Weatherhead

A weatherhead, also called a weathercap, service head or service entrance cap, is a weatherproof entry point for above-ground electrical wiring or telephone lines into a home or business. It is used at a service drop, where overhead wires from a utility pole supplying power or telephone service enter a building. At the building the wires enter a conduit, a protective metal pipe, and the weatherhead is a waterproof cap on the end of the conduit that allows the wires to enter without letting in water. It is shaped like a hood, with the surface where the wires enter facing down at an angle of at least 45°, to shield it from precipitation. A rubberized gasket makes for a tight seal against the wires. Before they enter the weatherhead, a drip loop is left in the overhead wires, which permits rain water that collects on the wires to drip off before reaching the weatherhead.

Weatherheads are required by most electrical codes and/or building codes. They are also used on utility poles where overhead power lines enter a conduit to pass underground.

What is a Weatherhead?

A weather head is a weatherproof electrical service point for your overhead electrical service feed. The weatherhead connects to the top of the electrical service pipe and has a cap over the connection frame. Since it sits atop the pipe, has a cap on top of it, and makes the connection weatherproof, it is called a weatherhead.

The weather head is connected to the pipe with a bracket, complete with two screws, that encompasses the pipe. The wires that feed the electric meter feed up through the pipe and come out of the weatherhead access holes. These holes are facing downward at an angle so that the rain cannot run into the holes. These wires are what the utility company connects their feeder wires to. There are different sized weatherheads, depending on the size of the electrical service and wire size.

How to Replace an Electrical Floor Outlet

Replacing an electrical floor outlet is not as hard as it may seem. Always follow local and national electrical codes while you work. Also be sure to read the manufacturer’s instructions carefully.

Tools and Materials

• Electric drill with hole saw if necessary
• Screwdriver
• Caulk

Step 1: Locate the Electrical Panel and Turn Power Off

The first thing you must do when working with anything electrical is to be sure the power is turned off. If you are replacing an existing outlet, turn off the power that supplies that outlet. Often the breakers are marked by the builder but sometimes they are incorrect. You may have to turn the breakers on and off, one by one, until you locate the correct one for your wire source. Always be sure to test with a circuit tester before beginning work.

Step 2: Remove the Outlet Box

You can remove the outlet box in the same way that it was installed. Remove any screws holding the plate cover onto the box and pull the unit out. If there was a bead of caulk placed between the outlet box and the subfloor, you may need to release this. You can use a flat screwdriver or a chisel and gently slide it under the lip and slowly pry it out. Do this gently so as not to damage your floor. Once the caulk is released, you can easily remove the outlet box.

Cut the wires and use wire nuts on the ends to cap them.

Step 4: Check Hole

If you have purchased the same unit as you are replacing, you will not need to adjust the floor hole size. If it is a different unit, be sure to check with the manufacturer’s instructions to be certain you have the correct hole size as well as the correct depth allowance.

Step 5: Connect the New Wires

If you have purchased the same unit as before, simply connect the wires in the same way you removed them. If you have purchased a different unit the color coding will remain the same: green to green, black to black, white to white.

Step 6: Install the Outlet

Push all the excess wires in the hole but clamp the romex, bent over, to the bottom of the box floor. Reinstall the bottom plate and clamp. The romex will exit into the bottom of the cover plate and is held by screws.

Place a bead of caulk on the floor around the outlet hole and place the assembled floor box into the hole, being sure it is well seated. Place the cover plate over the top and screw into the subfloor.

Step 7: Test the New Outlet

The final step is to test it to be sure it is operating properly.

3 Types of Electrical Conduit Weatherheads

There are many different types of electrical conduit weatherheads which are suitable for different purposes. The idea of electrical conduit weatherheads is to waterproof your system and to protect it from water damage. Understanding the different types of electrical conduit weatherheads should make it much easier to weatherproof your property and prevent any damage caused by rain water entering electrical conduits.

The right electrical conduit weatherhead is required to ensure that the electrical system in your home isn't exposed to the weather, specifically rain.

Other Names for Weatherheads

There are actually a number of different names for weatherheads all of which are basically the same thing. Weatherheads are also known as service entrance caps and weather caps, these are designed as a waterproof entry point to allow maintenance to wiring entering a building. These are used on both industrial and residential buildings and are used to drop cable down from the roof into the property. Weatherheads are important for use with electrical and telephone cables when they are coming from above.

The weather head itself is the watertight cap which seals the top of the conduit. This uses a rubberized seal to seal against the wires and to prevent water from getting inside. The wires overhead will also have a drip loop to prevent water tracking down the cable and into the conduit.

The angle of the cap is pointing down towards the ground. This is important because it helps to assist with the surface water runoff. Most building and electrical codes require the use of weather heads and they are also a common fixture on telephone and utility poles.

1. Different Sizes

There are various different sizes of weatherhead depending on the size of the electrical conduit being used to carry the wires down from your roof. It's important that the weather head is the correct size for the conduit to prevent water from getting inside. If it's too large or too small then this could potentially cause problems.

2. Telephone and Electrical

Telephone and electrical conduit weatherheads work in pretty much the same way. However, telephone conduits are often much smaller due to the smaller cable used.

3. Materials

Weatherheads are also available in a wide range of different materials. It's important to choose the right conduit for the job. This will normally be made from the same material as the conduit it is being fitted to. This will ensure a snug fit which will protect your home.

Getting Advice

If you're not sure about the type of weatherhead required then you can always ask in your local home hardware store for advice. These are normally installed as part of the utility companies installation which means that you shouldn't actually need to replace on yourself unless it has become damaged or broken.

Power in AC circuits:

Electricity is supplied as an alternating current (A.C.) for domestic and industrial use. The voltage of alternating current is not constant, as in the case of direct current current, (D.C.), and varies sinusoidally with time, at 50 cycles per second (in South Africa).

The alternating potential causes the current in the conductor to change in accordance with Ohm's law. Since the current varies continuously, how is it possible to calculate the heating effect? This can be done by defining effective values of the current, I, and the voltage, V.

"An alternating current is said to have an effective value of 1 ampere when it will develop the same amount of heat in a given resistance as would be produced by a direct current 1 ampere in the same resistance in the same time."

An effective value of the voltage can be defined in an analogous way.

If the effective values of the voltage and current are used, the power dissipation in an A.C. circuit may be calculated in the same way as for direct currents. The effective values are simply the root mean square values of the voltage and current.

In South Africa the effective value of the voltage is quoted as 220V.

Efficiency:

Domestic appliances convert electrical energy into other forms of energy. Appliances are generally marked with the recommended operating voltage and their total power consumption at that voltage.

In the case of appliances that produce light and motion, not all the electrical energy is converted into the desired form of energy, as some of the electrical energy is converted to heat. The fraction of energy converted to the desired form is the efficiency of the appliance, e, given by

Fuses:

When a curre nt is passed through a conductor, heat is generated, This is the principle which operates in FUSES. In order to protect equipment or appliances from large, unexpected currents, a fuse (one design is shown on the left) is placed in series in the circuit. It consists of a metal wire designed to melt, and hence break the circuit, o nce the current through it reaches a stated value.

Light bulbs:

An incandescent light bulb consists of an evacuated gla ss container, with conducting supports to hold a coil of fine tungsten wire. As the current passes through the filament, it reaches very high temperatures and emits energy in the form of light. Tungsten is chosen as the metal for the filament as i t has a high melting point (3410 ºC). The filament is in a vacuum in order to prevent oxidation of the metal, which would simply burn at the high operating temperature, if air were to be present in the bulb.

Since P = I²R, (the power dissipated in a light bulb is directly proportional to the square of the current flowing through it, and directly proportional to the resistance of the bulb), for a given current flowing through the bulb, the brightness of the light will increase as the resistance increases. On the other hand, for a given applied voltage, the brightness of the light will decrease as the resistance increases. Remember also that

• A good deal of the power is wasted in generating heat (more than 90%!)
• The resistance of the bulb will depend on the operating temperature and design of the filament.

The definition of emf (electromotive force)

In a circuit in which a current is present, the total rate at which energy is drawn from the source of current and dissipated in the circuit per unit current is defined as the electromotive force, (emf), in the circuit.

The emf is represented by the symbol E. From the above definition,

where P is the power dissipated in the circuit and I is the current flowing in the circuit.

The potential difference is defined as

"The potential difference between two points on a conductor is the work done per unit charge by a charge moving from a point of higher potential to that of lower potential."

Observe that potential difference is defined in terms of work and charge, whereas emf is defined in terms of power and current.

From the definition, we could define the unit of emf as the watt per ampere, which is the volt.

Both emf and potential difference have units of volts, as both are ultimately concerned with energy transformation per unit charge.

The emf of a battery:

The emf of a battery may be measured by connecting a voltmeter across its terminals. This measured potential difference is the same as the emf of the battery when it is not connected to a circuit.

In general, however, when the battery is connected to a circuit the potential difference measured by the voltmeter will be lower than the emf because of the internal resistance of the battery. Some of the energy dissipated in the circuit will be dissipated in this internal resistance.

The equivalent circuit is shown on the left, where r is the internal resistance of the battery with emf E, connected to a circuit with resistance R. The voltmeter measures the potential difference across R and not the emf of the battery which is equivalent to the potential difference across
(R + r).

Internal resistance:

Sources of electric currents, such as batteries or generators, are made of conductors. Since all conductors do have some resistance, batteries and generators will have a resistance of their own, called INTERNAL RESISTANCE, to distinguish it from the loads in a circuit, which are called EXTERNAL RESISTANCE. The internal resistance

comes into play when a current is flowing through the source, and results in a DECREASE in the measured potential difference across the source terminals. If one places a voltmeter across the terminals of a battery which is part of an open circuit, the voltage that is read is the electromotive force of the battery. How does one measure the internal resistance?

In a closed circuit, the voltmeter reading across the battery terminals is less than the battery emf. The difference is the voltage drop across the internal resistance r. If we know the current that is flowing through the circuit, let us say I, then

We see that the circuit voltage, V, is inversely proportional to the circuit current, I .

The heating effect of an electric current:

When a charge moves in a conductor, work is done by that charge. Devices can be made which convert this work into heat ( electric heaters), light (light bulbs and neon tubes), or motion, i.e. kinetic energy (power tools).

From the definition of potential difference, V, we have V = W/Q, where W is the work done by charge Q. Hence, W = VQ.

Current is the flow of charge, so that in time t, the amount of charge moving through the conductor will be Q = It.

Therefore, W = VIt gives the work done in time t, by a current I, flowing through a conductor across which the potential difference is V. This may be written in two other ways by substituting from Ohm's Law:

where R is the resistance of the conductor.

Electric power:

Remember that power is defined as the rate at which work is done:

By substituting from W = VIt, we obtain the formula for the power dissipated in an electric circuit, as follows:

This formula gives the power which is dissipated when a current I moves through a conductor across which there is a potential difference V.

From Ohm's law we may also write

The unit of power is the WATT, W which is equivalent to one joule per second, J.s^-1.