Panel Sizes
Contrary to popular opinion, the size of the electrical service to your house
is not necessarily the rating stamped on the electrical panel cover. That
marking is the maximum capacity of the panel. The panel, the main circuit
breakers (or fuses), and the service entrance cable (SEC) must all have a
100 amp capacity for you to have a 100 amp service. For example: a 200
amp panel with a 100 amp SEC and a 100 amp main circuit breaker
means the house has a 100 amp electrical service. The size and material
(copper or aluminum) of the SEC determines its capacity. In most cases,
the SEC capacity is the limiting factor which determines the electrical
service capacity.
Most houses built in the last 30 years have at least a 100 amp electrical
service, although many smaller, older homes have been getting along
adequately with a 60 amp electrical service as long as they have gas
appliances, gas equipment and no central air conditioning.
Ground Fault Circuits Interrupters (GFCI)
A ground fault circuit interrupter (GFCI) is a safety device installed to
protect you when using electrical devices in wet locations. When using an
electrical device under normal conditions, the same amount of current
(amps) flows in the "hot" wire and the "neutral" wire. The ground fault
circuit interrupter measures the difference between the current in the "hot"
and neutral wires. If your body becomes the path of least resistance, the
current flows through you, reducing the current in the neutral wire. If the
difference in currents in the "hot" and neutral wires is more than 5
Milliamps, the ground fault circuit interrupter senses this and shuts off the
power to that outlet in approximately one fortieth of one second.
Ground fault circuit interrupters come in 2 types: ground fault electrical
outlets and ground fault circuit breakers. Both have the same function.
Ground fault electrical outlets are the ones with the "test" and "reset"
buttons on them. Ground fault circuit breakers are the ones in your
electrical panel with a "test" button on them. Both types should be tested
once a month to make sure the safety device is still working. Just because
there is power at a ground fault protected circuit doesn't necessarily mean
the safety device is working. It must be regularly tested. Approximately
20% of the ground fault safety devices that we test are not working.
Ground fault safety devices were originally required only in bathrooms
beginning about 1980. Gradually the code requirements have changed to
include all "wet" (within 6 feet of a water source) locations in and around
the home, such as bathrooms, kitchens, laundries, garages, whirlpools,
Jacuzzi's and exterior outlets. Several electrical outlets can be connected
to one ground fault safety device.
Arc Fault Circuit Interrupters (AFCI)
The AFCI (Arc Fault Circuit Interrupter) breaker, will shut off a circuit in a
fraction of a second if arcing develops. The current inside of an arc is not
always high enough to trip a regular breaker. You must have noticed a cut
or worn piece of a cord or a loose connection in a junction box or
receptacle arcing and burnt without tripping the regular breaker. As you
can guess this is a major cause of fires in a dwelling.
There is a difference between AFCIs and GFCIs. AFCIs are intended to
reduce the likelihood of fire caused by electrical arcing faults; whereas,
GFCIs are personnel protection intended to reduce the likelihood of
electric shock hazard. Don't misunderstand, GFCIs are still needed and
save a lot of lives.
Combination devices that include both AFCI and GFCI protection in one
unit will become available soon. AFCIs can be installed in any 15 or 20
ampere branch circuit in homes today and are currently available as circuit
breakers with built-in AFCI features. In the near future, other types of
devices with AFCI protection will be available.
If a GFCI receptacle is installed on the load side of an AFCI it is possible
for both the AFCI and the GFCI to trip on a fault if the current exceeds the
limit for both devices. It is also possible for the AFCI to trip and the GFCI to
not trip since the two devices could race each other. However, in no case
is safety compromised.
At first the cost for AFCI will be high. Expect to pay between $20 and $50
for each AFCI. The cost is expected to drop as much more are ordered.
Over Current Protection Devices
Over Current protection devices (fuses and circuit breakers) are designed
to protect the wires connected to them. They limit the current (amperes)
flowing through the wire to prevent it from overheating. An overheated wire
could melt its insulation and cause a fire. Over current protection devices
come in two types: Circuit Breakers and Fuses. Each size fuse or circuit
breaker is made to be connected to a particular wire material and size.
Fifteen amp fuses or circuit breakers should be connected to a #14 solid
copper wire. Twenty amp fuses or circuit breakers should be connected to
a #12 solid copper wire. Thirty amp fuses or circuit breakers should be
connected to a #10 solid copper wire, etc. Oversized fuses or circuit
breakers are potentially dangerous. If a 30 amp circuit breaker or fuse has
a #12 solid copper wire connected to it, a potentially dangerous situation
exists. If 25 amps of current was flowing through the wire, which was only
rated to safely handle 20 amps, the wire will overheat and could cause a
fire. Since only 25 amps is flowing the 30 amp circuit breaker will not trip to
protect the wire. Oversized fuses or circuit breakers should be corrected
by a licensed electrician.
When we encounter a situation with over-sized fuses or breakers, we
frequently hear "It's been like that for years, and we've never had a
problem!". It was only luck that a fire didn't start.
Aluminum Branch Circuit Wiring
Circuits which use single solid aluminum wiring are considered a
significantly higher fire risk than copper wired circuits. Aluminum wiring is
not considered a safety hazard on multi- stranded wire used for major and
minor appliance circuits or feeders to panels and sub panels.
Solid aluminum circuit wires were used in tract housing built between 1964
and 1975. Some high-rise housing also utilized this wiring.
Aluminum wiring expands more when current flows through it than copper
wiring. Consequently aluminum wires can tend to work loose where they
are connected to panels and devices. The loose connections can arc and
cause a fire. Aluminum wire also appears to cause a chemical reaction
where it connects to some receptacles and switches. Aluminum oxide
forms at the connection points. Aluminum oxide is very resistant to
electrical current flow. The aluminum oxide heats up and creates an
intermittently hot connection. One in five houses with aluminum wire in the
general electrical circuits has an intermittent hot connection according to
government research.
Popping, snapping or heat from electrical devices are a warning. The U.S.
Consumer Product Safety Commission (CPSC) says the safest way to
repair aluminum lighting circuits to use "cop alum" connectors. This should
only be done by an electrician that specializes in this type of work. Many
professional electricians are not familiar with the required procedures.
This process is relatively expensive, but cheaper than a new house.
Maintenance
Homeowners should turn all circuit breakers off and on once per year to
clear the contacts of any corrosion which may form. The surface of the
circuit breakers should be periodically felt for "hot spots". If abnormally hot
spots are detected, a licensed electrician should be contacted to
investigate and make corrections. Make sure the service entrance cable
(SEC) has no tree branches touching it. Remove them if necessary. The
service entrance cable is attached to the service head. Make sure the
service head is still properly secured to the side of the house. If not,
resecure it. Your electrical panels are safety devices. Occasionally you
may need to get into it quickly to turn off a circuit breaker. Every panel
should have three feet of clear space in front of it at all times. (This is
actually a code requirement). Find another place to store those items!
Contrary to popular opinion, the size of the electrical service to your house
is not necessarily the rating stamped on the electrical panel cover. That
marking is the maximum capacity of the panel. The panel, the main circuit
breakers (or fuses), and the service entrance cable (SEC) must all have a
100 amp capacity for you to have a 100 amp service. For example: a 200
amp panel with a 100 amp SEC and a 100 amp main circuit breaker
means the house has a 100 amp electrical service. The size and material
(copper or aluminum) of the SEC determines its capacity. In most cases,
the SEC capacity is the limiting factor which determines the electrical
service capacity.
Most houses built in the last 30 years have at least a 100 amp electrical
service, although many smaller, older homes have been getting along
adequately with a 60 amp electrical service as long as they have gas
appliances, gas equipment and no central air conditioning.
Ground Fault Circuits Interrupters (GFCI)
A ground fault circuit interrupter (GFCI) is a safety device installed to
protect you when using electrical devices in wet locations. When using an
electrical device under normal conditions, the same amount of current
(amps) flows in the "hot" wire and the "neutral" wire. The ground fault
circuit interrupter measures the difference between the current in the "hot"
and neutral wires. If your body becomes the path of least resistance, the
current flows through you, reducing the current in the neutral wire. If the
difference in currents in the "hot" and neutral wires is more than 5
Milliamps, the ground fault circuit interrupter senses this and shuts off the
power to that outlet in approximately one fortieth of one second.
Ground fault circuit interrupters come in 2 types: ground fault electrical
outlets and ground fault circuit breakers. Both have the same function.
Ground fault electrical outlets are the ones with the "test" and "reset"
buttons on them. Ground fault circuit breakers are the ones in your
electrical panel with a "test" button on them. Both types should be tested
once a month to make sure the safety device is still working. Just because
there is power at a ground fault protected circuit doesn't necessarily mean
the safety device is working. It must be regularly tested. Approximately
20% of the ground fault safety devices that we test are not working.
Ground fault safety devices were originally required only in bathrooms
beginning about 1980. Gradually the code requirements have changed to
include all "wet" (within 6 feet of a water source) locations in and around
the home, such as bathrooms, kitchens, laundries, garages, whirlpools,
Jacuzzi's and exterior outlets. Several electrical outlets can be connected
to one ground fault safety device.
Arc Fault Circuit Interrupters (AFCI)
The AFCI (Arc Fault Circuit Interrupter) breaker, will shut off a circuit in a
fraction of a second if arcing develops. The current inside of an arc is not
always high enough to trip a regular breaker. You must have noticed a cut
or worn piece of a cord or a loose connection in a junction box or
receptacle arcing and burnt without tripping the regular breaker. As you
can guess this is a major cause of fires in a dwelling.
There is a difference between AFCIs and GFCIs. AFCIs are intended to
reduce the likelihood of fire caused by electrical arcing faults; whereas,
GFCIs are personnel protection intended to reduce the likelihood of
electric shock hazard. Don't misunderstand, GFCIs are still needed and
save a lot of lives.
Combination devices that include both AFCI and GFCI protection in one
unit will become available soon. AFCIs can be installed in any 15 or 20
ampere branch circuit in homes today and are currently available as circuit
breakers with built-in AFCI features. In the near future, other types of
devices with AFCI protection will be available.
If a GFCI receptacle is installed on the load side of an AFCI it is possible
for both the AFCI and the GFCI to trip on a fault if the current exceeds the
limit for both devices. It is also possible for the AFCI to trip and the GFCI to
not trip since the two devices could race each other. However, in no case
is safety compromised.
At first the cost for AFCI will be high. Expect to pay between $20 and $50
for each AFCI. The cost is expected to drop as much more are ordered.
Over Current Protection Devices
Over Current protection devices (fuses and circuit breakers) are designed
to protect the wires connected to them. They limit the current (amperes)
flowing through the wire to prevent it from overheating. An overheated wire
could melt its insulation and cause a fire. Over current protection devices
come in two types: Circuit Breakers and Fuses. Each size fuse or circuit
breaker is made to be connected to a particular wire material and size.
Fifteen amp fuses or circuit breakers should be connected to a #14 solid
copper wire. Twenty amp fuses or circuit breakers should be connected to
a #12 solid copper wire. Thirty amp fuses or circuit breakers should be
connected to a #10 solid copper wire, etc. Oversized fuses or circuit
breakers are potentially dangerous. If a 30 amp circuit breaker or fuse has
a #12 solid copper wire connected to it, a potentially dangerous situation
exists. If 25 amps of current was flowing through the wire, which was only
rated to safely handle 20 amps, the wire will overheat and could cause a
fire. Since only 25 amps is flowing the 30 amp circuit breaker will not trip to
protect the wire. Oversized fuses or circuit breakers should be corrected
by a licensed electrician.
When we encounter a situation with over-sized fuses or breakers, we
frequently hear "It's been like that for years, and we've never had a
problem!". It was only luck that a fire didn't start.
Aluminum Branch Circuit Wiring
Circuits which use single solid aluminum wiring are considered a
significantly higher fire risk than copper wired circuits. Aluminum wiring is
not considered a safety hazard on multi- stranded wire used for major and
minor appliance circuits or feeders to panels and sub panels.
Solid aluminum circuit wires were used in tract housing built between 1964
and 1975. Some high-rise housing also utilized this wiring.
Aluminum wiring expands more when current flows through it than copper
wiring. Consequently aluminum wires can tend to work loose where they
are connected to panels and devices. The loose connections can arc and
cause a fire. Aluminum wire also appears to cause a chemical reaction
where it connects to some receptacles and switches. Aluminum oxide
forms at the connection points. Aluminum oxide is very resistant to
electrical current flow. The aluminum oxide heats up and creates an
intermittently hot connection. One in five houses with aluminum wire in the
general electrical circuits has an intermittent hot connection according to
government research.
Popping, snapping or heat from electrical devices are a warning. The U.S.
Consumer Product Safety Commission (CPSC) says the safest way to
repair aluminum lighting circuits to use "cop alum" connectors. This should
only be done by an electrician that specializes in this type of work. Many
professional electricians are not familiar with the required procedures.
This process is relatively expensive, but cheaper than a new house.
Maintenance
Homeowners should turn all circuit breakers off and on once per year to
clear the contacts of any corrosion which may form. The surface of the
circuit breakers should be periodically felt for "hot spots". If abnormally hot
spots are detected, a licensed electrician should be contacted to
investigate and make corrections. Make sure the service entrance cable
(SEC) has no tree branches touching it. Remove them if necessary. The
service entrance cable is attached to the service head. Make sure the
service head is still properly secured to the side of the house. If not,
resecure it. Your electrical panels are safety devices. Occasionally you
may need to get into it quickly to turn off a circuit breaker. Every panel
should have three feet of clear space in front of it at all times. (This is
actually a code requirement). Find another place to store those items!
Electrical
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