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Lightening and House wiring #299
01/11/01 05:27 PM
01/11/01 05:27 PM
M
Mat Aschenberg  Offline OP
Junior Member
Joined: Jan 2001
Posts: 1
Aurora,CO,USA
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?

Work Gear for Electricians and the Trades
Re: Lightening and House wiring #300
01/13/01 08:45 AM
01/13/01 08:45 AM
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,890
NY, USA
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. [Linked Image]

Re: Lightening and House wiring #301
01/13/01 04:17 PM
01/13/01 04:17 PM
D
doc  Offline
Member
Joined: Nov 2000
Posts: 123
Texas
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


MAY THE SUN SHINE ON YOUR FACE IN THE MORNING AND YOU AWAKE WITH A SMILE
Re: Lightening and House wiring #302
01/13/01 06:17 PM
01/13/01 06:17 PM
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,890
NY, USA
doc,

They also have surge protection for the panel too.

Re: Lightening and House wiring #303
01/21/01 08:05 PM
01/21/01 08:05 PM
Scott35  Offline

Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
Hi Matt and everyone else!! I am back from the Honeymoon! Had a GREAT time [Linked Image]

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."


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

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