[Q] Backing up w/ TWRP ... wiping sd card question

I am use to working with phones that have a removable SD-Card. Since our Note 5 does not have a micro card slot, I have a question.

Using TWRP, when I do a nandroid backup it obviously backs up to the phone SD. If I do a FULL wipe via TWRP (system / data / user / cache) wont it also delete my TWRP backup file located in ..mnt/sdcard/TWRP ?? normally I would backup to the removable SD Card and just format / wipe the internal memory and safely have my nandroid backup on the removable stick for future recovery.

Please advise ??

Also what about a full DATA wipe (/media/data/..) is that safe ?

Thanks