ASK CONFIGURING POPUP IN ELECTRIC SUBNET LINE

[RomuldKiobya]

I got bit challenge to use two attributes in subnet line; Shape length that is meters and Circuit length that is feet. I decide to create Arcade expression by configure popup on subnet line. The problem is which is correct planar measurement or Geodetic Measurement? 

Planar 

Length($feature, 'kilometers');

or 

Geodetic

LengthGeodetic(line, "kilometers");

Review attached document: What I see shape length and planar are similar.

[RobertKrisher]

From the online help page discussing geodetic length versus planar length: "Geodesic distance always produces a more accurate result and is the recommended method, unless speed is more important than accuracy." That page includes a good breakdown of why it is considered to be more accurate and given that you're using this calculation in a popup for a single feature, the performance consideration isn't a concern.