A sub-panel is already installed on a second floor. It draws power from a 100 amp main panel downstairs. The sub-panel is feed by a 60 amp double pole breaker. The panel was installed for or by AC techs who were installing mini-split AC units. The sub-panel contains four breakers for the AC units and then one 15 amp and two 20 amp circuits were added to service general receptacles and lights on the second floor.

The house was recently bought and the new homeowners found very bad wiring such as no electrical boxes behind ceiling lights and fans, wiring duct taped together, a mixing of 12 and 14 AWG wire on the same circuit, and incidences like no neutral wire where outlets were installed.

In light of the many problems which we are knowledgeable enough to catch and understand, we would like to ask a question about the sub-panel to make sure the above description sounds on the surface like an okay set up. If so I take it that more circuits can be run from the sub-panel to add extra light and outlet receptacles in the living areas as needed. I take it that this is a proper use of the sub-panel to add circuits in addition to the AC it was put in to accommodate as long as there are slots on the panel. The homeowners are intending on upgrading the main panel to a 200 amp service soon. I take 200 amp to be the standard upgrade for homes. Are there any reasons that such an upgrade would be prohibited for local code reasons and concerns? They definitely need an upgrade since they are trying to properly wire the house to all new code requirements after the hurricane forced a gut of the whole first floor.

  • 1
    Your question is very confusing. You talk about some problems found with the wiring, a bit about a sub panel, and then you ask if you can upgrade the service. If you have multiple questions, it might make sense to post each question individually. If you're only concern is upgrading the main service, you may want to edit the question and omit some of the irrelevant details.
    – Tester101
    Commented May 28, 2013 at 16:22

3 Answers 3



Service upgrades tend to be expensive, since it usually involves installing a new service panel. Depending on your situation, you may find that the cost far outweighs the reward. If you already have 100 Amp service, and you haven't added on to the home, you may find the upgrade unnecessary.


The upgrade has to be supported by the existing infrastructure, otherwise the provider may charge you to upgrade their system. Just like the wires in your home have to be sized properly to carry the load, the distribution wires also have to be capable of providing the extra power. If the distribution system is at, or near its limit, the provider will have to make upgrades to the system before it can offer an upgrade to you. In this case the provider will either tell you it can't offer you the service, or they'll offer the service but only if you pay extra to help offset their costs. This is not a common scenario in most large US cities, though can still be encountered in less populated rural areas.

  • It's not that scary... upgrade the old 100A panel to a sub-panel fed from a new 200A panel, so you don't have to disturb the dozens of small circuits. Or have two main panels right next to each other - I've seen that in an all-electric house. Commented Sep 4, 2016 at 17:13

AC units PLUS additional circuits on the 60A sub-panel sounds like it's already overloaded. Frankly it sounds like a complete rewire is called for in addition to the 200A upgrade.

To answer your question, though - no, I'm not aware of any reasons NOT to go to 200A. Just be aware that utility companies will generally not do that upgrade w/o a properly completed inspection of the new panel work and anything tied to that replacement. But I trust you already intend to have the electrical work properly inspected, right? :)

  • My main concern about the subpanel is whether it is over loaded in the first place and whether they should have added anything to it beyond the AC units. I need to look up how to figure the capacity.
    – user11933
    Commented May 28, 2013 at 17:22
  • The house is gutted because of flood damage from the hurricane and the wiring needs to be redone. A new box has to be installed and if the kitchen, utility room, bathroom and living areas are to have up to code circuits I cannot see how a 100 amp service will be adequate. The old service has all kitchen appliances and counter outlets on one circuit and the box is basically full and then the subpanel upstairs has whatever capacity if any.
    – user11933
    Commented May 28, 2013 at 17:31

Just a late observation: Given the move to CFLs (and now LEDs), plus more energy-efficient devices and appliances, I'm not convinced that 200A service is still as much of a benefit as it once was... at least not unless you're charging an electric vehicle.

  • Heat pumps, on-demand water heaters. I've seen a house with two 225A main panels (northern clime, all-electric, heat pump w/ auxiliary heat). And he has an electric car and wants on-demand hot water, one for each end of the house. Commented Sep 4, 2016 at 17:21

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