Why is an undersized wire between a circuit breaker and a whole-house surge protector device acceptable?

Wednesday, December 26, 2018

The wires connected to each breaker in an electric panel should be the right size, and specifically not too small, for the rating of the breaker. Undersize wiring may overheat when too much current is flowing through it and start a fire before the mismatched breaker trips. It’s one of the things we check when opening a panel during an inspection. A 50-amp breaker, for example, should be connected to a #6 wire if it’s copper.

   But, according to manufacturers, standard rules don’t apply when the breaker is connected to a whole-house surge protector because the wires do not actually carry a load current. Instead, they support only short-duration currents associated with a transient surge event. So, for example, a #14 wire, which would normally only be acceptable for a 15-amp breaker, can be used for connecting the 50-amp breaker to a Type 2 surge protector. 

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Here’s links to a collection of our other blog posts about ELECTRICAL WIRING:

Which house appliances need a dedicated electrical circuit?

Can a short circuit cause a high electric bill?

What is the maximum spacing requirement for securing NM-cable (nonmetallic-sheathed cable)?

Is it alright to just put wire nuts on the end of unused or abandoned NM-cable or wiring?

What causes copper wires to turn green or black in an electric panel?  

What are typical aluminum service entrance wire/cable sizes for the electrical service to a house?

Why is it unsafe to bond neutral and ground wiring at subpanels?

Should I get a lightning rod system to protect my house?

Why is a strain relief clamp necessary for the cord connection to some electric appliances?  

Does a wire nut connection need to be wrapped with electrical tape?

What is the minimum clearance of overhead electric service drop wires above a house roof?

What are the requirements for NM-cables entering an electric panel box?

What is the color code for NM cable (Romex®) sheathing?

Why is undersize electric wiring in a house dangerous? 

What causes flickering or blinking lights in a house?

Why are old electrical components not always "grandfathered" as acceptable by home inspectors?

How can I find out the size of the electric service to a house?

Can old electrical wiring go bad inside a wall? 

What is an open electrical splice?

What are the most common electrical defects found in a home inspection? 

What is the life expectancy of electrical wiring in a house? 

What is an "open junction box"? 

How dangerous is old electrical wiring? 

What is a ground wire? 

I heard that aluminum wiring is bad. How do you check for aluminum wiring?  

    Visit our ELECTRICAL page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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