Should we change the copper wire?

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Shervan360
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Hello,

Suppose we have a building that is 30 years old. It is being overhauled.
Do the copper wires need to be replaced? Do electrical wires have a useful life?

In our country, electricians don't have certificates and they learn through experience. They don't have technical and theory information. Most of them don't have even passed one unit of electrical course! So I need to get technical and correct information.

Thank you
 
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Shervan360 said:
Do the copper wires need to be replaced? Do electrical wires have a useful life?
The life of the wiring is probably determined by the quality of the insulation. If it was wired to a national code in the last 30 years, then it should still be safe and functional.

We do not know who wired it, so you will need to get it assessed, to identify if it was wired to the standard code.
 
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If the wires were installed well, they will last essentially forever. They must have been protected from water (or other corrosives), abrasion, and excessive mechanical stress (pulling/bending). Any damage is most likely near the terminations and can be inspected. Step 1: inspection, step 2: fix installation issues, step3: replace branches that have been damaged.

There is an assumption that reasonably good materials were used. This is nearly guaranteed in 1st world economies 30 years ago. Still, we can't say what the original builder actually did.

PS: also check for the correct sizing (ampacity). People tend to connect more stuff as time goes on. This isn't so much about the wires as the distribution system. Are those wires still correct for the actual usage?
 
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Apart from all above (inspection and check of wires) I would mind (maybe: just replace without much thinking) the connections too. Most of the cases that's where you can catch the gremlins.
 
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Half the wiring, switches, and outlets in my house are more than 75 years old.
 
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Likewise, the wiring in my over 100 year old house, for lights and the original power outlet for a refrigerator, are all original, circa 1945. They have two solid copper conductors, each helical wound with cotton thread twice, left and right, inside a grounded lead sheath. I don't disturb it, and it doesn't disturb me.
 
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Here in the UK, you can get an EICR - electrical installation condition report. This is a series of dead and live tests on the supply and individual circuits.

It seems that the main ‘aging’ of the setup is not so much the copper wires themselves, but:

1. Dodgy wiring alterations by previous homeowners, eg borrowed neutrals, missing earths, broken ring mains.
2. Loosening of screwed terminals, leading to poor connections and heat.

Some very old wiring was insulated with VIR - vulcanised India rubber, which by this age just cracks and falls off.

If your electricians are not up to scratch, you could get a simple socket tester to give an idea of polarity and earth presence. Some of them roughly test what we call Zs, the supply earth fault loop impedance. This is a measure of the integrity of the earth path, should a fault occur.

It might also be worth getting an electrician to go round the entire installation, checking all the terminal screws are tight. A torque screwdriver is ideal for this, but an experienced hand almost as good.
 
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Shervan360 said:
Hello,

Suppose we have a building that is 30 years old. It is being overhauled.
Do the copper wires need to be replaced? Do electrical wires have a useful life?

In our country, electricians don't have certificates and they learn through experience. They don't have technical and theory information. Most of them don't have even passed one unit of electrical course! So I need to get technical and correct information.

Thank you
Even if you don't have tight regulations in your counbtry, you still could have an issue with insurance. Insurance companies are not in the business of handing over money for claims without a struggle. You could save yourself a lot of grief by getting a professional electrical survey to reduce the possibility of fire. The state of the wires themselves is not the only issue; it's already been mentioned that modern electrical loads tend to be a lot higher than a few years ago.

However, thirty years is not a long time in electrical terms so a reliable electrician should be able to check your installation and allow you to rest easy. You could always acquire a copy of US or UK wiring regulations There are even some good summary publications which are easy to read. As already mentioned, a cheap socket tester could be worth buying. Your local electrician will have a posher machine which will test for Earth connection and a few other things. Also, you can have your consumer unit ('fuse box') upgraded with RCDs (names may vary) to check that you get protection from death by electric shock.
 

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