Try this if you want to write a UTF file with no BOM: using-powershell-to-write-a-file-in-utf-8-without-the-bom
$MyRawString = Get-Content -Raw c:\junk\bom.txt
$Utf8NoBomEncoding = New-Object System.Text.UTF8Encoding $False
[System.IO.File]::WriteAllLines("c:\junk\NewNoBOM.txt", $MyRawString, $Utf8NoBomEncoding)
I used the same content as MotoX80:45436-bom.txt
I used a very handy tool (HxD: hxd) to examine the two files and exported the results from HxD as "Editor view". The BOM isn't present on the file EXPORT-NewNoBOM.
45494-export-bom.txt
45330-export-newnobom.txt