# Short-Questions

Fast solutions for complex problems

24

## How often do wires need to be secured?

General Cable Support Runs of NM cable must be supported at least every 54 inches. They also must be secured within 12 inches of an electrical box that includes a cable clamp or within eight inches of a box or enclosure without a cable clamp.

### What are electrical drops?

An electric service drop is the bundle of electrical cables that run from the electric utility company’s power pole to the connection at your house. Because the power company lines are higher than your home, the cables that go to your home literally drop, descending from a higher spot to a lower spot.

How long should wiring last?

The Life Expectancy of Wiring As a general rule, home wiring can last past 50 years. But it can also be far less than this—for example, if the wiring was badly installed in the first place or amateur modifications were made to it at some point.

When should you consider voltage drop?

4) in the National Electrical Code states that a voltage drop of 5% at the furthest receptacle in a branch wiring circuit is acceptable for normal efficiency. In a 120 volt 15 ampere circuit, this means that there should be no more than a 6 volt drop (114 volts) at the furthest outlet when the circuit is fully loaded.

## Can you run electrical wire behind studs?

Yes, you can run the cable behind the studs. In these situations, you often see the electrician only drill a hole in every other stud and run behind the stud between. You can also afford to offset the drilled holes towards the back of the stud to get them even farther from possible damage from nails.

### How many wires can you run through a hole?

According to the National Electrical Code, you can have 4 12/2 nonmetallic sheathed cables through a single bored hole that is fire- or draft-stopped using thermal insulation, caulk, or sealing foam, or where proper spacing is not maintained for more that 24 in.

Can I touch the power line going to my house?

Power lines are not insulated and you should always avoid contact with them. It is quite possible for people to get electrocuted if you touch power lines.

What are the three wires coming into my house?

The answer becomes clearer when we look at the three roles wiring must fulfill: hot, neutral, and ground. These three components work in tandem to distribute power throughout your home, as well as help maintain electrical safety.

## At what age should a house be rewired?

If a property is more than 30 years old and has the original wiring, it is likely to need updating, at least in part, to meet modern standards, including replacing the fuse box with a modern consumer unit. A sign a rewire is necessary, is dated rubber, fabric or lead-insulated cabling.

### Does a 1970s house need rewiring?

Most of the 1970s houses have no need for rewiring. They will probably need a consumer unit and upgrade. The electrician will inspect a lot of the property if you have a consumer unit change.

What is the max voltage drop allowed?

The NEC recommends that the maximum combined voltage drop for both the feeder and branch circuit shouldn’t exceed 5%, and the maximum on the feeder or branch circuit shouldn’t exceed 3% (Fig. 1). This recommendation is a performance issue, not a safety issue.

What happens in a voltage drop?

Voltage drop is defined as the amount of voltage loss that occurs through all or part of a circuit due to impedance. Excessive voltage drop in a circuit can cause lights to flicker or burn dimly, heaters to heat poorly, and motors to run hotter than normal and burn out.

## When do shorter wires have less voltage drop?

Shorter wires will have less voltage drop than longer wires for the same wire size (diameter). Voltage drop becomes important when the length of a run of wire or cable becomes very long. Usually this is not a problem in circuits within a house, but may become an issue when running wire to an outbuilding, well pump, etc.

### How is the voltage drop of a wire calculated?

Voltage drop is calculated using the most universal of all electrical laws: Ohm’s Law. This states that the voltage potential across the conductor is equal to the current flowing through the conductor multiplied by the total resistance of the conductor. In other words, Vd = I x R.

What happens when an electric service drop goes down?

All electricity to your home comes through the service drop. If the service drop goes down, all power in your home will shut off. Catastrophic events, such as downed trees, large fallen limbs, or heavy ice buildup, can take down a service drop.

How much voltage drop does a feeder circuit need?

The National Electrical Code states that the voltage drop of a feeder circuit must not exceed 5%, and the voltage drop of a branch circuit must not exceed 3%.