Electrical Service-Panel

The electrical service panel would be considered the heart of the electrical system. A properly sized, correctly wired panel will serve the electrical needs of the home for many years. Proper care and inspection will reduce the potential of system level problems and failures.

 

electrical-service-panel1If you have many of today’s modern conveniences such as a dishwasher, clothes washer, dryer, electric heat and air-conditioning, your service is likely 100 Amps or greater. If your house has anything smaller than 100 Amps, upgrading  your service to 150 Amps or greater is highly recommended. If you have very few of the items mentioned, the inspection covered in this section may or may not reveal immediate problems associated with a small panel, but as you add more electrical devices, you will start to see issues that are discussed in this topic.

Look at the table below to help determine what level of electrical service panel you may have. Generally speaking, service panels are not well marked to provide you an exact rating number, but the fewer positions the lower the rating. More positions typically equates to larger service. This is all based on the assumption that the panel is supplied with large enough cables in the first place. If you live in an older house, don’t be surprised if you have add-on panels that are used to provide additional capacity, if they are installed correctly there should not be any problems. If you question the cable sizes, have an electrician look at the panel for greater clarity.

 

servicepanelchart-fullinit_

 

With our increased dependency on electricity, the minimum acceptable size of AC service panels has slowly increased over the years. If your house is in category A or B with the original AC service panel, upgrading to a 150 Amps or greater can be a wise decision, as adding additional circuits will be problematic. In fact, some insurance companies may not issue or renew a policy because of the fire risk associated with the smaller panels.

INSPECTING THE PANEL

With relative ease, and a tool or two, the homeowner can inspect the electrical service panel to identify conditions that may warrant further investigation or repair. Additionally, if you would like to analyze your AC requirements, send me an email and I can forward you an spreadsheet to calculate your AC demand. This will provide you a general reference of demand vs. capacity.

Visual Inspection: This level of inspection is performed with no more than the door open. No screwdrivers or tools should be required to expose the face of the panel. There should not be any exposed wires at this point. Your service panel should (generally) resemble this picture (for a panel newer than 1960). Look at the general condition of the panel.

  1. The door should open and close without difficulty or obstruction.
  2.  The panel should fit snug to the adjacent wall. No gaping holes around the panel face around the Sheetrock or wall covering. If you find conduit or Jacketed Metal Conduit (JMC) leaving the sides of the panel, this is okay assuming the electrical conductors are not exposed.
  3. With the door open, look for missing knockout where breakers may have been removed. TIP: Home centers have plastic filler plugs to cover these holes. 
  4.  No standing water, corrosion or signs of water in the panel is acceptable. Call an electrician for resolution.
  5. Look at all the breakers for deformation, if they look melted or are no longer holding their original shape, they should be replaced. This can also be an indication the breaker has or is exceeding its limitation.

Heat and your AC Service Panel: Heat generated by the electrical service panel is an indication of potential problems that may result in an interruption of service. Heat can be recognized in a couple of different ways. 1) by touch or, 2) or digital  infrared thermometer.  If you don’t own a digital thermometer, they can be purchased for a reasonable price ($15 to $100) over the Internet or discount tool supply. The digital thermometer will be referenced throughout HomeownerBOB and its a great addition to your tool box. You will find lots of uses for it.inferred-thermometer

Before you look for heat issues, try to answer these questions.

  1.  Have you noticed that you regularly trip breakers?
  2. Does it occur at a certain time of the day?
  3. Does it occur when you use specific appliances such as a vacuum cleaner or hair dryer?
  4. Is it the same breaker(s) that have to be regularly reset?

If you answer yes to any of these questions, it’s a good decision to replace the breaker(s) now. All breakers have a service life and can deteriorate over time due to frequent tripping or heavy loads. Large commercial breakers can be tested and repaired, but it is more economically feasible to replace residential breakers if there is any question of their reliability. Furthermore, this will further the isolation process of the breaker if it continues to trip.

  1. Test by Touch: Without a digital thermometer, you can place a finger on the face of the plastic breakers. TIP Look for temperature differential. If you find an individual breaker noticeably warm, and it has been tripping, you may have an issue, so have the breaker changed out. If you already changed it out and it is still warm, the load on the circuit is probably high. If the breaker has not been tripping, no further action is required. Just make a note in your inspection journal and look for a change from one inspection to the next.
  2. Test by Infrared Thermometer: TIP: Look for temperature differential. If you find 25% in temperature difference between the hottest breaker and the coolest, and it is not tripping, log it in your home inspection journal.
  3. Tripping Breakers: If the breaker has started tripping, replace it first, then try the following trick to resolve the issue if it continued to trip after replacement. TRICK: Identify everything plugged into this circuit and try moving some appliances to other circuits to de-load this one. If you can live with this change, you have solved the issue, no further action is required. If it’s not a convenient arrangement, you may need to hire an electrician to re-associate some outlets to different circuits. This can get expensive, but it will take an on-site analysis to figure it out. Regardless, re-associating the circuit should solve the problem.

Testing and Exercising Circuit Breakers:Some professionals recommend circuit breaker testing by switching breakers on/off 5 consecutive times once per year. HomeownerBOB considers this optional. If the service panel is over 10 years old and breakers were never exercised for test, cycling them may actually cause some deterioration. TIP: Determine the brand and style of the breakers and buy a couple of the most common sizes (15, 20’s and 30’s are the most popular) and keep them for an emergency. If you choose to exercise the circuit breakers in the future, you will have ready access to a replacements. If the house is fairly new, exercise them if you wish.

Service Panel and Breaker Caution:  If your service panel is a Federal Pacific brand, some municipalities require them to be replaced. FPE Panel Controversy.

gfci-breaker GFCI Circuit Breakers:These special breakers will look different than a standard breaker as it includes a test and reset button, just like a GFI (ground fault interruption)outlet. In newer houses the electrician may wire an entire bathroom or all the kitchen circuits as GFCI in lieu of installing individual GFI outlets. You may also use an outlet tester with a GFI  testing feature to trip the breaker. Either way will work but HomeownerBOB prefers to test at the outlet as this allows you to associate the outlets with the breaker. See Outlets and Switches.

afci-breakerAFCI Circuit Breakers:  AFCI  breakers may look like a GFCI, both will be properly labeled to identify the difference. Arc Fault Circuit Interruption breakers are designed to prevent fires based on an arc flash that could occur in an electrical appliance. Read their full description in US Gov. AFCI doc for more information. Since 2002, the NEC has required these breakers be used with all bedroom circuits. TIP: These breakers can be quite sensitive and may trip for no apparent reason. If your inspection finds no fault, the breaker has been replaced and it continues to trip, you may consider having an electrician evaluate the circuit. Even though HomeownerBOB cannot recommend the removal and replacement of this breaker with nothing other than the same breaker, there have been cases where replacement with a traditional standard breaker has solved the problem without issue. 

Replacing Breakers: There are many links on how to change out a circuit breaker. Here is just one. Replace a circuit breaker.  If you are replacing your own breakers, they should ALWAYS be replaced with a like-for-like size and rating of the breaker being removed. NEVER up-size a breaker because it continues to trip. If you replaced the breaker because it was hot and it is still hot or it continues to trip. Make a note in your inspection journal. If it starts to trip over the year, follow the testing isolation method described above. The NEC (National Electric Code) allows for residential grade breakers to supply up to 80% of their rating. So in other words, if you have a 20 Amp breaker, the actual measured load should not exceed 16 Amps (1920 Watts) at any one time.

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2 Responses to Electrical Service-Panel

  1. elinorloewen says:

    Interesting Read! Very detailed blog.
    Thanks for sharing

  2. […] you still have problems, review the tests found in the Electrical Service Panel post. Perform the tests that apply to the […]

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