ECN Forum Forums General Topics of the Trade General Discussion Area Lightening and House wiring

I was told a couple of years ago that house wiring was protected from voltage surges over 6kV. Is this true?

What protects house wiring from lightening surges generated up the line, say before the 220/120 transformer?

Mat,

I would think that the Utility has got that (before the transformer) covered somehow. Does anyone know what affect the transformer has on surges going thru it? I would think that it would help to surpress the surge, but am only guessing.

I am not aware of any type of protection in the last several years we have had to replace our meter base and main panel on house 3 times .Once the surge was so great that it completely melted the meter to nothing .Oh the utility company replaced the wiring and the meter and base ,but we had to absorb new panel and wiring and referigater and 2 TV'S as they are not responsible past the meter .The only thing I know you can do is buy surger arresters for each item in your home

doc,

They also have surge protection for the panel too.

Hi Matt and everyone else!! I am back from the Honeymoon! Had a GREAT time

To answer your question quickly:

The insulation will limit the maximum potential to somewhere around 5 to 6 KV before it breaks down and allows the surge currents to flow either to ground [prefered], or between the circuit conductors [not so bad]. This creates a better path of flow for the surge currents than through the load[s], so the majority of the surge will flow through this instead of the load[s].

Since the surges are transient, there is normally a minimal amount of damage done to the insulation at that point. Only when the surges are long and continuous does the insulation become damaged and causes a short or ground fault.

So to sum it up, Thermoplastic insulations [TW, THW, THWN, THHN] and the such-like XHHW- will only withstand a potential [voltage or EMF] to a certain level before they break down. Breakdown allows the leakage of currents to an opposite polarity. This limits the surge values to a maximum of 5 to 6 KV.

Scott "S.E.T."