How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manufactured and modular homes

When is an electrical panel overcrowded with too much wiring?

Sunday, February 27, 2022

An electrical panel is overcrowded if the jumbled maze of wires makes it impossible to follow the path of a wire from the breaker to where it exits the box. The panel shown above was so jammed with wiring that we had to push the dead front firmly against the top layer of wiring to close the panel. Not good…and not safe. 

    Filling a panel with too many tandem breakers (the kind that fit two circuits into a single slot, also called duplex or half-high breakers) is the thing that most often causes an overcrowded panel. Manufacturers specify how many tandem breakers are allowed to be installed in a panel, and where they should be located, in the wiring diagram sticker on the inside of the panel door. Newer panels have a lockout device that keeps half-highs from being installed where they are not allowed. But older panels don’t have that safety feature, and there are ways that it can be overridden even in a new panel. See our articles What is the maximum number of circuit breakers allowed in an electric panel? and What is a CTL breaker? for more on this.

    Other factors for overcrowding  include an original installation that wasn’t planned to minimize running wires from one side of the box to the other, excessive lengths of wire left in panel, and not stripping the sheathing away from NM-cables once they enter the panel box. Panels that have been reconfigured by a homeowner or handyman to connect to a generator panel are another example. We wish all the electrical panels could look like the professional job at right. Many start off life like it, but get added to again and again over the years, instead of installing a subpanel—which is our usual recommendation for repairing an overpacked panel.

    The National Electrical Code [NEC 312.8(A)] does have a standard for the maximum amount of wires allowed in wiring space of a panel: they cannot occupy more than 40% of the space cross-section, and the total of wires, splices, and taps cannot exceed 75%. Unfortunately, the problem is often not so much the cross-sectional area as the organization of the wiring in the panel.

    The addition of a “plug-on neutral," which provides a neutral bus bar under the breakers, is one feature in newer panels that reduces the amount of wires in the panel. To learn more about it, go to Why are there no neutral pigtails at the AFCI and GFCI breakers in the panel? 

• • • • • • • • • • • • • • • • • • • • • • • • • • 

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

• How can I tell a main electrical panel from a subpanel?

What causes copper wires to turn green or black 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 a Dual Function Circuit Interrupter (DFCI)? 

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 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.

Water Heaters

Water Heater Age

"What Are The

Signs Of..."

Septic Tank Systems

Structure and Rooms

Plumbing Pipes

Termites, Wood Rot

& Pests



When It First

Became Code

"Should I Buy A..."

Park Model Homes


Shingle Roofs




Wind Mitigation

Roof and Attic

"Does A Home


Pool and Spa

"What Is The Difference Between..."




Concrete and

Concrete Block

Metal Roofs


Modular Homes

Rain Gutters

Mold, Lead & Other Contaminants


Older and

Historic Houses

Crawl Spaces

Mobile-Manufactured Homes

Building Permits

Life Expectancy

Clay Soil





Exterior Walls

& Structures


Common Problems

HUD-Code for

Mobile Homes

Garages and Carports

Flat (Low Slope) Roofs

Electrical Panels

Sprinkler Systems

Electrical Receptacle Outlets

4-Point Inspections

Hurricane Resistance

Frequently Asked Questions (FAQ)

Home Inspection

Heating and Air Conditioning

Building Codes

Fireplaces and Chimneys

Inspector Licensing

& Standards

Energy Efficiency

Washers and Dryers



Doors and Windows



Electrical Wiring

Click Below  

for Links

to Collections

of Blog Posts

by Subject

Plumbing Drains

and Traps


Smoke & CO Alarms

Aging in Place

Top 5 results given instantly.

Click on magnifying glass

for all search results.






Air Conditioner & Furnace Age/Size


Electrical Switches





Water Intrusion

Electrical - Old

and Obsolete


Foundation Certifications

Tiny Houses

About McGarry and Madsen



Buying a home in North/Central Florida? Check our price for a  team inspection by two FL-licensed contractors and inspectors. Over 8,500 inspections completed in 20+ years. In a hurry? We will get it done for you.

Moisture Problems

Crawl Spaces