How do I know my old house wiring is safe?

Question

Its at least 50 yr old. Metal cable w/ 2 wires inside. The internal wires are wrapped in a woven cloth like material. Each wire is encased in a rubber coating. The rubber coating seems brittle to the touch.

Answer 1

OH please?! Even though it sounds bad its really not. You have armoured cable and the metal jacket is well grounded.
So dont panic. Dont lose any sleep and dont automatically call an electician or have it all replaced.
If there is any kind of short in the wire it will automatically trip the breaker or blow the fuse.
The metal Jacket on the wire constitutes a perfectly code compliant ground and is actually safer than the cloth wrapped romex with a ground wire. Which came along just after armoured cable.
The best thing to do is upgrade your service panel to breakers if it is not already. And if they are the old style 'pushmatic' breakers I would suggest you do upgrade to the latest type service panel with new breakers.

Answer 2

As a union electricain from chicago, Id say some people where wrong and right. What you have is bx. The metal covering can and probably is acting as a ground. The fact that it is cloth wiring, I would say replace it, when you have the cash to get it done. Make sure that whatever outlet that you looked at the wire, that there is no exposed copper. Use scotch33 tape and tape the wire well. Replacing the wire is probably more important than changing a panel from fuses to circuit breakers. Fuses are actually very very safe when used properly. Make sure you dont put a 20amp or 30 amp fuse in a 15 amp spot, or do the penny trick. If properly fused a fuse will protect better than a circuit breaker and protect for lifetime. Unfortuntly your cloth wiring will not. So rewire first.

Answer 3

The best way to tell is if the house is still there. The wiring you are describing is very reliable. If not disturbed, that brittle covering will last another 150 years or more. The only problem that showed up with that wiring method was with grounding. But that is nothing to concern yourself with either. We called that metal cable type BX flexible metal conduit. If your wires happen to short, you will trip a circuit breaker or blow a fuse and everything will still be ok. Rest easy. Email if you have more questions.

Be wary of taking electrical advise from untrained and unqualified people.

Answer 4

I just remodeled a house built in 1946 (completely gutted out to the wall studs). It had a lot of that old cloth-insulated wiring with some Romex installed in rooms that had been rewired a couple years before I bought the house.

Before the remodel, I noticed that the electrical system was very unstable. When I turned on the TV, the lights would dim. Light bulbs would generally last about 6 months before they blew out. And, the circuit breakers in the electrical panel would regularly trip for no obvious reason.

Since the remodel, where the entire house was rewired, I have not experienced any electrical problems. But, unless you redo the electrical system at the same time as a remodel, it would be very difficult and expensive - if it's even possible - because of the difficulty of running new wires without tearing out the drywall.

Answer 5

You're right, you have really old wiring. It's probably safe so long as there are no bare wires showing and the insulation isn't stripped back through the jacket. With only two wires though there is no ground. If I were you I'd check into having yur house rewired.

Answer 6

It is definitely a good investment to get a wiring update.
Some times old lines to the shed, attic, or basement are
really not used much. This is an area to look for savings.
I recently ran into CYC sponsors for basic repair and the
team leader put me on to the senior handicapped do good
work at very low prices. Electricians can be very top dollar
in entire areas, check with the veterans of Vietnam, I got
two exfull time electricians both in limited work retirement.
I got 6 jobs at 120 hours done at 20.00 dollars an hour.
They were expert enough to get all the parts, and updates
that were needed. Similar to your situation to rewire the
entire houses, taking about 40 hours each.

Answer 7

Robert K and John Himself have provided you with good answers, the rest....not so good. The rubber coating is probably brittle as you describe, mostly apparent in ceiling fixtures. Tape well with Scotch 33 when you run across the brittle insulation. There is nothing wrong with the 'ol BX cable in your home.

Answer 8

For it to meet code,you need a third wire ground which wasn't introduced until 1961.I would not trust cloth insulation as it can tear easily,causing fires.Your wiring predates plastic so it is 1940-1950 vintage.I would get estimates for replacement immediately.Frayed house wiring is the number one cause of house fires,especially in winter when Christmas lights and electric heaters are used.I would especially add GFCI's to the wet area's for protection from electrocution.

Answer 9

Have a home inspector check your home out. Codes change with the economy. Once, aluminum wire was used to cut cost. Now to replace costs ten fold. Fuses have been replaced with breakers and Ground Fault Interrupts are now required in wet conditions.

Answer 10

If it's that old I would not feel safe until it was inspected or replaced.
Peace of mind will let you sleep better.