How To Look At A House

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What is an electrical subpanel?

Thursday, December 9, 2021

The best way to define a subpanel is to describe what it is not. A subpanel is not a service panel (often called a main panel), which is the first panel after the electric meter and is capable of shutting off all the incoming power to it. A subpanel is downstream from the service panel and electricity flows through a circuit breaker in the service panel to get to it.

     A service panel can have multiple subpanels, each of which may be used to control power in different areas of a building or nearby buildings. And a subpanel can have other subpanels downstream from it. Also, a subpanel may have a main breaker inside that disconnects all power from it; but that  is not required, because it can be accomplished by its breaker in the service panel. And a subpanel must be wired a little differently from a service panel, with neutral wires connected to a separate bus that is not bonded with the ground wires.

    Although a subpanel might be smaller, like the one shown above, it can also be large, with dozens of circuits. Many homes today have a service panel at an outside wall, and the panel inside the house with most of the circuit breakers is a subpanel.

    To learn more about subpanels, see our articles Why is it unsafe to bond neutral and ground wiring at subpanels? and Why is there no main shut-off breaker in my electric panel? and What is the main bonding jumper and where do it find it in an electric panel? 

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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 a split bus 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 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?  

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 code required clearance in front of an electric panel?

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? 

   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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