Main Electrical Panel
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The main electrical panel can also be called
the electrical service panel or electrical distribution panel and is where
all wiring through out the home connect.
Power lines coming from your local electrical company
come in from the pole transformer to a mask on the home or they may come
in from underground routing.
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When the electrical company's wires
first arrive at your home it first goes to an electrical meter
mount, in modern times this is mounted on outside the home on the
outside wall, some older homes had this inside. The meter could be
an analog (dial type) meter or a digital, perhaps even what they
call a smart meter. |
The meter mount is a mounting terminal bridging through
the meter to the wire that connect to the main cut off inside the home.
The purpose of the electrical meter is to measure the amount of power
consumption that is utilized in the home for purposes of determining how
much your electrical bill will be.
This meter is usually mounted close to where the main
electrical wires will enter the home and inside there must be a main
electrical cut off located close to this electrical entrance.
Now quite often the main electrical cut-off for the home
is part of the main electrical distribution panel, but it can be
separated but close by as a separate entity from the panel with the
breakers or fuses in it. The purpose of the main cut-off is to shut down
electricity beyond which is before the main distribution breaker or
fuses, in other words being able to shut off the electricity to all
circuits to the entire home.
Most homes that have basements the main cut-off and
distribution panel will be located in the basement of the home.
There is code rules that require the area around the main cut-off /
distribution / electrical panel be clear of clutter, there is also rules
relating to minimum distance from water sources. The main electrical cut
off in modern homes is in the form of a main cut off breaker will
provides not only a shut down switch but over current protection rated
at whatever your electrical service is which could be 200 amps.
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Older homes had a lever or a rocker
switch to shut down power with large cartridge type main fuses. From
here the output would go to a fuse or breaker distribution panel.
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This
is a separate cut off with cartridge type main fuses and a
breaker distribution panel. |
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Common power service to home can be anywhere from 60 amps
to 200 amps, 200 amp service seems fairly common in modern homes.
Now the average homeowner is not going to be installing a
new main service panel unless the person has above average knowledge
meaning you would likely be working in the electrical field. Replacing a
main electrical service panel that also includes the main breaker cut
off would mean that you would need the utility company to help in order
to cut off the power prior (on the utility side of the main breaker cut
off) to the main breaker cut off, leave such a major job to a qualified
professional electrician.
We will now dissect a modern the electrical service /
distribution panel.
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Now
electrical panels do vary some depending on the manufacturer / type
& model.
On the
panel to the left there is two large metal bars in the center of the
panel, these are the two ungrounded conductor hot buses, you will
see metal stubs sticking up from these where breakers will clamp
over these. A circuit that uses a breaker that is only contacting
one of the hot buses will feed a 110 volt circuit, in the case of a
dual pole breaker, the breaker assembly is in contact with both hot
buses, and uses two ungrounded conductors (hots) to feed such items
as a cooking range or dryer that requires 220 volts. These two
ungrounded hot buses are the most dangerous parts to ever
accidentally come in contact with when the panel is live. Be sure to
read the article called 'electrical safety'.
Two
grounded conductor (neutral) buses can be seen to left and
right of the hot buses for the neutral wire of each circuit. Then
lastly on the outer sides a bus bar to use for the equipment
grounding conductors. |
When working with an existing panel (assuming the panel
was originally installed by a professional) it should be easy to just
look and see the correct bus bar where the grounded conductors
(neutrals) [white wires] are connected to, and where all the bare
equipment wires are going to, so if adding a new breaker put the wire
white (neutral) to the same bus bar where the other white wires
are going and the same hold true to where the bare wires are going to.
The ungrounded conductors (hots - usually red or black) attach to the
breaker itself.
Now there are specialized breaker items such as surge
protectors that require a neutral connection or ground coming to it, so
make sure you do not follow that as neutrals from circuit cables go to a
separate bus bar it should be easy to find.
Bellow is a 3 part video I found posted on you tube that
does a good explanation of the main electrical panel.
Some comments about the videos.
1. I would prefer when working in a live electrical panel
to be using better insulated screwdrivers, ones with insulated stems.
2. For greater safety - the electrical safety authority
is now recommending using only multi meters with fused leads (link will
open in new tab / window)...
http://www.esasafe.com/pdf/Multimeter_Brochure.pdf
3. In the panel that is illustrated in the videos the
mains coming in from the street are aluminium with an anti-oxidant
pasted on the connected ends / internal circuits where copper wired.
4. Although many have done work in a live main panel
carefully without wearing insulated electricians gloves, I would highly
recommend using them.
5. At one spot in the video he mentions the word positive
in regards to the hot wire, in AC (alternating current) there is no + or
- dedicated wire, AC is alternating 60 times (60 hertz) a second, some
countries use a 50 hertz AC standard. You have a ungrounded
conductor (hot) which for the United States and Canada most times is red
or black; a grounded conductor (neutral) usually white in color; and an
equipment grounding conductor which is either bare or green.
We have experts that work in the field on our forums so
please take advantage of that for further clarification and questions.
Written: March 12, 2012
Revised: June 29, 2013
Proof Read / Released: July 10, 2013
By: Donald Kerr
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