I followed up on a home inspection report today and opened up a residential 150 Amp 30 ckt panel which contained mostly mini breakers for a total of 34 branch circuits with about 8 full size spaces still open. It was not a "CTL" panel. The home inspection report noted that there was "additional capacity available". The bus diagram on the door only depicted full size breakers (one per space = 30).
You might check on the label for the "approved" C/Bs to be used with the loadcenter to see if it allows for the use of the minis (AKA junks). If not, it's subpanel time. ???Is a CTL required where the available fault current is low (<10KA)? (I don't know the answer to this one)
Re: Non-CTL panel#6266 12/28/0108:56 AM12/28/0108:56 AM
I'm mainly just curious about the use of mini breakers in a non-CTL panel and how many breakers can properly be installed. I'm thinking only 30 full size(no minis). Someone could conceivably install 60 mini breakers in this panel. The reason that I was called in was because the home inspector "recommended the service be upgraded to 200 amp". What his recommendation is based on, I haven't a clue. He didn't say. Now the buyers want a 200 amp upgrade. This was immediately after his remark that "there was additional capadity available". This, I assume was due to the 8 available spaces. I did a calculation for existing dwellings and determined that about 115 amps is adequate for this size home.
Re: Non-CTL panel#6269 12/29/0105:39 AM12/29/0105:39 AM
I never heard of an Inspector requiring a service upgrade without having calculations from NEC Article 220 that would justify such. Calculations from Article 220 would clearly indicate if one was needed.
Sparky: Class CTL means "circuit limiting" See Section 384-15, paragraph 2 in the 1999 NEC:
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.
From the UL White Book: "Class CTL panelboards are identified by the words "Class CTL" on the Underwriters Laboratories Inc. Follow-Up Service Listing Mark.
Class CTL panelboards incorporate physical features which in conjunction with the physical size, configuration, or other means provided in Class CTL circuit breakers, fuse holders, or fusible switches, are designed to prevent the installation of more overcurrent protective poles than that number for which the device is designed and rated."
I have images showing this information on the equipment.
He's not a real electrical inspector. He's one of the "Home Inspection Service" employees. This is a popular concept in recent years in which a home buyer will pay about $300.00 to have someone give a home that they want to buy the once-over. It is just a cursory inspection of the major parts of the home. Often, they recommend a professional tradesman evaluate certain systems furhter. As I said, his "recommended upgrade" seems to be just a thought on his part because he didn't have any basis for it. Problem is, now the buyers are requesting the upgrade. The "existing dwelling" calculation falls well within the existing 150 amp service, so I can honestly say it doesn't need an upgrade. I don't like all these mini breakers in this panel. (He didn't seem to mind them). However, I was called to asses the service capacity only, not the inside of the panel. It's an awkward situation, I wish I hadn't seen the panel.