I have tried 3 x 3m samples of El Wire from Altronics and one sample from Little Bird Electronics and none are bright enough to be seen in daylight from a distance with the 3m connected to a standard battery powered inverter. They would be brighter is used as shorter lengths as mentioned in the El Wire articles and data sheets.
They are only viewable in very low level lighting. They could be suitable for costumes in low light conditions.
sparkfun has a Getting Started with Electroluminescent (EL) Wire tutorial https://learn.sparkfun.com/tutorials/getting-started-with-electroluminescent-el-wire/all
Explains that EL wire operates typically on 80 – 130 Vac. EL inverters can be a 3V battery box with inverter built in or 3V or 12V DC inverter modules.
Anatomy of EL shows how it works.
Spark Fun EL wire data sheets https://www.sparkfun.com/datasheets/Components/LED/Technical%20Information%20of%20Flexible%20Neon%20wire.pdf?_ga=2.252982665.1033070120.1588002353-1077977074.1588002353
Page 2 has technical information
Page updated 17 August 2020