets must be clearly labeled preferably with different ink colors.
- Dual 50/60 Hz cycles must be available. 110v equipment works on both cycles however 240v definitely requires 60 Hz.
- Both types of sockets should be available on all of the bench tops.
- At least three sets of sockets should be available on each wall of the laboratory.
- 240v sockets and sometimes for extra safety 110V sockets must be earthed.
- 110v sockets must be either two pins round or flat face sockets and all 240v should be universal three pin flat face sockets.
- Stabilizers must be connected to continuously running equipment in order to stabilize any electrical fluctuations
- The main electric connection should be linked to a back-up generator as a compensatory mechanism in case of complete electrical failure.
- The fuse box should support the required electrical consumption of the equipment in the lab. In case this consumption exceeds the fuse capacity the fuse box must be changed.
- The laboratory must have a circuit breaker Fuses as circuit breakers prevent over-heating of wires and components that might otherwise create fire hazards. They disconnect the circuit when it becomes overloaded.
LAB ELECTRICAL EQUIPMENT
This is the most valuable item in the medical laboratory. Coulter Counter or Cell-Dyn may cost as much as $200,000 or a full Chemistry auto- modular may cost up to $300,000. Therefore their initial installation should be carried out very carefully.
Other electrically powered equipment, such as hot plates, stirrers, vacuum pumps, electrophoresis apparatus, lasers, heating mantles, ultrasonicators, power supplies, and microwave ovens are also essential elements of many medical laboratories. If not handled carefully or not maintained, these can be damaged or can be hazardous to lab personnel particularly because they use large capacitors and high voltage .
Installation:
- Dual voltage equipment should be preferred and this should be pre-adjusted to 240v.
- Initially ask the dealer to install the equipment
- Manual must be read carefully, and manufacturer’s guarantee must be clearly documented and placed in safe place.
- Make sure the equipment is Switched-off before plugging in.
- Check plugs and use adapters accordingly.
- Extension wires should never be used on heavy duty equipment.
- Light equipment such as centrifuges, incubator or water baths can be plugged to extension wire however maximum 20Amp fuse and minimum 10 Amp fuse is recommended in the plug.
- Much bigger fuse gauge e.g. 30 Amp allows high current to pass through un-noticed subsequently damaging the equipment.
Too little fuse gauge <10 Amp will not tolerate even a minor
surge, which may be acceptable for the equipment but will burn the fuse.
- There shouldn't be any loose contacts that may cause continuous low grade sparking over the long term leading to over heating of plug.
- After "switching on" allow warming up for at least 30seconds - Allow at least 5 minutes cooling after switching ‘off’ before
switching ‘on’ again.
Laboratory equipment safety:
- If the voltage is not clearly indicated (in case of missing manual), remember, install the equipment in 110v first.
- Make sure there are no exposed wires in the apparatus.
- Don’t obstruct vents, which allow the release of warm air.
- Long term 'switched-off' equipment should be unplugged.
- Make sure electrical cords do not dangle over bench tops or trail on the floor.
- don't "piggy-back" double adaptors or stack plugs on top of each other as this may overload the power point and cause a fire
ELECTRIC SHOCK AND PERSONAL SAFETY
Electric shock and fire are the main hazards of electricity. Electrical shock occurs when the body becomes part of the electric circuit when an individual comes in contact with both wires of an electrical circuit.
The severity and effects of an electrical shock depend on a number of factors:
1- The pathway through the body, 2- Amount of current,
3- Length of time of the exposure,
4- Is the skin wet or dry because water is a great conductor
of electricity, allowing current to flow more easily in wet conditions and through wet skin.
The effect of the shock may range from a slight tingle to severe burns to cardiac arrest.
Current Reaction
1 Milliampere Perception level
5 Milliamperes Slight shock felt; not painful but disturbing 6-30 Milliamperes Painful shock; "let-go" range
50-150 Milliamperes Extreme pain, respiratory arrest, severe muscular contraction
1000-4,300 Milliamperes Ventricular fibrillation
10,000+ Milliamperes Cardiac arrest, severe burns and probable death The chart above shows the general relationship between the degree of injury and
amount of current for one second's duration of shock.
In addition to the electrical shock hazards, sparks from electrical equipment can serve as an ignition source for flammable or explosive vapors or combustible materials.
Personal Safety can be secured if following guidelines are followed:
- Rubber shoes and gloves should be worn before handling electrical appliances particularly exposed wires.
- Water vapors or any other fluids must be wiped well before handling the electrical components of the appliance.
- Work under sufficient light to avoid getting in direct contact with high voltage components.
- Never expose +ve and –ve wires at the same time, always keep one covered to avoid coming in contact. This can lead to short- circuiting and a mega electrical jolt.
- Handle 240v equipment with extra care, particularly when switching ‘on’ these machines after extensive repairs.
- Never try to insert scissors or safety pins in the sockets to remove obstruction.
- Know the location and how to operate shut-off switches and/or circuit breaker panels. Use these devices to shut off equipment in the event of a fire or electrocution.
- Limit the use of extension cords. Use only for temporary operations and then only for short periods of time. In all other cases, request installation of a new electrical outlet.
First Aid:
• Ring emergency number for help which should be posted on the wall clearly
• Turn off the power source
• Do not touch the person with your hands or any metal or moist objects while the power is still on
• If you are unable to turn off the power, push the person away from the power source using a broom handle, dry stick or other non- conducting object.
• If the person is unconscious, not breathing, or has no heart beat, start resuscitation and continue until an ambulance arrives.
Most Medical Laboratories contain following equipment:
A. Refrigerators and Freezers B. Stirring and Mixing Devices C. Heating Devices
C.1 Dry ovens and microwaves C.2 Hot Plates
C.3 Heating Mantles C.4 Water Baths
C.5 Hot Air Baths and Tube Furnaces
D. Centrifuges
E. Rotary Evaporators F. Autoclaves
G. Electrophoresis Devices H. Spin vacuums
I. Analyzers
J. Documentation systems K. Computer devices
IN CLASS ASSIGNMENT GROUP A
You have been assigned a task in Medical Laboratory to check electrical appliances as routine annual exercise. What safety pre-cautions will you take?
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IN CLASS ASSIGNMENT GROUP B
Your colleague a Medical Technologist received a severe electric shock while switching 'on' a recently repaired heavy duty equipment.
Sequentially describe the steps you will take to handle her.
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IN CLASS ASSIGNMENT GROUP C
You want to equip your laboratory with: a dry oven (800W), a complete Chemistry auto-analyzer (1600W), a CBC auto analyzer (1000W) and other smaller equipment totaling (1800W). What should be the capacity of your fuse box be?
If one fuse can take up to 2000 W load; how many fuses will you need in the fuse box? How will you distribute the electric load of above
mentioned equipment on the fuses?
An over night power failure in a laboratory will affect all of the following except;
a- fridge’s with stabilizers plugged to regular sockets b- analyzers which are rarely used but remain switched on
c- auto-analyzers without stabilizers plugged in emergency sockets d- both a and c
IN CLASS ASSIGNMENT GROUP D
You have been hired by a Medical company that wants you to design the electrical system of a Medical Laboratory. Mention at least eight main points you will take into consideration?
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IN CLASS ASSIGNMENT GROUP E The severity of an electric shock depends upon following factors:
Factor Reason
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4-
A human body can survive an electric shock of up to:
a- 50-150 milliamperes b- 1000-4300 milliamperes c- 1000-4300 amperes d- None of the above
Which one of the following steps must be carried out to ensure safe installation of electrical equipment in the lab that doesn’t clearly indicate the voltage on it;
a- provide dual sockets in the laboratory
b- plug the equipment into an earthed 240V socket c- plug the equipment into a 110V socket
d- never use the equipment
IN CLASS ASSIGNMENT GROUP A
You have been assigned a task in Medical Laboratory to check electrical appliances as routine annual exercise. What safety pre-cautions will you take?
IN CLASS ASSIGNMENT GROUP B
Your colleague a Medical Technologist received a severe electric shock while switching 'on' a recently repaired heavy duty equipment.
Sequentially describe the steps you will take to handle her.
IN CLASS ASSIGNMENT GROUP C
You want to equip your laboratory with: a dry oven (800W), a complete Chemistry auto-analyzer (1600W), a CBC auto analyzer (1000W) and other smaller equipment totaling (1800W). What should be the capacity of your fuse box be?
If one fuse can take up to 2000 W load; how many fuses will you need in the fuse box? How will you distribute the electric load of above
mentioned equipment on the fuses?
An over night power failure in a laboratory will affect all of the following except;
a- fridge’s with stabilizers plugged to regular sockets b- analyzers which are rarely used but remain switched on
c- auto-analyzers without stabilizers plugged in emergency sockets d- both a and c
IN CLASS ASSIGNMENT GROUP D
You have been hired by a Medical company that wants you to design the electrical system of a Medical Laboratory. Mention at least eight main points you will take into consideration?
IN CLASS ASSIGNMENT GROUP E The severity of an electric shock depends upon following factors:
Factor Reason
1-
2-
3-
4-
A human body can survive an electric shock of up to:
a- 50-150 milliamperes b- 1000-4300 milliamperes c- 1000-4300 amperes d- None of the above
Which one of the following steps must be carried out to ensure safe installation of electrical equipment in the lab that doesn’t clearly indicate the voltage on it;
a- provide dual sockets in the laboratory
b- plug the equipment into an earthed 240V socket c- plug the equipment into a 110V socket
d- never use the equipment
Internet based assignment;
1- www.google.com
2- Search: electrical safety in medical laboratory
3- "click on" Lab Safety manual
Princeton University Laboratory Safety manual
4- Read Sections: 7.7 Electrical Safety
7.9 Laboratory equipment
11 Anecdotes