How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manfuactured and modular homes

What is a missing twistout at an electric panel?

Monday, September 3, 2018

The metal plate screwed to the front of an electric panel is called a deadfront. While you may be used to seeing it in your home with circuit breakers arranged in two rows protruding through an opening in the plate, the panel is manufactured as a solid plate that is perforated with rectangular shapes called “twistouts” that can be literally twisted and snapped out individually by an electrician, who removes only as many twistouts as there are circuit breakers to be installed in the panel, so that when the installation is complete there are no openings in the front of the panel that allow any of the live wire connections—or the metal bus bars that run down the back of panel box and connect the breakers to the electric service—to be touched when the panel door is opened.

   If too many twistouts are removed or a breaker is later removed from the panel, there are plastic blanks, available at any hardware store, that can be snapped into the opening created in the deadfront. The two arrows in the photo above point to missing twistouts that have exposed the “live” interior components of the panel. Directly below the left missing twistout is a plastic blank that has been installed to cover opening where a circuit breaker has been removed. 

   Because a missing twistout allows the possibility of electric shock, it is a safety defect that a home inspector will call out in an inspection report. The openings in the sides and back of a panel box, called knockouts, are also required to be sealed if not used. See our blog post What is a "missing knockout" or "open knockout" in an electric panel box? Why is it a problem? for more on this. 

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Here’s links to a collection of our other blog posts about ELECTRIC PANELS:

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

What is the maximum number of circuit breakers allowed in an electric panel?

When should a corroded or damaged electric panel cabinet or disconnect box be replaced? 

What is a tandem circuit breaker? 

When did arc fault circuit interrupter (AFCI) breakers first become required?

Can an electric panel be located in a closet? 

Can an electric panel be located in a bathroom? 

Can you add circuit breakers by different manufacturers to an electric panel if they fit?

My circuit breaker won't reset. What's wrong?  

What is a split bus electric panel?

How do I identify a combination AFCI (CAFCI) circuit breaker? 

What does a circuit breaker with a yellow or white test button indicate? 

What is the maximum gap allowed between the front of a recessed electric panel box and the wall surface surrounding it? 

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

Why is a fuse box/panel an insurance problem for homebuyers? 

Why is bundled wiring in an electric panel a defect?

What is the difference between GFCI and AFCI circuit breakers? 

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

What happens when you press the "TEST" button on a circuit breaker in an electric panel?

What is a Dual Function Circuit Interrupter (DFCI)? 

What is the difference between a Combination Arc Fault Circuit Interrupter (CAFCI) and an Arc Fault Circuit Interrupter (AFCI) circuit breaker?  

What is the difference between "grounded" and "grounding" electrical conductors? 

What does it mean when a wire is "overstripped" at a circuit breaker?

Why is an old fuse panel dangerous?  

Who is the manufacturer of those "bad" electric panels?

Why is the circuit breaker stuck in the middle? 

What is a double tap at a circuit breaker?

What is the right electric wire size for a circuit breaker in an electric panel?

What is the life expectancy of a circuit breaker? 

My circuit breaker won't reset. What's wrong? 

Why do some breakers in my electric panel have a "TEST" button on them?

What is the right size electric panel for a house? 

• What do I need to know about buying a whole house surge protector? 

What is the maximum allowed height of a circuit breaker (OCPD) above the floor?

• What is the maximum height you can mount an electric panel above the floor? 

• What is the code required clearance in front of an electric panel?

What is the main bonding jumper and where do it find it in an electric panel? 

   Visit our ELECTRIC PANELS 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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