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CT Types/Rules
  1. CT Types
  2. CT Connection & Monitoring Rules

 

The ECM-1240 uses two basic type of current transformers (CT):

Split-Core
Solid-Core (Donut Style)

The main difference between the two is:

SPLIT-CORE installation does not require the load conductor to be disconnected.

SOLID-CORE installation requires the load conductor to be disconnected in order to "thread" through the center of the CT.

CT installation inside the electrical panel must be done by a qualified individual or electrician. This individual must be knowledgeable and obey all safety procedures and local electrical code. See users manual for more safety information.

Make sure your service is not 3-phase or powered from two phases of a 3-phase source. The ECM-1240 is designed for 120V/240V split-phase systems only.

 

CT Connection And Monitoring Rules:

CT Model

Connection And Monitoring Rules

Micro-40 (Specs)

The Micro-40 CT is used primarily for panel circuits up to 40A. If aluminum wiring is used, the limit for this CT may be 20A due to the larger diameter/A of aluminum.

RULES
Up to 5 Micro-40 CTs per channel as long as the total amperage of all CTs does not exceed 80A.
Cannot be combined with other CT models when connected to a given channel.
Mostly used with AUX channels but may be used with CH1 or CH2.
ADVANTAGE
Low Cost
Extremely small size uses minimal panel space.
More than two CTmay be used on a given channel

DISADVANTAGE
Lower accuracy
Installation requires turning the power off and disconnection of conductor to allow threading the conductor through the center of the CT.

 

Micro-80 (Specs)

The Micro-80 CT is used primarily for panel circuits up to 80A.

RULES
Up to 5 Micro-80 CTs per channel as long as the total amperage of all CTs does not exceed 80A. The maximum amperage may be extended to 160A using a special configuration.
Cannot be combined with other CT models when connected to a given channel.
Mostly used with AUX channels but may be used with CH1 or CH2.
ADVANTAGE
Low Cost
Small size uses minimal panel space.
More than two CTmay be used on a given channel

DISADVANTAGE
Lower accuracy
Installation requires turning the power off and disconnection of conductor to allow threading the conductor through the center of the CT.

 

Micro-100 (Specs)

The Micro-100 CT is typically used for larger panel circuits or sub-panels up to 100A.

RULES
Up to 2 Micro-100 CTs per channel as long as the total amperage of all CTs does not exceed 160A for AUX channels, 200A for CH1 or CH2
Four Micro-100 CTs may be used on CH1 or CH2 providing as special configuration is used.
 
ADVANTAGE
Low Cost
Small size uses little panel space.
High Accuracy

DISADVANTAGE
Installation requires turning the power off and disconnection of conductor to allow threading the conductor through the center of the CT.
 

 

SPLIT-60 (Specs)

The SPLIT-60 CT is usually used for large panel circuits where it is preferable not to disconnect the circuit breaker conductor.

RULES
Can only be used on CH1 or CH2.
Only one or two SPLIT-60 CTs per channel.
ADVANTAGE
Easy to install. No wire disconnection required
High accuracy.
DISADVANTAGE

More expensive than Donut style CTs
Requires more space than donut CTs
Cannot be used with the AUX channels

 

SPLIT-100 (Specs)

The SPLIT-100 CT is commonly used for monitoring 100A main panels or sub-panels.

RULES
Can only be used on CH1 or CH2.
Only one or two SPLIT-100 CTs per channel.
ADVANTAGE
Easy to install. No wire disconnection required
High accuracy.
DISADVANTAGE

More expensive than Donut style CTs
Requires more space than donut CTs
Cannot be used with the AUX channels

SPLIT-200 (Specs)

The SPLIT-200 CT is commonly used for monitoring 200A main panels.

RULES
Can only be used on CH1 or CH2.
Only one or two SPLIT-200 CTs per channel.
ADVANTAGE
Easy to install. No wire disconnection required
High accuracy.
DISADVANTAGE

More expensive than Donut style CTs
Requires more space than donut CTs
Cannot be used with the AUX channels

SPLIT-400 (Specs)

The SPLIT-400 CT is used for monitoring 400A main panels.

RULES
Can only be used on CH1 or CH2.
Only one or two SPLIT-100 CTs per channel.
ADVANTAGE
Easy to install. No wire disconnection required
High accuracy.
DISADVANTAGE

More expensive than other CTs
Cannot be used with the AUX channels

SPLIT-170 (Specs)

The SPLIT-170 CT is used in situations where the main panel uses rectangular buss bars instead of typical round conductors. (See example picture). The rectangular shape of this CT accomodates the buss bar where the SPLIT-200 CT would not.

(enlarge)

RULES
Can only be used on CH1 or CH2.
Only one or two SPLIT-200 CTs per channel.
ADVANTAGE
Only solution for certain panels
High accuracy.
DISADVANTAGE

More expensive than Donut style CTs
Cannot be used with the AUX channels

 

TT-100 (Specs)

The TT-00 CT is commonly used for application that require a "split type" CT to be connected to an AUX channel.

RULES
No more than two per channel
Requires a burden resistor if connected to CH1 or CH2
ADVANTAGE
Easy to install. No wire disconnection required
High accuracy.
Can be used on AUX channels
DISADVANTAGE

More expensive than Donut style CTs
Requires more space than donut CTs