Sequoia Watthour Meter
Two Wire, 120 Volts to Neutral
The Sequoia watthour meter measures the power used by a single 120 volt circuit. It is most commonly used to monitor pwer used by a single appliance. It should not be used in a room or apartment where a separate 120 volt circuit exists unless both circuits are on the same leg. Use the Yosemite meter instead in that case. The Sequoia consists of an electronics module, one current transformer (CT) and one electro-mechanical counter that display the accumulated power.
Available
Configurations
The Sequoia meters are available in a variety of configurations. Check the options
in the Part Numbering Guide at the bottom of this page for details.
Current Capabilities
Meters are rated by the maximum current that can flow through the
current transformers. Generally speaking, the meter should be
rated at or above the rating of the breaker that will protect the
circuit to be measured. Meters using solid-core CTs are
available in 20, 100 and 200 amp versions. Meters using
split-core CTs are available in 200, 500, 750, 1000 and 1500 amp
versions.
Resolution
Sequoia meters normally come with a resolution of 1.0 kilowatt hours (KWH). They
may also be ordered with a resolution of 0.1 KWH or 0.01 KWH. The California approved meter has no test position and always runs
in 0.01 kwh resolution.
Automatic Meter Reading (AMR)
In addition to stand-alone meters that must be manually read, the
meter is available with the following AMR options.
50ms Pulse - An optically isolated output that
closes for 50ms then opens every time the counter advances. These meters are
frequently used with radio data collection systems in apartment buildings.
Dedicated Twisted Pair - A local meter network
that communicates over a twisted pair of wires. Any number of
meters can be connected to an RS-232 interface. The RS-232
interface can be connected directly to a Windows compatible computer,
to a telephone modem, or to a TCP/IP interface module. You can
use the free Microsoft Access application to read the meters or write
your own custom application. See the
documentation section for more info.
Power
Line Carrier - This system is the same as the Dedicated
Twisted Pair except that communication is via the power line instead of
separate wires. Because of interference from nearby ground fault
interrupters and switching power supplies, this system works best in
marinas.
Enclosures
The Sequoia meter is available in a variety of enclosures, either for
a single meter or multiple meters. See the enclosures page for
more info.
OEM Versions
The Sequoia meter is also available in an OEM version so that it can
be installed in a third party NEMA enclosure. This is usefull
when the meters are to be installed in power pedestals in a marina or
RV park. A stainless steel mounting plate is available for
mounting the display counters in the enclosure.
Accuracy and Safety Certifications
Davidge Controls certifies that all our watthour meters meet or exceed
the accuracy standards of ANSI C12.1(2001), the national standard for
watthour meters that applies to all the utility companies in the
country.
The California Division of
Measurement Standards has tested the 100 and 200 amp versions of the Sequoia meter and
approved them for use in revenue metering within the state. Each meter must be
tested and sealed by the local Weights & Measures office. Be sure to read about the
California regulations.
All models of the Sequoia meter
have been tested and certified by CSA International as recognized components. They were tested against the
UL/CSA/IEC 61010-1 standard and carry the CSA mark indicating approval for both the United States and Canada.
All the NEMA4X enclosures with Sequoia meters and solid core CTs installed carry the CSA mark
that is equivalent to a UL Listed mark.
| 
