.
Created: 1999-01-08
Last edited: 2001-08-08
Subjects:
Grounding is Safety & Reliability.
Prod 990108 Rev. 0
Author : Augusto Mendoza-Martinez
Meanings.- . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 01
- Grounding is a confusing word ... , sometimes it is related to the common
meaning of "ground" [ earth, soil, ...]; some
others and more frequently its meaning is connected
to.... some special way of install or connect, that
provides facts that control some risks or dangers to
people, equipment and property.
- Safety isn’t the lack of danger, that is
never a truth, we all have to live with some risks. Al
what one can do is to control the appearance of dangerous
situations, or to produce some automatic actions to
reduce the time during the dangerous situation is
present, or to have automatic means to reduce the time,
magnitude or both of events, and the physical or
biological effects on persons, livestock, equipment,
property .....
- Reliability is related to the lack of failures of the
service you get from an equipment or the installation to
make it works; it ‘s related too with some important
needs or production that relies on the equipment or its
appropriate functioning. What happens with your meat if
your freezer stops?
Facts.- . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .
. . . . . . . . . .02
- Not properly Grounded installations or equipment connections
can produce, from failures to very serious injures and
even death to people, directly from electrical biological
effects or indirectly from fires or not functioning of
certain equipment or services.
- Codes and Standards provide rules and technical support to
the planners, constructors and maintenance people to do
the right way .
I do recommend.- . . . . . . . . . . . . .
. . . . . . . . . . . . . .. . . . . . . . 03
- Review , or make others do, your installation
and equipment connections to be sure them are properly
grounded.
- Be in a hurry to search qualified advice and action if
you find some of the following situations: feel some
electrical sensation when touching some of your
electrical devices, found some electrical wiring too hot,
knows your property’s electrical installation has
been built or modified by non qualified workers or
without appropriated supervision.
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Use
of Electrical Energy -
Safety & Reliability.
Produced: 990109
Review: 0
Author : Augusto
Mendoza-Martinez
Concepts. . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . 01
- All kinds of useful
energy have its harm potential;
misused, or out of certain control, it can become in a
fire, lost of property, injure to live beings, or
death...... Think in combustion, moving or falling water,
foods, ....
- Electrical Energy
is used to get light, heat, mechanical power to
transport, work, refrigerating, electronics, and so on.
... It is present with its damage potential at home, at
workplaces, in the transport means ...,
- Electrical Energy is carried to devices with
connections of conducting metal wires with insulating
[not conducting] covers and specific devices like
transformers, movile connecting devices, disconnecting
means, that must be used within limits of temperature in
order no to loss its properties or being damaged.
- Electric energy transport produces heat in the
metal of all connection metal [the greater the size of
the conductor wire or metal part, the less heat produced
by the same amount of energy transported] . That means a
conductor or electrical equipment has a limit to
transport Electrical Energy, beyond which the metal can
overheat the insulating cover, case or support.
Facts. . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . 02
- With no insulation o damaged insulation,
conductors can make contact with metal parts o other
conductor's metal. This is what electricians call
"short circuit"; in such a situation energy
flows out of control and produces a large amount of heat.
A chain reaction of more damage, more heat, ... very soon
start a fire and very often an explosion.
- Loss of insulation may also permit users of
equipment become in contact with conductors or metal
parts connected with electrical conductors. Because
flesh, blood, and other tissues are not insulating
materials, energy goes thorough: heating, burning,
disturbing vital functions, ...... injuring or killing.
- Even the simple heat from overheated, still not
damaged conductors or equipment, under certain conditions
may result in fires or explosions.
I do recommend. . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . 03
- Every section of electrical systems must have
devices to control the amount of electrical energy to be
transported, matched with the electrical conductors,
connection devices and equipment ability. This devices .
- All the above set of protecting devices [fuses,
circuit breakers, etc. ] provide risk control
disconnecting the flow of energy, they stop the use of
the energy and the benefits of such use.
- Electrical Codes and Standards resume guides to
select and use protecting devices, well qualified
technicians must evaluate all present factors such as
ambient temperatures, kind of materials, use, etc.
- In new installations, planning must be made by
experienced designers and construction supervised to
fulfill the technical requirements both to have risk
control well designed to maintain service or reestablish
it as soon as the property or process permit.
- Existing installations must be surveyed on
electrical safety aspects at least each five years or
after changes in use are made.
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Electrical
Safety Survey Check List.
Produced: 990130
Review: 0
Author : Augusto
Mendoza-Martinez
The following list is aimed to electrical
engineers and technicians as well as to non-specialist users with
qualified support. If used please make reference to author
indicating e-mail address; if in web site used please link to my
site. Hope be useful to you.
SERVICE. . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . 1.0
a. Service
location. Where the electrical energy
meter by utility is. There must exist also a general
disconnecting mean or means to shutoff all energy supply to
property.
01- Security to prevent tampering
of installation or operation by intruders.
02- Absence and prevention to
presence of water, dust, gas, insects.
03- Known marked and easy access
to disconnecting means in case of an emergency.
04- Reliability of devices used
to disconnect energy.
05- Tightness of all electrical
means of connecting cables.
06- Presence of high temperature
[more than 80 C or 176 F], high temperature signals of
damage on insulation, burnouts.
07- Estrange like soldering or
welding smell.
08- Running of meter after
disconnecting all consuming equipment. Energy leaks
Symptom.
09- Rated interrupting power of
protective equipment adequate to site.
10- Ampere rating of conductors
adequate to power transmitted.
11- Ampere rating of overcurrent
protectors adequate to protected installation.
b. At
Service location grounding. A
grounding installation that connects the neutral conductor at the
box, cabinet o other enclosure where the main disconnecting mean
or means are.
- 01- Neutral to grounding conductor connection
tight and reliable.
- 02- Grounding conductor referenced by reliable
connection to metal of enclosure.
- 03- Grounding conductor referenced by reliable
connection to premises or property construction and metal
water piping system.
- 04- Grounding conductor referenced by reliable
connection to earth [natural soil].
- 05- Zero or negligible under circumstances of
site, current in grounding conductors.
- 06- Zero or negligible volt measurement between
metallic grounded parts and neutral conductor.
- 07- Physical disposition to control danger to
life because of Ground Potential Rise. High Voltage
Services.
c. Lightning and surge protection.
A protective mean and installation to guaranty some safety degree
in case of.
- 01- Rating, type, relative position. Matched to
site conditions.
- 02- Grounding to earth and ground referenced
service entrance conductor.
- 03- Presence of high temperature signals, damage
on insulation, burnout.
- 04- Reliability of devices used to by-pass
abnormal energy safely to ground / earth.
- 05- Physical disposition of grounding to control
danger to life because of Ground Potential Rise.
d. Maintenance.
Easiness to find equipment and parts to replace them.
- 01- Type and size of fuses if used.
- 02-Model of circuit breakers and fixing means.
- 03- Replacing spare parts to buy to be ready.
- 04- Reliability of devices used / possibility /
need to upgrade.
e. What could happened if.
Imagine situations that can lead to undesired
events, prevention, and protection. Reduce if I could have
imagined.
- 01- Child, very old people, not normal people, or
similars, actions.
- 02- Sneak, apes, rats, etc. presence.
- 04- Earthquake, flow, flying or falling objects,
other nature events.
PANELBOARDS or SWITCHBOARDS. . . . . . . . . . . . . . . . . . 2.0
a. Panelboard or Switchboard
location. These pieces of
electrical system equipment where energy is distributed in a like
tree topology [big and more important to smaller and less
important branches] include a set of disconnecting and protecting
devices for protection and control.
- 01- Security to prevent tampering of installation
or operation by intruders.
- 02- Absence and prevention to presence of water,
dust, gas, insects or other animals.
- 03- Known marked and easy access to disconnecting
means main and of branches in case of emergency.
- 04- Reliability of devices used to disconnect
energy.
- 05- Tightness of all electrical means of
connecting cables and devices.
- 06- Presence of high temperature [more than 80 C
or 176 F], high temperature signals of damage on
insulation, burnouts.
- 07- Estrange like soldering or welding smell.
- 08- Hum or like bees sounds.
- 09- Rated interrupting power of protective
equipment adequate to site.
- 10- Ampere rating of conductors adequate to power
transmitted.
- 11- Ampere rating of overcurrent protectors
adequate to protected installation.
- 12- Updated drawings or forms and field marks
that permit know relation of devices with wiring.
- 13- History of load measurements periodically
made.
- 14- Availability of replacement parts or devices.
- 15- Abnormal temperature or smoke detection and
alarm system.
- 16- Fire extinction means.
- 17- Written instruction to user for safety and
proper use.
- 18- Exit means and free space to maintain and use
safely.
b. At Panelboard or switchboard,
grounding. A grounding installation
that guaranties the box, cabinet o other enclosure and metallic
pieces be referenced to what constitutes the reference ground of
electrical system to protect life and property. Special grounding
disposition and connections where a Separate Grounding System
exists because of using sensitive electronics.
- 01- Grounding conductor[s] connection tight and
reliable.
- 02- Grounding conductor referenced by reliable
connection to enclosure metal.
- 03- Zero or negligible under circumstances of
site, current in grounding conductors.
- 04- Zero or negligible volt measurement between
metallic grounded parts and neutral conductor.
- 05- Physical disposition to control danger to
life because of Ground Potential Rise. High Voltage
Switchboards.
c. Surge protection.
A protective mean and installation to guaranty some safety degree
in case of.
- 01- Rating, type, relative position. Matched to
site conditions.
- 02- Grounding to earth and ground conductor.
- 03- Presence of high temperature signals, damage
on insulation, burnout.
- 04- Reliability of devices used to by-pass
abnormal energy safely to ground / earth.
- 05- Physical disposition of grounding to control
danger to life because of Ground Potential Rise.
d. Maintenance.
Easiness to find equipment and parts to replace them.
- 01- Type and size of fuses if used.
- 02- Model of circuit breakers and fixing means.
- 03- Replacing spare parts to buy to be ready.
- 04- Reliability of devices used / possibility /
need to upgrade.
e. What could happened if.
Imagine situations that can lead to undesired events, prevention,
and protection. Reduce " if I could have imagined ".
- 01- Child, very old people or not normal people
actions.
- 02- Sneak, apes, rats, etc. presence.
- 04- Earthquake, flow, flying objects, other
nature events.
FEEDERS SYSTEM.
. . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . 3.0
a. Location.
These parts of electrical system, are the big branches of the
distribution of energy tree, connect one distribution equipment
[panelboard or switchboard] to other of less importance served
from the first. Include conductors [cables or bars] and covers
for physical defense and isolation most times referred as the
wireways.
- 01- Security to prevent tampering of installation
or damage by intruders.
- 02- Absence and prevention to presence of water,
dust, gas, insects or other animals.
- 03- Not routed through places that can contain
material that can explode or ignite in case of electrical
failure. So constructed to control such hazard in comply
with NEC / NFPA standards.
- 04- Reliability of conduit, tubes o other
wireways used to protect and contain cables, at the
ambient existent conditions.
- 05- Tightness of all mechanical and electrical
means of connecting different pieces of wireway and to
covers of equipment where they have an end.
- 06- Presence of high temperature [more than 80 C
or 176 F], high temperature signals of damage, burnout.
- 07- Estrange like soldering or welding smell. 08
Hum or like bees sounds.
- 09- Cable fixing to protect in case of mechanical
short circuit forces.
- 10- Ampere rating of conductors adequate to power
transmitted.
- 11- Ampere rating of overcurrent protectors
adequate to each part of installation.
- 12- Volt measurements within tolerance limits at
each stage of electrical system.
- 13- Updated drawings or forms and field marks to
easily know relation of schemes with wiring.
- 14- Reliability of supporting means to wall,
roof, structure, ceiling, etc.
- 15- Availability of replacement parts or devices
if bars, or not common material used.
- 16- Abnormal temperature or smoke detection and
alarm system when property worhts it.
- 17- Fire extinction means coordinated to best
results in case of using.
- 18- Adequate clearances, barriers and signals to
no been hit by cars, objects, or injure people passing
by.
- 19- Moving mechanical connections to avoid
damages of installation by dilatation, different metal
dilatation, and relative movement of different structure
parts of building or support structures.
- 20- Dangerous painting, because of dark color sun
heat absorption.
b. Feeders Grounding.
All grounding means to guaranty the real
connection of all metal, to what constitutes the reference ground
of electrical system to protect life and property, but in the
specific way asked by standards to be effective. Special
grounding disposition and connections must be used where a
Separate Grounding System exists because of sensitive
electronics.
- 01- Grounding conductor [s] connection tight and
reliable.
- 02- Grounding conductor referenced by reliable
connection to enclosures metal.
- 03- Zero or negligible under circumstances of
site, current in grounding conductors.
- 04- Zero or negligible volt measurement between
metallic grounded parts and neutral conductor.
- 05- Physical disposition to control danger to
life because Transferred Potential or Ground Potential
Rise.
c. At boxes, Handholes, Manholes o
Vaults. Elements of installation to
easy wiring work, accessible to inspect.
- 01- Relative position of different conductor
inside.
- 02-Grounding to earth and ground conductor of
metal conduits.
- 03- Presence of high temperature signals, damage
on insulation, burnout.
- 04- Identification marks to easily relate
physical to drawings.
- 05- Sealing of conduit where needed.
- 06- Reliability of box, manhole or vault cover
[s],
- 07- Clearances and easy access to open, maintain,
inspect.
- 08- Drain means effective. Condensing or rain
water.
- 09- Design or means to prevent falling covers
damages or accidents.
- 10- Support and structural stage or damages that
introduce some hazard.
d. Maintenance.
Easiness to find equipment and parts to replace them.
- 01- Type and size of Busbar system pieces where
used.
- 02- Terminal and connectors.
- 03- Replacing spare parts to buy to be ready.
- 04- Reliability of material used / possibility /
need to upgrade.
e. What could happened if.
Imagine situations that can lead to undesired events, prevention,
and protection. Reduce if I could have imagined.
- 01- Child, very old people or not normal people
actions.
- 02- Sneak, apes, rats, etc. presence.
- 04- Earthquake, flow, flying objects, other
nature events.
- 05- Digging dangers on gardens or parkings.
BRANCH CIRCUITS AND OUTLETS. . . . . . .. . . . . . . . . .
. .. 4.0
a. Location. These
parts of electrical system, are the LAST part of the fixed
electrical system, at the equipment connection end [downstream in
the sense of energy flow] they connect one distribution equipment
[panelboard or switchboard] to electrical energy consumer
equipment directly or by means of mobile connecting devices like
the common receptacle and plugs of the equipment or fixture cord.
Include conductors and covers for physical defense and isolation
most times referred as the wireways.
- 01- Security to prevent tampering of installation
or damage by intruders.
- 02- Absence and prevention to presence of water,
dust, gas, insects or other animals.
- 03- Not routed through places that can contain
material that can explode or ignite in case of electrical
failure. So constructed to control such hazard in comply
with NEC / NFPA standards.
- 04- Reliability of conduit, tubes o other
wireways used to protect and contain cables, at the
ambient existent conditions.
- 05- Tightness of all mechanical and electrical
means of connecting different pieces of wireway and to
covers of equipment where they have an end.
- 06- Presence of high temperature [more than 80 C
or 176 F], high temperature signals of damage, burnout.
- 07- Estrange like soldering or welding smell.
- 08- Hum or like bees sound.
- 09- Glowing at dark in contact points of devices
like receptacles or lighting switches
- 10- Ampere rating of conductors adequate to power
transmitted.
- 11- Ampere rating of overcurrent protectors
adequate to each size of conductor.
- 12- Volt measurements within tolerance limits at
most distant connection point.
- 13- Updated drawings or forms and field marks to
easily know relation of schemes with wiring.
- 14- Reliability of supporting means to wall,
roof, structure, ceiling, etc.
- 15- Availability of replacement parts or devices.
- 16- Adequate clearances, barriers and signals, to
no been hit by cars, objects, or injure people passing
by.
- 17- Moving mechanical connections to avoid
damages of installation by dilatation, different metal
dilatation, and relative movement of different structure
parts of building or support structure.
- 18- Dangerous painting, because of dark color sun
heat absorption.
b. Grounding. All
grounding means to guaranty the real connection of all metal, to
what constitutes the reference ground of electrical system to
protect life and property, but in the specific way asked by
standards to be effective. Special grounding disposition and
connections must be used where a Separate Grounding System exists
because of sensitive electronics.
- 01- Grounding conductor [s] connection tight and
reliable.
- 02- Grounding conductor referenced by reliable
connection to enclosures metal.
- 03- Zero or negligible under circumstances of
site, current in grounding conductors.
- 04- Zero or negligible volt measurement between
metallic grounded parts and neutral conductor.
- 05- Physical disposition to control danger to
life because Transferred Potential or Ground Potential
Rise.
- 06- Appropriate wiring devices to give safe
grounding to the movable connection and equipment.
c. At boxes or handholes.
Elements of installation to easy wiring work, accessible to
inspect.
- 01- Relative position of different conductor
inside.
- 02- Grounding to earth and ground conductor of
metal conduits.
- 03- Presence of high temperature signals, damage
on insulation, burnout.
- 04- Identification marks to easily relate
physical to drawings.
- 05- Sealing of conduit where needed.
- 06- Reliability of box or manhole cover.
- 07- Clearances and easy access to open, maintain,
inspect.
- 08- Drain means effective. Condensing or rain
water.
- 09- Design or means to prevent falling covers
damages or accidents.
- 10- Support and structural stage or damages that
introduce some hazard.
d. Maintenance.
Easiness to find equipment and parts to replace them.
- 01- Type of wiring devices and plates used.
- 02- Terminal and connectors.
- 03- Replacing spare parts to buy to be ready.
- 04- Reliability of material used / possibility /
need to upgrade.
e. What could happened if.
Imagine situations that can lead to undesired events,
prevention, and protection. Reduce if
I could have imagined.
- 01- Child, very old people or not normal people
actions.
- 02- Ants, apes, rats, etc. presence.
- 03- Car accidents at parkings.
- 04- Earthquake, flow, other nature events.
- 05- Digging dangers on gardens or parkings.
SYSTEM CONFIGURATION. . . . . . . . . . . . . . . . . . . . . . . . . .
. 5.0
a. Space disposition of electrical system
components and interconnections. Path of
energy flow from service entrance to loads.
- 01- Sequence of load distribution centers
downstream of energy trough the load.
- 02- Relation and coordination between physical or
administrative parts of building and electrical system
components.
- 03- Sequence or chains of protecting devices
coordinating selectively.
- 04- Routes of important installation out of
places where in case of fire can be unnecessarily
damaged.
- 05- Feasibility of provisional installation to
reestablish service in case of some important accident.
- 06- Possible dangers because of energy coming
from downstream installation.
- 07- Possible danger because of circuits from
different origins be connected during or because of
failures.
- 08- Lacks of necessary redundancy to guaranty
service to important or vital loads.
b. What could happened if.
Imagine situations that can lead to undesired events,
prevention, and protection. Reduce if
I could have imagined
.
- 01- Any one of equipment, feeders, etc become out
of service because of important damage.
- 02- If [01] and there is another abnormal
situation like; fire, flow, earthquake, etc. at the same
time.
- 03- Equipment failure or damage and no
replacement to repair available during certain time.
EMERGENCY SYSTEMS. . . . . . . . . . . . . . . . . . . . . . . . . .
. . .6.0
a. Solution. Different
solutions, equipment and installation to get backup energy to
important to life loads.
- 01- Security to prevent tampering of installation
or damage by intruders.
- 02- Physical protection or isolation to prevent
simultaneous damage with Normal System parts.
- 03- Configuration of system and operating means
to get service under all of the circumstances of normal
energy failure, including internal.
- 04- Reliability control to assure emergency
system be always ready to work.
- 05- Means of prime movers combustible supply to
longest of emergency possible situation.
- 07- Automatic control equipment operativity.
b. What could happened if.
Imagine situations that can lead to undesired
events, prevention, and protection. Reduce if I could have imagined.
- 01- Standby power under repair.
- 02- Power to start backup equipment.
- 03- Car accidents that damage power emergency
plant.
- 04- Earthquake, flow, other nature events during
emergency system use.
c. Please use the same check items above for different
parts of emergency system if it exist.
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