EFCOG Electrical Safety Task Group ELECTRICAL SAFETY FOR RADIOLOGICAL CONTROL TECHNICIANS EFCOG Electrical Safety Task Group Module 7

EFCOG Electrical Safety Task Group

ELECTRICAL SAFETYFOR RADIOLOGICAL CONTROL

TECHNICIANS


Module 7


ELECTRICAL SAFETY FOR RCT’S

Batteries Stored on shelvesBatteries Stored on shelves

Unprotected with easy accessUnprotected with easy access


Exposed Electrical above bleed valvesExposed Electrical above bleed valves



Shock or Arc Flash Hazard Exposed Shock or Arc Flash Hazard Exposed to operate Switchto operate Switch



Idaho National Laboratory, Radioactive Waste Management Complex

On May 10, 2006 an RCT reported feeling an electrical shock on his bare right forearm as he was removing the electrical cord plug of a Continuous Air Monitor (CAM) vacuum pump from around the side and back of an Uninterruptible Power Supply (UPS). He felt what he considered to be an electrical shock when his forearm came into contact with the outside case of the UPS as he removed the 110 volt plug from the receptacle located on the back of the UPS.



Unexpected Electrical HazardsUnexpected Electrical Hazards

RCT RECEIVES SHOCK WHILE STARTING A CAM VACUUM PUMP

On 08/23/95, a Radiological Controls Technician (RCT) at T Plant received a mild shock when his hand brushed energized contacts inside an instrument cabinet. He was starting a vacuum pump for a continuous air monitor (CAM) and reached into the cabinet to verify pump operation. He was not injured.


Burned Wire on PCM-2 Personnel Contamination

Monitor Causes Facility Evacuation On 12/29/05 after exiting the 105KE Basin and proceeding to the PCM-2, an operator observed that the displays on the monitor were not working and heavy smoke was coming out of the top of the unit. The facility was evacuated and the monitor was unplugged. When Hanford Fire Department (HFD) personnel arrived they found no fire or smoke coming from the monitor.


Unguarded Temporary LightUnguarded Temporary Light

Exposes energized parts.Exposes energized parts.

Unexpected Electrical HazardsUnexpected Electrical Hazards


Working on or NearExposed Energized Parts

Unqualified Persons, Safe Approach Distance:

– Unqualified persons are safe when they maintain a distance from the exposed energized conductors or circuit parts.

– The safe approach distance is the Limited Approach Boundary.


LAB

50 to 300 V

Exposed Movable Parts

10 feet

LAB

50 to 300 V

Exposed Fixed Parts

3.5 feet


NFPA 70E Standard for Electrical Safety Requirements for Employee Workplaces

Table 2-1.3.4 Approach Boundaries to Live Parts for Shock Protection. (All dimensions are distance from live part to employee.)

(1) (2) (3) (4) (5)

Limited Approach

Boundary1

Restricted Approach

Boundary1

Nominal System Voltage Range,

Phase to Phase

Exposed Movable

Conductor

Exposed Fixed Circuit Part

Includes Inadvertent

Movement Adder

Prohibited Approach

Boundary1

0 to 50 Not specified Not specified Not specified Not specified

51 to 300 10 ft 0 in. 3 ft 6 in. Avoid contact Avoid contact

301 to 750 10 ft 0 in. 3 ft 6 in. 1 ft 0 in. 0 ft 1 in.

751 to 15 kV 10 ft 0 in. 5 ft 0 in. 2 ft 2 in 0 ft 7 in.

15.1 kV to 36 kV 10 ft 0 in. 6 ft 0 in. 2 ft 7 in. 0 ft 10 in

36.1 kV to 46 kV 10 ft 0 in. 8 ft 0 in. 2 ft 9 in. 1 ft 5 in.

46.1 kV to 72.5 kV

10 ft 0 in. 8 ft 0 in. 3 ft 3 in. 2 ft 1 in.

72.6 kV to 121 kV 10 ft 0 in. 8 ft 0 in. 3 ft 2 in. 2 ft 8 in.

138 kV to 145 kV 11 ft 0 in. 10 ft 0 in. 3 ft 7 in. 3 ft 1 in.

161 kV to 169 kV 11 ft 0 in. 11 ft 8 in 4 ft 0 in. 3 ft 6 in.



The Flash Protection Boundary is 4 ft. for systems 600 volts and below unless calculated otherwise under engineering supervision.



Temperature And Heat DataTemperature And Heat Data

• Curable burn temperature (1/10sec) 145 °F

• Cell death temperature (1/10 sec) 205 °F

• Temperature at arc terminals 35,000 °F

• Temperature of suns surface 9,000 °F

• Temperature of burning clothing 1,400 °F

• Clothing ignition temperature 700 to 1,400 °F

• Temperature of metal droplets 1,800 °F



Unqualified Persons, Safe Approach Distance:

• Unqualified persons must not cross the Flash Protection Boundary unless they are wearing the appropriate PPE and under the supervision of a qualified person.


Electrical Burns vs Occupational burns OSHA - 1996

Type of Burn % of Total % of

Permanently Disabled

Scald 38 6.5 Flame 30 10.0

Tar 16 14.3 Electrical 8 86.7 Contact 4 25.0

Chemical 4 50.0



CPPCPP 19821982 RollRoll inin BreakerBreaker






Consequences of an Arc-Flash IncidentConsequences of an Arc-Flash Incident


Consequences of an Arc-Flash IncidentConsequences of an Arc-Flash Incident

Review the list of items shown in slide.In this case the worker wasn’t shocked he was caught in an Arc Flash.


Brookhaven 4/2006 Arc-Flash IncidentBrookhaven 4/2006 Arc-Flash Incident








Common Electrical Exposures for

RCTs




Hole in Mylar


Thin wires (hard to see)



2100 Volts DC


Possible exposure

Eberline CAM


Possible exposure

Canberra CAM

Possible exposure


Electricity is a part of our daily lives, harness its power but recognize the hazards.

Documents

EFCOG Electrical Safety Task Group ELECTRICAL SAFETY FOR RADIOLOGICAL CONTROL TECHNICIANS EFCOG Electrical Safety Task Group Module 7