Are there any safety implications in providing heated baselayers for employees who are working outside - I am looking at providing something like the following:

Versatile, USB-rechargeable WorkSkin heated base layer powered by REDLITHIUM USB battery technology with carbon fibre heating elements to create and distribute heat to the chest and back, with quick-heat function allowing heat to be felt up to 3 times faster in the chest and upper back heating zones. Features mid-weight construction from durable, pilling-resistant material to keep the body warm and dry whilst working, with raglan-style sleeves and seamless shoulders for improved mobility and comfort. Fully heats up in 2.5 minutes. Powered by L4 USB rechargeable REDLITHIUM battery pack. Provides excellent run time - up to 180 minutes of heat on low level

I would have a daily inspection for the wiring and battery etc and charging would be completed during office hours off the body.

Any thoughts are welcome - thank you