9: electrical safety

Question 1

Factors effecting electrocution

Answer 1

• Electrical pathway through body
• Susceptibility of body parts
• Current magnitude
• Current type (e.g. continuous, impulses etc.)

Question 2

Body impedance (resistance) based on nature of contact

Answer 2

•	Surface area of contact
•	Pressure exerted
•	Temp
•	For low voltage-
o	Degree of moisture
o	Presence of electrolytes

Question 3

Susceptibility of body parts

Answer 3

• Sensory reactions- electrical impulse stims nervous system
• Muscle reactions- twitch generated
• Thermal reactions- current through body overheats cells- usually and current entry and exit points
• Cardiac reactions- stimulate heart and affect fibrillation
• Electroporation- potential across membranes may be high enough to cause permanent pores to form. Reversible at low, irreversible at high

Question 4

Levels of electrical safety

Answer 4

•	Equipment
o	Class 1 = Protectively earthed
o	Class 2 = Double insulated
•	Procedure
•	Environment

Question 5

Equipment testing

Answer 5

• Visual inspection
• Protective earth resistance
• Insulation resistance
• Touch current
• Earth leakage current
• Patient leakage current- applied part and earth
• Mains contact current