Maximum number of breakers in a residential panel

[SteveR]

Hello Jerry,

I'm a home inspector in Sarasota FL. I'm a FABI and NAHI member. I did an inspection in Longboat Key, FL and found 45 breakers inside a panel. I stated the max number allowed is 42 and the seller, had a licensed electrical contractor check the panel and said it was ok and did not need repairs or upgrades. (I have a pdf with the letter from the licensed electrical contractor).

The buyer is an architect who did a little research and found the max number to be 42. The buyer wants to make sure, the electrical contractor is correct and the panel is safe and meeting all present standards and not be stuck needed to install a sub-panel after closing. They also want to know when was the rule to have a max # of 42 adopted.

Thank you for your time,

SteveR
Alert Inspection Service, Inc.
Sarasota, FL

PS: I have the email exchange between the Realtor and myself and the pdf from the electrical contractor if needed.

[Jerry Peck - Codeman]

Hi Steve,

Prior to 1965 electrical panels were made to accept basically the amount of breakers which would fit into the panel - those are now known as non-CTL panels (CTL stands for Circuit Total Limiting, which means those panel had no means to limit the number of breakers in a panel).

Since 1965 electrical panels have been made with mechanical feature on the bus bars which are intended to limit the total number of breakers, i.e., the total number of circuits, and are known as CTL panels (Circuit Total Limiting which means the panels have mechanical means intended to limit the total number of circuits to that which is intended for the listing and labeling of that panel).

Many panels are not listed for even 42 circuits, they may be listed for 8 circuits, 12 circuits, 24 circuits, or 42 circuits (those are the typical normal circuit totals you will find in panels). Then, in panels which are listed for less than 42 circuits, the manufacturers will typically provide some - not many, but "some" - breaker slots which are designed to accept the special half-size single breaker, regular-size tandem or piggy-back breaker, double or twin half-size breaker all of which are single pole breakers. Some manufacturers also make a quad breaker consisting of 4 half-size breakers which results in two double pole breakers with a pairing of the two inside breakers and a pairing of the two outside breakers which have special handle ties to tie them together.

The above is done to allow adding circuits in a panel up to the maximum of 42 circuits allowed by code (pre-2008 NEC maximum of 42 circuits).

If there are more than 42 circuits in an older panel (manufactured to pre-2008 NEC listing and labeling) than someone installed those special breakers where the breakers are not allowed to be installed. Plain and simple that way, and the answer to 'which of those breakers are allowed to be where' will be on the label of the panel, which will show EXACTLY where those breakers may be installed, and, where not shown, they ARE NOT ALLOWED to be installed.

I specify pre-2008 NEC as the 2008 NEC allows for more than the old standard of 42 circuits, how many is determined by the listing and labeling on the panel. I have not seen any panels manufactured to the new 2008 NEC standard as yet, but the total number of breakers allowed will be specified on the label of the panel. Any special breakers will be addressed as to where those breakers would be allowed to be installed - again, that would all be specified and shown on the label of the panel.

The electrician in the letter sent me states " ... in my professional opinion this does not constitute a problem.", so let's see if the electrician's opinion is supported by code.

The 2005 NEC states: (underlining and bold are mine)
- 408.35 Number of Overcurrent Devices on One Panelboard.
- - Not more than 42 overcurrent devices (other than those provided for in the mains) of a lighting and appliance branch-circuit panelboard shall be installed in any one cabinet or cutout box.
- - A lighting and appliance branch-circuit panelboard shall be provided with physical means to prevent the installation of more overcurrent devices than that number for which the panelboard was designed, rated, and approved.
- - For the purposes of this article, a 2-pole circuit breaker shall be considered two overcurrent devices; a 3-pole circuit breaker shall be considered three overcurrent devices.

Then there is this:
- 110.3 Examination, Identification, Installation, and Use of Equipment.
- - (B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

As the above clearly shows, the NEC DOES NOT support the electrician's "professional" opinion, provided that is not one of the very new panels which is actually labeled for a different maximum number of circuits - to clarify this one potential exception, when was the panel installed, when were the breakers installed? If before 2008 the maximum number is 42.

45_breakers_in_42_circuit_panel_is_ok.pdf