I've had knob and tube (AKA post and spool) wiring kill FHA loans in the past - if the insulation over the wires has been breached, it can be regarded as bare wiring, which I understand to be an FHA no-no. It also has to be at least 60 amps.
Will the seller change the wiring out so that there are no potential issues?
Perhaps find an electrician that will do the work and accept payment at closing?... more