Why use cable numbering?

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What is cable numbering?

A cable number is a unique identification label generally used on every control wire in a control switchboard.

The configuration of the actual number used can be in many different formats.   A common format (and the one that Metroid uses) generally uses 5 digits as follows:

1st & 2nd digits: the drawing page number
3rd & 4th digits: the line number on the drawing
5th digit: the connection number on the line

This enables an engineer or electrician to easily cross-reference a labelled cable directly back to the exact location on the electrical drawings.

For example, for the cable circled in red in the image above, an electrician would refer to page 1 of the electrical drawings, line number 6 and connection number 1 on that line on the drawing.

Why use cable numbering?

Using cable numbers to label each cable in a control panel is crucial for several reasons:

Streamlines testing & troubleshooting during board construction
When an engineer runs a functional test on a control panel after construction, if there is anything that doesn’t work as intended, the task of troubleshooting is greatly simplified by having each cable clearly identified.  A savvy engineer can even perform simple troubleshooting without having to refer to the electrical drawings.  If no cables are labelled, it makes the engineer’s job a nightmare and significantly increases the time to test and troubleshoot the panel.

Simplifies future changes
Often modifications or additions can be done some time after original construction, or if done by someone other than the original board builder.  Having every cable clearly marked makes modifications very straightforward.  If  no cables are marked, it makes the electrician’s job much more difficult and greatly increases possibilities of mistakes or functional issues.

Simplifies remote support
When an engineer is providing remote technical assistance over the phone to an onsite electrician, having all cables clearly marked greatly assists with communication and rapid troubleshooting.

Insist on cable numbers in all your control switchboards, it eliminates frustrations and wasted time for persons working with the board, now and in the future.