eGauge Installation Examples

Wiring diagrams and basic configuration examples for installing the eGauge on different types of electrical systems.

Submetering
Standard split-phase backfed
Direct-feed Solar
Three phase 120/208 or 277/480 Wye w/ single-phase inverter
Monitoring 480V and 600V delta systems
120V or 240V Three-Phase Delta
Three-phase High-leg delta
Monitoring multiple services with one eGauge meter
Subpanels
Monitoring 347/600V Services
Appliances
3-Phase Inverter

Submetering

The EG4xxx series meters are capable of monitoring up to 7 single-phase units (EG4015) or 15 single-phase units (EG4030) with a single meter. Single-phase units require 2 CTs each, one for each phase.

Please visit egauge.net/start for an overview of the physical installation and configuration process.

Example Wiring Diagram

Below is an example diagram of an EG4015 measuring 7 single-phase units on a distribution panel.

Ensure the meter's L1, L2, and L3 breakers are the same phases as the panels L1, L2, and L3 phases, or a phase-mixup will occur and recorded data will be incorrect. See this article for more information on phase checking.

The meter in the diagram shown below does not reflect the physical layout or dimensions of the eGauge meter.

Panel layout and installation will vary. The meter must be configured in software to match the physical installation before any data will be recorded.

A diagram showing the CT connections for the last 3 units from above may be found here.

Example Configuration

Sensors (CTs)

In most submetering installations the same model CT will be used on all breakers. In this example, all CTs are set as 100A 20mm AccuCTs. If using CTid CTs, please click the blue CTid button to configure CTid sensors.

Registers

Registers define the data points the Gauge meter records. Each power calculation consists of a sensor input (S1, S2, S3...) that has the CT, and the voltage phase it is on (L1, L2, L3). Since each single-phase unit uses 2 CTs, there are 2 power calculations in each register added together to define the total usage of that unit.

Note, while the phasing pattern for units is typically staggered as L1 and L2, then L3 and L1, then L2 and L3, and so on, in the above example this changes with Unit 5 because the breakers for Unit 5, 6, and 7 begin on the right-hand side of the panel.

Standard split-phase backfed

Basic installation measuring power coming from a power utility (grid) and from a single-phase solar-system inverter

Registers:

Notes:

With a single-phase inverter, the current flowing at any given instant on leg L2 is the negative of the current flowing on leg L1. Hence, rather than using 2 CTs on the inverter, simply multiply the negated value of CT3 with L2 to calculate the power on that leg.
The totaling rules indicate that total usage (consumption) is calculated as the sum of the power reported for register Grid and, the positive-only register Solar+. If the power reported for Solar is negative (indicating that the inverter is consuming power, e.g., during the night), then total usage is simply equal to the power reported for register Grid. It would be (slightly) wrong to define the Usage totaling rule as Grid + Solar because in this case, the inverter’s consumption would be canceled out of the usage, giving a lower than real consumption figure.

Direct-feed Solar

Same as Standard Split-Phase installation, except that the inverter feeds directly into the power utility’s grid. That is, the Solar CT is closer to the utility than the Grid CTs. This situation often arises when solar power is delivered via a line-side tap.

Registers:

Notes:

The only difference compared to the standard installation is that Solar+ was replaced by Solar- in the totaling rule for Usage. This is because the Grid CTs already capture total consumption, including any power coming from the solar system. The only exception is that when the inverter is consuming power (e.g., at night), that consumption is not captured by the Grid CTs. Adding Solar- corrects that because it will be equal to the amount of power consumed by the inverter, or zero when the inverter is producing power.

Three phase 120/208 or 277/480 Wye w/ single-phase inverter

Standard three-phase installation measuring power coming from a power utility (grid) and from a single-phase solar-system inverter. The color coding shows 120/208V, but applies to 277/480V as well. This diagram is for a Wye system with a neutral. Refer to delta diagrams for systems without neutral.

Registers:

Notes:

Three-phase installations are set up the same as split-phase systems, except that a third voltage-tap (L3) and a third Grid CT is required to measure power flow on phase 3.
With multiple inverters, add one Solar CT per inverter and define a separate register for each inverter (e.g., Solar 1 and Solar 2). Adjust the register definition according to the CT that is measuring the current and the phases that the inverter feeds onto. For example, CT5 measuring current onto L2 and also feeding onto L3: Solar 2 = S5L2 + -S5L3.
If there are more than three single-phase inverters, it is more economical to measure the total solar output with one CT per phase.

Monitoring 480V and 600V delta systems

Never attempt to connect the eGauge directly to a 480V delta or 600V delta service using the "Lx" and "N" terminals.
Connecting an eGauge meter directly to a 480V delta or 600V delta service will destroy the meter. This is not covered under warranty.
The eGauge requires a connection to the "N" terminal, failing to connect a proper "N" can result in device damage.

The eGauge is capable of directly measuring voltages up to 277V L-N (480V L-L). In the case of a delta system with no neutral, the maximum phase-to-phase voltage is 277V as the "N" terminal of the meter has one of the line voltages connected.

A 480V or 600V delta without a neutral may be monitored by the eGauge using EV1000 High Voltage Sensors.

The below diagram shows a 480V delta system. 600V delta systems may be measured in an identical manner.

EV1000 high voltage sensors are CTid-compatible. See this article for instructions on configuring CTid-compatible sensors.

The register configuration for the example shown above is simply S1xS4 + S2xS5. Note that your configuration may differ depending on which ports are used.

Proper CT/phase pairing is required for accurate readings.

Notes:

The eGauge is a Blondel Compliant meter and will measure accurately the total load of a three-wire three-phase service using two CTs when correctly installed as outlined in this document.

This method of eGauge installation employs the Two-Wattmeter Method of power measurement which is based on Blondel's Theorem. Blondel's Theorem essentially states that you need one less CT than the number of current carrying conductors in your service to accurately meter the total load of the service. Further research on these topics, if needed is left to the reader.

When completing an installation of this type it's particularly important to adhere to the wiring diagram included in this document. CT orientation must be consistent and phase verification should always be performed to ensure that there is no phase mismatch between CTs and their respective Line voltages.

120V or 240V Three-Phase Delta

Three-phase delta installation measuring power coming from a power utility (grid). The color diagram below shows a 208V delta, but this also applies to a 120V delta or 240V delta.

Registers:

Notes:

CAUTION: Since there is no neutral and none of the phases may be grounded, all conductive/metallic parts, including CT-plug screws and CT wiring should be considered live and hazardous!
If one of the phases is grounded, wire that phase to the Neutral (N) pin on the eGauge.
The eGauge inputs can measure up to 277V L-N terminal. A 600V delta must be measured the same way as a 480V Delta.
The eGauge is a Blondel Compliant meter and will measure accurately the total load of a three-wire three-phase service using two CTs when correctly installed as outlined in this document.

This method of eGauge installation employs the Two-Wattmeter Method of power measurement which is based on Blondel's Theorem. Blondel's Theorem essentially states that you need one less CT than the number of current carrying conductors in your service to accurately meter the total load of the service. Further research on these topics, if needed is left to the reader.

When completing an installation of this type it's particularly important to adhere to the wiring diagram included in this document. CT orientation must be consistent and phase verification should always be performed to ensure that there is no phase mismatch between CTs and their respective Line voltages.

Three-phase High-leg delta

Three-phase high-leg delta installation measuring power coming from a power utility (grid).

Registers:

Notes:

Wiring and configuration is identical to a standard three-phase site. The only difference is in the voltages measured on L1, L2, and L3: – L1 and L3 are 120Vac to neutral. – L2 is 208Vac to neutral.
It does not matter whether the high-leg is wired to L1, L2, or L3, as long as all three phases are measured.

Monitoring multiple services with one eGauge meter

Overview

It's common to find sites with large stepdown transformers (e.g. to convert a 277/480V service to 120/208V for lighting or receptacle loads). To measure any AC load, the eGauge requires a combination of voltage references (Lx voltage terminals) and amperage references (CTs). It's not possible to measure loads on both the primary and secondary side of a transformer by simply scaling the voltage reference from either the primary or secondary side, because large transformers typically introduce an unknown and dynamic (varying in a non-linear relationship based on load profile) degree of phase shift between the primary and secondary side of the transformer. Until recently, the only option to accurately measure power in this scenario was to either use multiple eGauge meters (one with voltage references tapped on the secondary side of the transformer and one with voltage references tapped on the primary side of the transformer).

Using the ESH044 Sensor Hub and at least one EV1000 High Voltage Sensor (the number required will depend on the service type), it is possible to obtain voltage references from multiple services simultaneously. Note that each EV1000 sensor uses a port on the eGauge, so there are still limitations (any combination of CTs and EV1000 sensors, up to 15 or 30 depending on the eGauge meter model). An ESH044 Sensor Hub must be used - one sensor hub can support any combination of EV1000 sensors and CTs (up to four total devices per hub).

This guide only applies to EG4xxx meters. Older EG30xx and eGauge2 meters do not support the EV1000.

Installation Considerations

Typically, there are a few general rules to follow when monitoring multiple services:

1. The service with the lowest voltage should be connected directly to the eGauge, and the higher voltage service(s) should be monitored with the EV1000s. The eGauge can support a phase to neutral voltage of 277Vrms, while the EV1000 can support a voltage of up to 707Vac/1000Vdc, meaning the EV1000 is much more flexible than the meter itself.

2. Sensor Hubs must be powered. Up to 2 hubs can be powered directly from the eGauge via the USB ports on the meter. For installations where more hubs are required or the USB ports are in use (e.g., for Modbus RTU communication) the hubs can be powered directly from a generic 5Vdc power supply or a USB hub may be used.

3. All hardware must be installed in a suitably rated enclosure. eGauge Systems offers several powered enclosure kits which are suitable for this purpose. Most kits feature DIN rails (for mounting the eGauge meter and EV1000s securely) along with a powered receptacle and optional stepdown transformer (which can be used to power the 5Vdc supply for the sensor hubs and/or other supporting hardware).

Examples

The following are general examples which may be useful for planning a specific installation. Note that these examples may omit certain details (for example, not all ports are shown on the eGauge meter). These are intended to serve as guidelines only - always consult local code requirements when planning an installation.

Hardware appearance in the following diagrams may not reflect the actual size or layout of actual hardware. Refer to the product pages for actual measurements.

Configuration examples are correct for the diagram shown. Note that it is essential to associate CTs with the correct phase, and failure to do so will result in incorrect readings. Correct phasing can only be guaranteed using a multimeter to verify phasing.

277/480V Wye and 120/208V Wye

In the following example, the eGauge is monitoring two loads - one on a 120/208V service, and one on a 277/480V service. Note that the neutral to loads A and B are not shown.

The meter configuration would be set as follows (note that the CT selection is filler - use the correct CTs for the actual installation):

480V Delta and 208V Delta

In the following example, the eGauge is monitoring two loads - one on a 208V Delta service, and one on a 480V Delta service. Since no neutral is present, one phase on each service is effectively treated as a neutral - for the 208V service, C phase is connected to the N terminal, and for the 480V service, C phase is connected to the negative (-) terminals on the EV1000s.

In this configuration, only two CTs are required - one on each phase which is not connected to the N or (-) terminal.

480V delta services cannot be connected directly to the eGauge! Doing so will damage or destroy the meter. EV1000 sensors or stepdown transformers must be used to monitor a 480V delta service.

The meter configuration would be set as follows (note that the CT selection is filler - use the correct CTs for the actual installation). Again, for delta services only two CTs per three phase load are required:

Subpanels

This example illustrates how to measure subpanels.

Registers:

Notes:

It does not matter which subpanel the meter obtains voltage from, but care must be taken to identify correct phasing. It is possible for phases to be reversed or inconsistent between panels.

Monitoring 347/600V Services

Overview

The 347/600Vac wye service (347V phase to neutral, 600V phase to phase) is rarely seen in the USA, although it's quite common in Canada. As the eGauge is only rated for 277Vac from phase to neutral (480V phase to phase), it traditionally could not be used to monitor such a service. However, with the introduction of the EV1000 High Voltage sensor, it's now possible to monitor these services directly, instead of using large and potentially inaccurate stepdown transformers.

To monitor a 347/600Vac service, the user will need one ESH044 Sensor Hub and three EV1000 High Voltage Sensors. An additional power supply is also required to power the eGauge (our standard 120Vac/12Vdc power supply can be used for this purpose if the barrel jack is removed).

This guide only applies to EG4xxx meters. Older EG30xx and eGauge2 meters do not support the EV1000.

Installation Considerations

1. All hardware must be installed in a suitably rated enclosure. eGauge Systems offers several powered enclosure kits which are suitable for this purpose. Most kits feature DIN rails (for mounting the eGauge meter and EV1000s securely) along with a powered receptacle and optional stepdown transformer (which can be used to power the 5Vdc supply for the sensor hubs and/or other supporting hardware).

3. The eGauge must have a separate power source in this configuration. This can either be an AC power supply connected to the L1 and N terminals providing 120Vac - 277Vac or a DC power supply connected to the Ldc terminal providing 12-60Vdc. Note that correct polarity is required when using a DC power supply.

Examples

Hardware appearance in the following diagrams may not reflect the actual size or layout of actual hardware. Refer to the product pages for actual measurements.

347/600V Wye

In the following example, the eGauge is monitoring a single load on a 347/600V panel. Note that the neutral connection to the load is not shown. The eGauge can be powered via AC or DC - both options are shown, but only one is required.

The meter configuration would be set as follows (note that the CT selection is filler - use the correct CTs for the actual installation):

Appliances

This example illustrates how to configure 120Vac (single pole) and 240Vac (two pole) appliances.

Registers:

Notes:

Registers defined for appliances do not appear in the totaling rules. Just defining the registers will make them appear in the appropriate places (e.g., in the legend of the dashboard graph).
A single CT is sufficient both for 120Vac and pure 240Vac appliances. 240Vac appliances with asymmetric currents on the two legs (i.e., with a non-zero current on Neutral) require separate CTs per leg/phase.

3-Phase Inverter

Standard three-phase installation measuring power coming from a power utility (grid) and from a three phase solar-system inverter. The color coding shows 120/208V, but applies to 277/480V as well. This diagram is for a Wye system with a neutral. Refer to delta diagrams for systems without neutral.

Registers

Totals and Virtual Registers

Notes

Three-phase installations are set up the same as split-phase systems, except that a third voltage-tap
(L3) and a third Grid CT is required to measure power flow on phase 3.
Three-phase inverters require a CT on each phase. Sometimes during low production they will not
output evenly on all 3 legs, and during standby they do not often draw the same amount of current on
each leg. Further, in standby, they may output power on certain legs and draw power on others, which
can lead to seeing erroneous overnight generation if a single CT is used.
If the solar is a line-side tap rather than back-fed, the Usage register should use Solar- rather than
Solar+. See configuration example 3.2, Direct-Feed Solar, for more information.