A. Arc Flash hazard analysis gives the amount of energy
that release when an arc flash incident occurs. With this flash
protection boundary can be defined and also to determine the level of
arc-rated personal protective equipment required when employees cross
the boundary while they work on or near exposed live parts.
2. What are arc flash hazard labels?
A. Arc flash Labels provides the information of
hazardous level of the equipment or the system. It also gives the
information to the workmen about the boundary levels to operate when in
live condition. These labels are designed by considering the NFPA 70E
and OSHA standards.
3. How to design NFPA 70e labels?
A. NFPA 70e labels are designed based on the knowledge
of workmen and also the levels of arc flash. Mainly these labels should
contain the information of level of incident energy, different
boundaries and the PPE to be used based on the category.
4. What are arc flash electrical safety equipment?
A. Arc Flash electrical safety equipment is commonly
known as arc flash Personal Protective Equipment (PPE) which safeguards
the workmen while working with the panels in live operating condition.
These are categorized based on the incident energy which releases at the
time of arc fault.
5.How to use arc flash safety glasses?
A. Arc flash safety glasses are different from the
normal safety glasses which are used by the workmen. These should be
used while working on the live energized equipment. These are also
should be used based on the category which gives the protection when any
flash occur.
6. Why to use arc flash label printer?
A. Arc flash label printer is different from normally
used printers. A specific format and standard sizes are used with the
arc flash label printer. This printer designed to print the arc flash
label stickers from the standards of NFPA and OSHA which are used to
paste at the every individual feeder.
7. What Nfpa 70e says about electrical safety?
A. NFPA 70E purely says about electrical safety related
work practices of the employees during the period of maintenance,
operation, installation, testing and calibration and other related
electrical work practices which expose the workmen to the electrical
hazards. The work practices may be at the workshops, garages, buildings,
warehouses.
8. What kind of arc flash hearing protection is required for dangerous
category?
A. NFPA 70E recommends the workmen would not to work on
equipment in live condition when they are in dangerous category. So no
specific hearing protection is provided for dangerous category. From the
revision of NFPA 2012 normally used hearing protection is mandated for
all categories.
9. What is arc flash clothing and how to determine the arc flash Ppe?
A. Arc Flash Clothing is a safeguard for the workmen who
works at the equipment in live condition. This is also known as Personal
Protective Equipment (PPE). Th arc flash Ppe can be determined easily
because it looks completely different from general Ppe used by the
workmen in the industries. This Ppe should be used while operating with
the breakers and at the tie of maintenance of the breaker.
10. Why to use arc flash study software for arc flash hazard
calculations?
A. Arc flash hazard calculations are linked with the
logarithmic formulas and other equations and also related with the
terms, so it is difficult to calculate with these formulas for
individual feeders, it is time taken process. To reduce this process
software’s are used.
11. Why should I use electrical Ppe?
A. The Ppe plays a major role in protecting the workmen
from shocks. Ppe includes such as safety helmets, safety shoes, gloves,
high visibility clothing, eye protection…When you are using Ppe on
working stations that indicates you are in safe side.
12. What is arc flash category table?
A. Based on the incident energy levels generated at the
electrical equipment NFPA defined in category table. This category table
provides the information of incident energy range and respective
category.
13.Can I get arc flash safety training?
A. VB Engineering provides the arc flash safety training
to the workmen about the arc flash hazard and also the safety measures
to be followed at the time of maintenance and operation of breakers. The
general training is not related with the arc flash study.
14.How to read electrical warning labels?
A. Electrical warning labels are generally provided at
all the areas of electrical equipment. These provide only the
information of risk at the particular location. These are denoted by the
symbols of shock and danger (D). If the shock symbol is mentioned it
means don’t touch the equipment there is a possibility of shock,
similarly if Danger (D) is mentioned don’t touch the equipment and don’t
move forward to this location.
15.How to read arc flash warning labels?
A. Arc flash labels are defined such that a layman working at the
equipment can understand the label. So, labels are designed in
particular format. They are:
a) Category of the equipment is mentioned on the label.
b) Depending on the category label color changes.
c) Flash protection boundary is mentioned on the label.
d) Incident energy of the equipment is represented on the label.
16.How to define safety electric work procedures?
A. From the electrical based trainings the workmen and
laymen gets knowledge about the safety electric work procedures. General
electric work procedures are wearing safety shoes, safety gloves,
holding the tools carefully while working, working under the observation
of maintenance people, using hearing protection at required locations.
17.What are the causes of arc flash?
A. When current flows through an air gap between two conductors then arc
flash happens. Arc flash can also can caused by breaks are gaps in the
insulations, improper installation, corrosion or other impurities on the
surface of the conductor.
18. What are Nfpa 70e arc flash requirements?
A. The requirements of the NEFA-70E for arc flash
boundary is personal protective equipment access to reference tables,
personal protective equipment matrix, equipment selection electrical
assessments, signage, proper storage and training.
19. What is arc fault breaker and how to use it?
A. Arc fault breaker is specially designed breaker used
to get disconnecting the power by detecting the electrical arc at the
time of fault prevents from the fire accidents and arc flash accidents.
Before going to use this devices initially we have to identify the
specific structure and specific destinations where this breaker is
really applicable.
20. What are arc flash boundaries and how to determine them?
A. Arc flash boundaries are three types they are
limited, restricted, prohibited boundaries. These boundaries are
determined by Categories of incident energy across the protective
devices.
21. How to design arc flash labels?
A. The word danger is appears in white letters on red
background, it indicates the most dangers threats. The word warning is
appears in black letters on an orange background. And arc flash warning
labels carry additional information beyond what is required by law.
22. How are arc flash relays operated?
A. Arc flash relays are one of the best solutions to
prevent arc flash hazards. This arc flash relay operates with the use of
light sensors. A sensor is placed in the equipment’s chamber. This
sensor senses the spark or light and after certain level of light it
automatically trips the relay so that arc flash can be reduced.
23. How to prevent arc flash accidents?
A.People must be aware about the arc flash accidents why
it is happening. And people wearing proper Ppe in working stations. The
people fallows the cautions and rules of NFPA. Then preventing the arc
flash accidents.
24. How to mitigate arc flash hazard analysis?
A. Mitigation of arc flash hazard can be achieved by
following proper methods like mandating the work permits for the persons
working on the equipment, wearing proper PPE while working on the
equipment, allowing qualified and trained persons only to the equipment,
using electrical arc detecting equipment, performing relay coordination
etc. By following these procedures electrical arc hazards can be
mitigated or reduced.
25. What are arc rated shirts?
A. The rated shirts are designed to provide to withstand
from heat and flame.to minimize the total burn injury. Our rated shirts
and sweat shirts also help to provide the wearer with extra secondary
protection to help escape possibility secondary explosion in work space.
26. Where can I get full information about arc flash hazards and its
mitigation?
A. From the standards of NFPA we can get the information
about the arc flash hazards and its mitigation and for the calculation
formulas we have to refer the IEEE 1584 standards and for the codes ,
shortcuts ,abbreviations simply we have to refer the NEC standard books.
27. What is ieee1584?
A. IEEE1584 is a standard which came from the Institute
of electrical and electronic engineers. This IEEE1584 provides us
different ways and methods for measuring and calculating incident energy
whenever arc flash occurs. Its main aim is to protect people from arc
flash hazards by defining guidelines. It also defines safe working
distance.
28. How are OSHA fines for arc flash accidents?
A. Occupational Health Safety Administration (OSHA)
deals with the safety of the employee mainly. As per OSHA employer must
provide safe environment to the employee. In case of any violation of
this or any accident due to unsafe work areas, OSHA imposes fines to the
companies as much as 5, 00,000 dollars. OSHA proposes companies to
follow NFPA70E guidelines for safety.
29. What are arc flash suits and how to use them?
A. Arc flash suits are specially designed arc rated
clothing which safeguards the workmen from the arc flash hazard. These
are to be used based on the category levels referred from the arc flash
labels. This arc flash suit is a complete body cover.
30. What is limited approach?
A. Limited approach boundary is one which can be crossed
only by a qualified person. An un-qualified person can also enter in to
this boundary when escorted and guided by a qualified person. This
boundary is the minimum level behind which unqualified personal should
stand.
31. What is personnel protective equipment?
A. Personnel protective equipment means clothes,
helmets, goggles or other equipment designed to protect body from damage
or injury or even death. These personnel protective equipment are
designed to cope with hazards like electrical, chemical, heat etc. These
PPE are must while working in dangerous conditions.
32.What is restricted approach?
A. Restricted approach boundary in to which qualified
personal only allowed who undergone respective training on this and has
to wear proper PPE. Due to its proximity to shock, personal should us
shock protection techniques and equipment. Also, personal must have the
approved plan for the work that is going to perform.
33. How to determine arc flash ?
A. Arc flash boundary is determined by the expansion or
explosion of arc when a fault of short circuit occurs. These are
calculated by the arc flash study and from the arc flash labels pasted
at the panels the workmen and the laymen can find the distance while
moving around the electrical equipment.
34. What is flash protection boundary and prohibited approach?
A. Flash protection boundary is the longest distant
boundary from the energy source. If an arc flash occurs, a person at
this boundary can receive second degree burn. A prohibited approach
boundary in to which only qualified professionals can enter into it with
respective PPE must.
35.Where can I get arc flash certification?
A. Arc flash certifications is provided to the workmen
and laymen whose gains the knowledge about the arc flash hazards and the
safety measures to be followed. These certifications are provided by the
arc flash trainers at the time of arc flash training held at the
facility and also a special courses is available for normal people.
These certificates are no way related to NFPA and OSHA only standards of
NFPA and OSHA are discussed.
36. Is arc flash analysis a scientific approach?
A.Yes it is a scientific approach because for conducting
the arc flash analysis no hand calculations are performed only the
standard formulas are considered for calculations. While the study no
practical visualization is not shown at the electrical equipment.
37. What are arc flash warning signs?
A. Arc flash warning signs are used to identify the
categories for the particular equipment. For every category a specially
designed arc flash suits are to be wear while maintenance. The signs are
generally denoted as 0,1,2,3,4 and D. D is for the Dangerous category
and the other are category-0,1,2,3,4.
38. What is an arc fault?
A. An arc fault is defined as the high power discharge
of current or electricity between two or more conductors. This fault can
generate heat which can break down wire’s insulation and possibly can
trigger fire. This arc fault can cause huge damage to the equipment and
even injure/kill people.
39. What kind of Ppe should be used for arc flash category no 4?
A. Following PPE should be used for category no 4:
a) Cotton Underwear,
b) Short sleeved T shirt,
c) FR long sleeved shirt & long pants,
d) FR coverall,
e) Arc flash suit hood,
f) Arc flash suit jacket,
g) Arc flash suit pants,
h) Hard Hat,
i) Safety glasses or goggles,
j) Hearing Protection,
k) Leather gloves and shoes as needed.
40. What kind of Ppe should be used for arc flash category no 3?
A. Following PPE should be used for category no 3:
a) Cotton Underwear,
b) Short sleeved T shirt,
c) FR long sleeved shirt & long pants,
d) FR coverall,
e) Arc flash suit hood,
f) Hard Hat,
g) Safety glasses or goggles,
h) Hearing Protection,
i) Leather gloves and shoes as needed.
41. What kind of Ppe should be used for arc flash category no 2?
A. Following PPE should be used for category no 2:
a) Cotton Underwear,
b) Short sleeved T shirt,
c) FR long sleeved shirt & pants or FR covered instead,
d) Arc rated wrap around face shield,
e) Hard Hat,
f) Safety glasses or goggles,
g) Hearing Protection,
h) Leather gloves and shoes as needed.
42. What kind of Ppe should be used for arc flash category no 1?
A. Following PPE should be used for category no 1:
a) Cotton Underwear,
b) FR long sleeved shirt & pants or FR covered instead,
c) Hard Hat,
d) Safety glasses or goggles,
e) Leather gloves and shoes as needed.
43. What kind of Ppe should be used for dangerous category?
A. As per NFPA 70E safety guidelines, there is no PPE
for dangerous category. Because, dangerous category means the incident
energy at the devise is more than 40 cal/cm^2. So, the devise is
dangerous to work even with PPE. In order to work on those devices, it
is recommended that power supply to be cut off.
44. What is the difference between bolted short circuit and arcing short
circuit?
A. Both types of short circuit currents are dangerous
and cause arc flash accidents. But, both are different in terms of their
characteristics. Bolted short circuit occurs when two live conductors
get into contact. Whereas arcing short circuit occurs when there exist
arc between two live conductors. This arc is formed due to many reasons
like poor maintenance, dust, loose connections etc., Between these two,
Arcing short circuit is much dangerous than bolted short circuit.
45. Why more fire accidents happen because of arc flash hazards?
A. When arc flash hazards happens high amount of
incident energy is generated due to the delay in fault interruptions. If
the more time taken to interrupt the fault the energy releases is high.
The incident energy is a form of fire. To reduce these accidents arc
flash relay are used which detects the light and trips the device
faster.
46. What is short circuit and how to interrupt it?
A. When a direct contact or indirect contact between two
live conductors is developed it leads a short circuit, this short
circuit produces a fault in the system which creates a serious
disturbances in the facility. The time taken to interrupt the fault
happens due to short circuit produces a flash over at the feeders. The
early fault clearance or interruption creates less disturbances in the
system.
47. What is relay coordination and how to achieve it for successful
short circuit interruption?
A. Relay coordination study is conducted between the
protective devices to check whether the facility related devices are in
coordination or not. This study is done with the short circuit
interruption values. After the study recommendations are provided if
required. When the system is in coordination automatically the short
circuit interruption is in normal condition only.
48. Is arc flash analysis practiced in India?
A. The expansion of MNC based manufacturing plants are
increased and they follow the standards of NFPA and OSHA made the
culture of the plant safety studies. Arc flash analysis is one of the
safety study which mainly recommends the suggestions the facility from
accident free zone to the workmen from electrical accidents.
49. What is incident energy?
A. Incident energy is the energy impressed on a surface
at a working distance, D from the arc source. The unit by which Incident
energy is represented is cal/cm^2. The working distance, D is the
distance from where worker stands to the fault location. Incident energy
is the function of system voltage, available SC current, arc current and
time required for protective device to open.
50. How to reduce incident energy?
A. Incident energy is calculated from device tripping
time, the time taken by the device when a fault occurs for a particular
short circuit value. If we decrease the tripping time which means a
breaker opening time incident energy can be reduced. This reduction is
recommended only after performing relay coordination study only.