Video: How to properly short a CT shorting block?


28 September 2021

Product Line
3090 SCCT
Current Transformer Shorting Block

Hardware installation/modification

*Warning: Installation and maintenance of this device should only be performed by qualified, competent personnel that have appropriate training and experience with high voltage and current devices. Failure to follow the instructions / warnings in the Meter Installation Guide can result in permanent damage to the meter, severe injury or death. 

CT shorting blocks are used to create an intermediate contact point between the meter and load where it is safe to perform wiring alterations. CT shorting blocks are wired such that the negative leads of the current transformers are connected to the same node and tied to ground.

Four or Six pole shorting blocks can be used in applications with up to three current transformers as shown in the diagram below, which allows each current transformer lead to have an individual contact point. 

In order to safely modify the current transformer wiring at the meter or metering side of the CT shorting block, the positive leads of the current transformers must also be shorted out to the CT shorting strip using the additional screws which are usually found on the corners of the shorting block.

Once the current transformers are properly shorted using the CT shorting block, it is safe to make wiring modifications on the meter side of the shorting block.

Once the intended wiring modifications have been completed, you will need to remove the shorting screws from the positive CT lead terminals in order to return the meter to proper operation.

Be aware that incorrect alterations can result in arc flash.

For further information and documentation regarding Schneider part numbers for shorting blocks, click here