Thread: how to Find and Replace using different excel sheet?

Assuming both workbooks are open, this should do it for updating column C on that target sheet:

Option Explicit

Sub MassFindReplace()
Dim vSRC As Range
Dim v As Range

With Workbooks("Light Naming.xls").Sheets("Sheet1")
    .Range("A:B").Sort Key1:=.Range("A1"), Order1:=xlDescending, Header:=xlNo, _
        OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom, _
        DataOption1:=xlSortTextAsNumbers
    
    Set vSRC = .Range("A:A").SpecialCells(xlConstants)
End With

Application.ScreenUpdating = False
With Workbooks("Electrical Master-Template.xlsx").Sheets("IL electrical-SB Map")
    For Each v In vSRC
        .Range("C:C").Replace v, v.Offset(, 1), xlPart
    Next v
End With
Application.ScreenUpdating = True

End Sub

It's important that the data being searched for is sorted Descending before you do this, else a search for WS-1 will occur before the search for WS-10 and have already made an incorrect change to the sheet.