Cloth covered wire

[Rafael Floresta]

I am evaluating buying this property. It has a cloth covered wire, from the 60's. 

The wires have ground in them, and they run all three cables (hot neutral and ground) inside the same wire. They seem in great condition, and I am wondering if I should replace it since I am going to rehab the place. Code says if you are going to rehab you need to bring the wiring up to code. 

I am interested to know if the code is specific to have the NM wire cover being a plastic/pvc cover, and if those wires from the 60's have the right gauge by code.

[Jon Holdman]

The best answer is your building department.  But its unlikely you will be required to replace these.  I still have some of these in my house and have done work with inspections and have not had any issue with these.  Its going to depend on what your inspectors want, though.

The correct terminology is that a "cable" consists of several "conductors".   The conductors are insulated separately, then combined together into a cable, which has an additional layer of insulation (aka "sheathing").

The cables should be marked with a gauge.  Such as "12-2" or "14-2 w/G".  The wire gauge dictates the breaker size.  For a 15 amp breaker, wire must be at least 14 gauge.  For a 20 amp circuit, at least 12 gauge.  Higher loads (range, electric furnace, ac condensor, etc.) may require larger gauges.

One issue with these older cables is the ground wire sizing.  New cables will have the ground the same gauge as the current-carrying conductors.  In these old cables it was common to have a smaller gauge wire for the ground.  Normally the ground wire doesn't carry any current.  It only carries current in the event of some fault.

Another issue is that current codes often require many more circuits than are present in an old house.  A kitchen may be wired with a single circuit, not including the range.  An update will typically need at least four - two "small appliance circuits", one for the fridge and another for the dishwasher.   Bedrooms now commonly require arc fault breakers, and bathrooms and basements require GFCIs.   All that means you very often have to upgrade the service panel.

My experience is if you work with the building department and make it clear you want to do the right thing, they will help you.  Might not be the case in your area, but its worth a shot.