nts
are capable of destroying sensitive electronic equipment in
commercial and industrial applications.
Transient Voltage Spikes
The most damaging voltage spikes are caused by lightning
strikes. Although lightning strikes on high voltage lines are
generally dissipated by utility transmission and arresters, a
lightning strike on a power line several miles away still has the
potential to cause extensive electrical damage. Damage to
expensive electrical equipment can be either instantaneous or
cumulative. 60
Number of Thunderstorms
A typical lightning strike consists of 25,000 amps at 30 million
volts. The following map shows the approximate mean annual
number of days with thunderstorms in the United States.

TPS
Computers and other office equipment are susceptible to the
high energy levels caused by an electrical surge, whether it is
caused by electrical equipment or lightning. Any component
between the source of the surge and ground can be damaged.
Siemens TPS transient protection system clamps these
damaging voltage spikes before they damage expensive and
sensitive equipment.
TPS 61
Installation
The TPS is bolted directly to the bus bars within the P1
panelboards. Purchased over the counter and utilizing a field
installation kit, the TPS transient voltage protection system can
easily be mounted in existing P1 lighting panelboards. LEDs
indicate that the device is working and provide voltage and
diagnostic monitoring. There is an audible alarm and test button.
Options include a surge counter and a remote monitoring
device.

TPS with LED indicatiors,
audible alarm with silence
switch, and test button.
Clamping Voltage
Clamping voltage is the amount of voltage allowed across a
surge suppression device when it is conducting a specific
current created by a surge. The following chart indicates
clamping voltage for the Siemens TPS.
Peak Current Peak Rating
Peak current rating specifies the maximum current that a
protective device can withstand from a single surge. The
Siemens TPS can withstand impulse currents as high as 80,000
amps or 160,000 amps, depending on the model. 62
Review 6
1. The maximum number of circuits available on the P1
lighting panelboards is ____________ .
2. One way to convert a P1 from top to bottom feed is to
relocate the main breaker or lug module. Another way is
to ____________ the interior.
3. The maximum voltage of an P1 panelboard is
____________ VAC.
4. The maximum integrated equipment short circuit rating
of a P2 panelboard is ____________ AIR.
5. The maximum voltage rating for a P1 panelboard is
____________ VAC.
6. The ____________ ____________ ____________ is used
to protect sensitive electrical equipment from damaging
voltage spikes. 63
P4 and P5 Panelboards
P4 and P5 power panelboards are similar in design and features,
but vary in the ratings available. P4 and P5 panelboards will
accept various circuit breakers and fusible switches. P4 will
accept branch circuit breakers up to 600 amps. The P5 will
accept branch circuit breakers up to 1200 amps. 64
Panelboard Ratings
The following information gives various P4 and P5 rating
ranges. Refer to Siemens Speedfax when ordering specific
panelboards. Branch circuit breakers vary depending on the
panelboard rating.
P4
P5
Voltage
System
Main Lug Only
Main Circuit Breaker
Main Fusible Switch
Branch Circuit Breakers
Integrated Equipment
Short Circuit Rating
600 V
600 V
400 A - 1200 A
400 A - 1200 A
800 A, 1000 A, 1200 A
400 A - 600 A
800 A, 1200 A
100 A - 200 A
All 15 A - 600 A
All 15 A - 1200 A
200,000 AIR Maximum
200,000 AIR Maximum
1
3W, 34W, 33W,
1
3W, 34W, 33W,
Dimensions
The P4 is 32 wide by 10 deep. This simplifies handling and
installation. The enclosure height varies with the type and
number of circuits required. The enclosure heights are 60, 75,
and 90. A one piece door is available which allows for locking
and flush mounting.
The P5 is 38 wide by 12.75 deep in a NEMA Type 1 enclosure.
The P5 is 38 wide by 14.25 deep in a NEMA Type 3R or
12 enclosure. The enclosure height varies with the type and
number of circuits required. The enclosure heights are 60, 75
and 90. 65
Fusible Switch
Although many panelboards use circuit breakers, it is important
to note that some panelboards, such as the P4 and P5 also use
fusible switches. Siemens branch fusible switches are available
with ampere ratings from 30 to 1200 amps.
Siemens fusible switches can be fitted with Class J, L, RK1,
RK5 or T fuses. The following illustration shows a Class R fuse
holder. 66
Clampmatic Action
Siemens Vacu-Break
®
fusible switches, through 600 A, feature
a Clampmatic
®
action. This action holds the current carrying
contact surfaces in a vise-like grip. Heat build-up due to current
is minimized. When the switch is moved to the OFF position
the movable contact snaps from between the jaws providing
a quick, clean break. Twin arcs are produced which are smaller
and extinguish quicker than a single arc produced by other
designs.
Enclosed Arc Chamber
The contacts are surrounded by an enclosed arc chamber
which absorbs much of the heat from the arching. The enclosed
chamber helps limit oxygen which aids the cooling and rapid
extinguishing of the arcs. 67
High Contact
A high contact pressure (HCP) switch is used on switches rated
Pressure Switch
for 800 A and 1200 A. The HCP switch does not use the Vacu-
Break
®
design. 68
Telephone and Equipment Panelboards
Siemens also manufactures telephone and equipment cabinets
which conform to requirements of Underwriters Laboratories,
Inc. Cabinets are 5.75 deep, 20 or 24 wide and vary in
height from 23 to 65. All telephone and equipment cabinets
are preceded by the letters TC in the catalog number. The
catalog number also reflects the cabinet height. For example,
TCS23B is a telephone and equipment cabinet that is 23 in
height. 69
Seismic Rated Panelboards
Seismic activity occurs throughout the United States and the
world. The Uniform Building Code (UBC) specifies ratings for
the United States. The following seismic zone map roughly
identifies seismic activity areas in the United States. Areas in
zones with higher numbers experience greater seismic activity
than areas in zones with lower numbers.
Siemens panelboards have undergone extensive seismic
testing in order to obtain third party certification. Siemens
panelboards will operate in zones 0, 1, 2A, and 2B with no
modification. Panelboards that require zone 3 and 4 ratings are
available with standard lead times.
UBC Seismic Zone
Product
0
1
2A
2B
3
4
S1, S2, S3
P4, P5
Standard
Optional 70
Accessories
Accessories add to the performance of a panelboard or adapts
the panelboard for specific application requirements. Various
accessories are available for Siemens panelboards.
Shunt Trip
Some accessories modify the circuit breaker. For example, it is
sometimes necessary to trip a breaker from a remote location.
If someone were to get caught in a piece of machinery, anyone
else can push a panic button tripping the breaker. One or all
critical circuit breakers may be tripped at the push of a button
from a distant control point by use of a shunt trip device. The
shunt trip may be part of the main breaker which will shut off
the entire panelboard, or part of a branch breaker. The shunt
trip device consists of a coil in series with a limit switch. When
the circuit breaker contacts are closed, the limit switch is
closed. Depressing a customer-supplied pushbutton energizes
the shunt trip coil, causing the breakers mechanical latch to
disengage the trip mechanism and opening the circuit breakers
contacts. When the circuit breakers contacts open, the limit
switch also opens, removing power from the shunt trip coil. As
with any trip, the breaker must be reset manually.
Limit Switch
Coil
Pushbutton
Customer Supply 71
The following illustration shows how an accessory such as the
shunt trip is mounted on its associated breakers.
Shunt Trip Accessory
Shunt Trip Accessory
ED Frame
Other Sentron Series
Time Clocks
Tork, Sangamo or Paragon time clocks are available as an
accessory. Time clocks are available in 1 or 2-pole, single or
double throw devices, or 3-pole, single throw. They are rated for
a maximum of 277 volts.
Tork Time Clock 72
A time clock can be used to turn a branch circuit or an entire
panelboard on and off at predetermined times. In the following
illustration, for example, a time clock connected to a panelboard
is used to turn outside lights on and off on a small commercial
building.
Storage
Time Clock
Panelboard
Meter
Retail
Lighting
Parking
Remote Control Switches
ASCO 920 switches are mechanically held, two- or three-
pole remote control switches may be used as a main circuit
disconnect device when an application calls for a switch to
daily turn blocks of lighting on and off. ASCO 920 switches
are available in 30, 60, 75, 100, 150, 200 and 225 amperes.
Siemens also has a type CLM switch (not shown) which is a
mechanically held, 20 amp, remote control unit, suitable for all
types of lighting loads. It is available in 2, 3,