Building & Renovating

How To Know If Your House's Electrical System Is Safe

Though you can't see it, make sure to keep your home's electrical system in ideal condition

Original Article: Amillah Rodil Photography: Pixabay (Main Photo)

Electricity plays a big role in our lives, and yet we often take it for granted, because the system that carries it is hidden behind our walls and ceilings. When we renovate our home, we often focus on the aesthetics, such as the right paint colors and furniture.

But taking care of the basics—those things that are important, but cannot be seen—should always come first. These include the electrical system of the house.

Since we can’t see what’s wrong with the system, we normally assume that it’s okay. However, it is also possible that our electrical systems may have wires that are only steps away from a short circuit or an overload, which could be a big danger to our homes and families.

That is why it is important to get the advice of professionals, because they know what to look out for. We consulted professional electrical engineer Cesar S. Bravo, who has had more than ten years’ worth of experience in working with building electrical systems. Here, he answers questions about giving your electrical system a check-up.

What happens to an electrical system over time?

It depends on how you use it. Abuse and misuse of your electrical system, such as “octopus” connections and overloading, can decrease the ampacity (ability to carry current without overheating) of the wires. If you don’t overload an electrical system, your wires can last 50 years or more.

Temperature can also influence their condition. Wires deteriorate faster in high temperatures, so wires age faster here in the Philippines than in colder countries.

When should I consult a pro?

Don’t wait until something happens. Ideally, you should have your electrical system checked every year. Aside from a yearly check-up, consult an electrical engineer when 1) you’re planning to buy an old house and you need to assess its condition; 2) you’re planning a renovation or extension of your house; 3) you want to add more lights, outlets, or appliances; and 4) you’re experiencing problems, such as tripping of circuit breakers, which is a sign of overloading.


Whom should I consult?

It is best to get advice from a licensed Professional Electrical Engineer (PEE) with experience in design, supervision, and installation of building wiring and electrical systems. An architect or a designer may be able to refer you to one.

A Master Electrician and a Registered Electrical Engineer (REE) are also licensed to deal with electrical systems. A Master Electrician can do installation, maintenance, and repair, while an REE can do electrical design and supervise installation. However, the PEE has the sole authority to sign and seal electrical plans.

How do you know if an electrical system is healthy?

First, the engineer will do a visual inspection, which involves checking for damage, such as if the wires have turned brittle or if the insulation or protective coating has carbonized. Carbonization occurs when there is overheating or overloading. You’ll know if the wire has carbonized when the insulation or protective coating turns white. This is dangerous because if the wire is carbonized, it becomes a conductor, which means that if it comes into contact with another wire, a short circuit can occur and cause a fire.

Are tests necessary?

Aside from the visual inspection, electrical engineers conduct two basic tests to check if your house needs rewiring: The load test and the insulation resistance test. The load test checks if the wires can carry current without overheating, and whether the supply voltage is within the normal operating range. The insulation resistance test checks the condition of the wires. If the test results fall below the standard, the wires will need to be replaced.

Is the age of the house a factor?

Though tests will reveal the real condition of the system, the age of the house is also one consideration in rewiring. The older your house is, the less reliable your electrical system will be. Your electrical system may need rewiring if it has these fixtures: 1) solid wires (new ones are composed of strands); 2) wooden conduits (new ones are composed of PVC); 3) open wiring without conduits; and 4) a dilapidated or rusty safety switch.


What are the corrective measures that an electrical engineer can propose?

The objective of giving your electrical system a check-up is to see that it conforms to the standards of the Philippine Electrical Code (PEC). After inspection, the electrical engineer will submit to you a technical report detailing the condition of the system and the recommended corrective measures. One of these may be the installation of a grounding system, since many houses here in the Philippines don’t have one. A grounding system protects appliances, properties, and people, especially when lightning strikes or when a surge occurs in an electrical circuit. Recommendations can also include the splitting up of certain circuits to lessen the load on the circuit. Or, it can be as simple as tightening the bolts on your panel board.

The electrical engineer may also propose rewiring, or the replacement of the wires in your system. Rewiring can be limited to a few circuits only, or it can cover the whole system. Aside from these, the engineer may also recommend the replacement of devices such as the circuit breakers, the panel board, and the service entrance. When the work includes the replacement of these devices, it is called upgrading. If your electrical bill is running high, an electrical engineer can also give you tips on how to conserve energy.

What does upgrading of the electrical system entail?

During rewiring, the electrical contractor will shut down the circuits he’s working on, so some of your daily tasks may be interrupted depending on what area of the house the circuit goes through. Since they’ll be replacing the wires, the contractor needs access to the ceiling, where wires usually go through. If there is no manhole in the ceiling, the workers might have to create one themselves. Chipping of walls may be necessary if the location of power outlets and switches needs to be changed, or if outlets need to be added. Tests and inspections may last for a day or two, while upgrading may last for a week.


If the service entrance needs upgrading, you need to get an electric permit before any kind of work is started. This needs to be signed and sealed by the PEE and submitted to your local building official. After installation of the new service entrance, the utility company (e.g., MERALCO), requires a Certificate of Final Electrical Inspection (CFEI) before the service entrance can be energized. The electrical engineering department of the local building official will issue the required CFEI only if they find that the wiring installation conforms to the standards of the PEC.

Who can do the rewiring/upgrading?

Electrical contractors can do the rewiring for you. Otherwise, the professional electrical engineer you consulted may have his or her own people who can do the job. It is usually better if the engineer who made the inspection supervises the upgrading, because he or she is already familiar with the system.

How much will it cost?

An inspection by a PEE can cost about Php1,500 per visit. If it includes the basic tests like the load test and the insulation resistance test, it can cost about Php6,000. The rewiring for a three-bedroom house can cost about Php35,000. If the services include upgrading the devices, it can cost around Php50,000, including labor and materials. Sometimes, people don’t want to spend this much if they don’t see anything wrong with the system, but this is just like insurance: You don’t want to wait for something bad to happen, because if your house ends up burning down, you’ll end up losing more.

This article originally appeared as “Are You Wired Well?” in the March 2006 issue of Real Living magazine.

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