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Why You Should Avoid Overcrowding Holes with Too Many Wires

Mon, 20 Mar 2023 22:20:51 GMT

Disclaimer: The following instructions are intended for licensed electricians who have the necessary skills and experience to perform electrical work safely and correctly. This guide is only meant to refresh your memory and does not cover all the details or variations that may apply to your specific situation. This guide is not a substitute for proper training and certification, but rather a refresher of the basic steps and precautions involved in installing or repairing electrical systems. You must always follow the national and local electrical codes and regulations that govern your area. Failure to do so may result in serious injury, property damage, or legal consequences.

Why You Should Avoid Overcrowding Holes with Too Many Wires

One of the common wiring mistakes that homeowners and DIYers make is overcrowding holes with too many wires. This can create several problems that can compromise the safety and performance of your electrical system.

What is overcrowding?

Overcrowding occurs when you run more wires than allowed through a hole in a stud, joist, or other framing member. The National Electrical Code (NEC) specifies the maximum number of wires that can be installed in a hole based on the size and type of the wire and the diameter of the hole. For example, according to NEC Table 300.4(E), you can run up to nine 14-gauge NM-B cables (nonmetallic sheathed cable) through a 7/8-in. hole, but only four 12-gauge NM-B cables through the same hole.

Why is overcrowding bad?

Overcrowding holes with too many wires can cause several issues, such as:

Heat buildup: When current flows through a wire, it generates heat. If too many wires are bundled together in a tight space, they may not dissipate heat properly and cause overheating. This can damage the insulation of the wires and create a fire hazard.
Wire damage: When you drill holes for wires, you must maintain at least 1 1/4-in. clearance from the edge of the framing member to protect the wires from nails or screws that may puncture them during drywall or trim installation. If you overcrowd a hole with too many wires, you may reduce this clearance and expose them to potential damage.
Wire stress: When you pull wires through holes, you must avoid damaging them by bending them too sharply or applying excessive force. If you overcrowd a hole with too many wires, you may create more friction and tension on the wires and cause them to stretch or break.
Code violation: Overcrowding holes with too many wires is against the NEC and may result in failing an electrical inspection or getting fined by your local building authority.

How to avoid overcrowding?

To avoid overcrowding holes with too many wires, you should follow these tips:

Plan ahead : Before drilling any holes for wires, plan your wiring layout carefully and determine how many wires you need to run through each hole. Use NEC tables or online calculators to check how many wires are allowed for each hole size and wire type.
Use larger holes : If possible, use larger drill bits to make bigger holes for your wires. This will allow more space for heat dissipation and wire protection. However, do not exceed 40% of the cross-sectional area of a wood framing member when drilling holes.
Use fewer tandem breakers : One of the main reasons for overcrowding panels with too many wires is using tandem breakers (also called duplex or half-high breakers) that fit two circuits into one slot. These breakers are only allowed in certain panels and locations according to manufacturer specifications. Using too many tandem breakers can create an overpacked panel that makes it hard to follow or trace individual circuits.
Use subpanels : If your main panel does not have enough space for all your circuits, consider installing a subpanel instead of cramming more wires into existing holes. A subpanel is an additional panel that connects to your main panel via a feeder circuit. It provides more slots for breakers and allows more flexibility for wiring distribution.

Overcrowding holes with too many wires is a common wiring mistake that can lead to serious consequences if left unchecked. By following these tips above.

If you have any questions about wiring installation or need professional help with your electrical project, contact us today at 818-265-9944 or info@downtownelectricsupply.com . We have licensed electricians on our team who can provide quality service.

This Is How You Can Prevent Electrical Shocks

Mon, 20 Mar 2023 21:44:55 GMT

Insufficient Electrical Bonding: Why You Should Follow the NEC Guidelines

Electrical bonding is a process of connecting metal parts of an electrical system to establish electrical continuity and conductivity. Bonding ensures that all metal parts are at the same potential and provides a low-impedance path for fault currents to flow back to the source. Bonding also reduces the risk of electric shock and fire by preventing voltage differences between metal parts that could cause arcing or sparking. The National Electrical Code (NEC) is a set of standards that regulate the safe installation of electrical wiring and equipment in buildings and structures. The NEC contains specific requirements for grounding and bonding of electrical systems, which are intended to protect people and property from hazards arising from the use of electricity.

Grounding is a process of connecting an electrical system or equipment to earth, or to a conductive body that extends the earth connection. Grounding provides a reference point for the voltage of an electrical system and helps stabilize it against fluctuations. Grounding also facilitates the operation of overcurrent devices, such as circuit breakers and fuses, by providing a path for fault currents to flow. The NEC requires different types of grounding and bonding for different types of electrical systems and equipment. For grounded systems, which have one conductor intentionally connected to earth, such as most residential and commercial systems, the NEC requires:

Electrical system grounding: This involves connecting the grounded conductor (usually neutral) of an electrical system to a grounding electrode system (GES), which consists of one or more conductive objects buried in or near the earth, such as ground rods, metal water pipes, concrete-encased electrodes, etc. The GES provides a direct connection between the electrical system and earth.
Electrical equipment grounding: This involves connecting non-current-carrying metal parts of electrical equipment, such as enclosures, raceways, conduits, cabinets, etc., to an effective ground-fault current path (EGFCP), which is a low-impedance path that can safely carry fault currents back to the source. The EGFCP usually consists of equipment grounding conductors (EGCs), which are wires run along with circuit conductors that connect equipment grounds to system grounds.
Electrical equipment bonding: This involves connecting exposed non-current-carrying metal parts that are likely to become energized due to contact with live parts or induced voltages, such as metal frames, pipes, ducts,
ladders, etc., to an EGFCP. This prevents these metal parts from becoming hazardous by limiting their voltage difference with respect to other grounded parts.
Bonding of electrically conductive materials: This involves connecting electrically conductive materials that are not part of an electrical circuit but may be located near one, such as gas piping systems, structural steel members, metal fences, etc., to an EGFCP. This prevents these materials from becoming sources of ignition or shock by eliminating potential differences between them and other grounded parts.

For ungrounded systems, which have no intentional connection to earth, such as some industrial and health care systems, the NEC requires the same types of grounding and bonding except for electrical system grounding.

Insufficient electrical bonding can result in serious consequences,

such as:

Electric shock: If a person touches two metal parts that have different potentials due to insufficient bonding, they may receive a harmful electric shock. This can cause injury or death depending on the severity of the shock.
Fire: If insufficient bonding causes arcing or sparking between metal parts, it may ignite flammable materials nearby, such as gas vapors, wooden structures, or insulation materials. This can cause fire damage or explosion hazards.
Equipment damage: If insufficient bonding causes excessive fault currents to flow through equipment components that are not designed to handle them, it may damage or destroy them. This can cause malfunctioning or failure of critical devices, such as motors, transformers or control panels.

To avoid these risks, it is essential to follow the NEC guidelines for electrical bonding when installing or maintaining electrical systems and equipment. The NEC provides detailed rules on how to select appropriate bonding methods and materials based on various factors, such as:

Type and size of electrical system and equipment;
Location and environment;
Available grounding electrodes;
Fault current levels;
Load characteristics;
Special conditions; etc.

The NEC also specifies minimum requirements for testing and verifying the effectiveness of bonding connections, such as:

Resistance measurements;
Continuity tests;
Visual inspections; etc.

By following the NEC guidelines for electrical bonding, you can ensure that your electrical installations will prevent most shocks and fires.

Why You Should Always Use a Cable Clamps

Mon, 20 Mar 2023 21:31:21 GMT

Installing Cable With or Without a Clamp

A cable clamp is a device that attaches the cable to the box and prevents it from being pulled out or damaged by friction. Cable clamps come in different types and sizes depending on the type of box and cable you are using. Some boxes have built-in clamps that you can simply tighten with a screwdriver. Others require you to install a separate clamp that fits into a knockout hole in the box. Cable clamps are required by the National Electrical Code (NEC) for safety reasons and to ensure proper electrical connections.

Why Use a Cable Clamp?

A cable clamp provides several benefits when installing electrical cables:

It protects the cable from abrasion, cuts, or nicks that could expose the conductors and create a fire hazard or a shock hazard.
It prevents strain on the cable and its connections, which could cause loose wires, arcing, overheating, or short circuits.
It prevents accidental disconnection of the cable from the box, which could leave live wires exposed or damage other components in the circuit.
It helps maintain proper grounding of metal boxes and conduit bodies by ensuring good contact between the cable armor and the box.

When Do You Need a Cable Clamp?

The NEC requires that you use a cable clamp whenever you install a cable into a metal box or conduit body [Sec. 314.17 (C)]. This applies to all types of cables, such as nonmetallic sheathed cable (NM), armored cable (AC), metal-clad cable (MC), mineral-insulated metal-sheathed cable (MI), etc. The NEC also requires that you use a cable clamp whenever you install NM cable into any type of box that does not have integral clamps [Sec. 334.30]. This means that if you use plastic boxes without built-in clamps, you must use an external clamp to secure the NM cable to the box.

There are some exceptions to these rules:

You do not need a cable clamp if you install NM cable into plastic boxes with integral clamps [Sec. 314.17 (C) Exception No. 1].
You do not need a cable clamp if you install MI or MC cables into listed fittings that provide adequate strain relief [Sec. 314.17 (C) Exception No. 2].
You do not need a cable clamp if you install flexible cord into boxes with fittings designed for this purpose [Sec. 400.14].

How Do You Install a Cable Clamp?

There are different types of cable clamps available for different applications and situations. Some common types are:

Screw-in clamps: These are metal devices that screw into knockout holes in metal boxes and have one or two screws that tighten around the cables entering through them.
Snap-in clamps: These are plastic devices that snap into knockout holes in plastic boxes and have spring-loaded tabs that grip around the cables entering through them.
Squeeze clamps: These are metal devices that fit around knockout holes in metal boxes and have two halves that squeeze together around the cables entering through them.
Locknut-and-bushing clamps: These are two-piece devices that consist of a locknut that screws onto threads on an opening in a metal box and a bushing that fits over the locknut and has one or more openings for cables entering through it.

To install any type of clamp, follow these steps:

Turn off power to the circuit at the main panel and verify it is off using a voltage tester.
Remove an appropriate knockout hole from the box using pliers or a screwdriver.
Insert one end of each cable through an opening in the clamp so there is at least 1/4 inch of sheathing inside the box [Sec. 314.17 (B)].
Attach the clamp to the box according to its instructions, making sure it is tight and secure.
Strip off enough insulation from each conductor so they can be connected properly inside the box [Secs. 110.14 (B), 300.14].
Connect the conductors according to their intended function, using wire nuts, screw terminals, or other approved means [Secs. 110.14 (A), 300.5].
Fold the excess length of conductors neatly inside the box so they do not interfere with each other or with devices installed in the box [Secs. 300.11(A), 3126(A)].
Install devices such as switches, receptacles, or luminaires according to their instructions, making sure they fit snugly against the wall surface [Secs.,11012(B), 40610(B)].

This Is How You Can Find the Correct Box Size

Mon, 20 Mar 2023 21:01:32 GMT

If you are planning to do some electrical wiring in someone's home or office, you may wonder what kind of electrical box you need to use. Electrical boxes are metal or plastic enclosures that house wires, switches, outlets, and other devices. They protect the wires from damage and provide a secure connection point for the devices.

But not all electrical boxes are created equal. Depending on the number and size of wires you are working with, you need to choose an electrical box that has enough space to accommodate them safely and comply with the National Electrical Code (NEC). Here we will explain how to determine the correct size of electrical box for your wiring project using some simple guidelines and calculations.

Why Box Sizing Matters

Box sizing is important for several reasons:

It prevents overheating of wires and devices. If an electrical box is too small for the number of wires it contains, it can cause excessive heat buildup inside the box. This can damage the insulation of the wires and create a fire hazard.
It prevents short circuits and arcing. If an electrical box is too small for the number of wires it contains, it can cause them to bend sharply or touch each other. This can create a short circuit or an arc fault, which can result in sparks, shocks, or fires.
It ensures proper grounding and bonding. If an electrical box is too small for the number of wires it contains, it can interfere with the grounding and bonding connections of the wires and devices. This can compromise their safety and performance.
It complies with code requirements. The NEC sets minimum standards for box sizing based on various factors such as wire size, wire type, device type, conduit type, etc. Failing to meet these standards can result in code violations, fines, or penalties.

How to Choose the Right Box for Your Wiring Project

One of the most important aspects of any wiring project is choosing the right box for your wires. The box is where you connect and protect your wires from damage and fire hazards. If you use a box that is too small or too large for your wires, you may run into problems such as overheating, short circuits, loose connections, or code violations. The National Electrical Code (NEC) provides guidelines for box sizing based on the number and size of wires you're working with. The NEC specifies the minimum volume of the box in cubic inches (cu. in.) that you need to accommodate your wires. To find out the required volume of your box, you need to follow these steps:

Identify the type and size of your wires. Different types of wires have different capacities and thicknesses. For example, a 14-gauge copper wire can carry up to 15 amps of current and has a diameter of about 0.064 inches, while a 12-gauge copper wire can carry up to 20 amps and has a diameter of about 0.081 inches.
Count the number of wires that will enter the box. You need to count each wire that passes through or terminates in the box as one wire. You also need to count any devices that will be installed in the box, such as switches or receptacles, as two wires each.
Add any allowances for clamps or fittings that will be used in the box. Some boxes have built-in clamps or fittings that secure the wires to the box. These clamps or fittings take up some space in the box and need to be accounted for in your calculation. The NEC provides specific allowances for different types of clamps or fittings depending on their size and shape.
Multiply the number of wires by their volume factor according to their size and type. The NEC provides a table that shows how much volume each wire occupies in cubic inches based on its gauge and material (copper or aluminum). For example, a 14-gauge copper wire has a volume factor of 2 cu.in., while a 12-gauge copper wire has a volume factor of 2.25 cu.in.
Add up all the volumes from steps 2, 3, and 4 to get the total required volume for your box.
Compare your total required volume with the actual volume of your box. You can find out the actual volume of your box by checking its label or measuring its dimensions (length x width x depth). Your actual volume must be equal to or greater than your required volume; otherwise, you need to use a larger box.

Here is an example:

Suppose you want to install a single-pole switch in a plastic octagonal ceiling box with four 14-gauge copper wires entering it: two hot wires (black), one neutral wire (white), and one ground wire (green). How do you determine if this box is big enough for your wiring project?

First, you count how many wires will enter the box: four individual wires plus one device (the switch) equals five wires.

Second, you add any allowances for clamps or fittings: since this plastic octagonal ceiling box has no built-in clamps or fittings, there are no allowances needed.

Third, you multiply each wire by its volume factor: four 14-gauge copper wires have a total volume factor of 8 cu.in., while one device has a total volume factor of 4 cu.in.

Fourth, you add up all the volumes: 8 + 4 = 12 cu.in.

Fifth, you compare this total with the actual volume of your box: according to its label, this plastic octagonal ceiling box has an actual volume of 15 cu.in., which is more than enough for your wiring project.

Therefore, this plastic octagonal ceiling box is suitable for installing a single-pole switch with four

14-gauge copper wires.

Choosing the right size box for your wiring project is essential for safety and efficiency reasons.

By following these simple steps based on NEC guidelines, you can ensure that your wiring project meets code requirements and avoids potential hazards.

How to Size Electrical Boxes by Volume

The volume of an electrical box is measured in cubic inches (cu.in.). It represents how much space is available inside the box for wires and devices. To determine if an electrical box has enough volume for your wiring project, you need to calculate how much volume each wire and device takes up inside the box. The NEC provides a table (Table 314.16(A)) that lists how much volume each wire size requires based on its type (solid or stranded) and insulation (THHN/THWN-2/T90). For example:

A 14 AWG solid THHN/THWN-2/T90 wire requires 2 cu.in. per wire
A 12 AWG stranded THHN/THWN-2/T90 wire requires 2.25 cu.in. per wire
A 10 AWG solid THHN/THWN-2/T90 wire requires 2.5 cu.in. per wire
A 8 AWG stranded THHN/THWN-2/T90 wire requires 3 cu.in. per wire

You also need to add extra volume for other components inside the box such as:

Grounding wires: add one volume allowance based on the largest grounding wire size entering the box
Cable clamps: add one volume allowance based on each cable clamp used inside or outside of metal boxes
Devices: add two volume allowances based on each device (switch or outlet) installed in metal boxes; add one volume allowance based on each device installed in nonmetallic boxes
Hickeys: add one volume allowance based on each hickey used inside metal boxes

Once you have calculated how much volume each component takes up inside your electrical box,

you need to compare it with the actual volume of your chosen electrical box.

The NEC provides another table (Table 314.16(B)) that lists how much volume various types and sizes of standard metal boxes have.

For example:

| Type | Size | Volume |

| Square | 4 x 1¼ inches | 21 cu.in |

| Square | 4 x 1½ inches | 25 cu.in |

| Square | 4 x 2⅛ inches | 30½ cu.in |

| Octagon | 4 x1¼ inches |18 cu.in |

| Octagon |4 x1½ inches |21½ cu.in |

You can also find nonstandard metal boxes and nonmetallic boxes with different volumes.

Follow These Steps to Install Electrical Panels

Mon, 20 Mar 2023 17:37:34 GMT

How to Install Electrical Panels

Electrical panels are the main distribution point for the electrical circuits in your home. They contain circuit breakers that protect each circuit from overloading or short-circuiting. Installing an electrical panel is not a simple DIY project and requires careful planning, preparation and safety precautions. Here are some steps to guide you through the process of installing an electrical panel.

Step 1: Select the right panel for the job

Electrical panels are available in different sizes and configurations. You need to select the right panel based on the electrical load requirements of your home or building.

Step 2: Choose the right location for your panel

The location of your panel should be easily accessible, well-ventilated and dry. It should also be away from any sources of heat, moisture or flammable materials. The panel should be mounted on a sturdy wall with enough space around it for wiring and servicing. You should also check with your local building codes and utility company for any specific requirements or restrictions on where you can install your panel.

Step 3: Install the feeder pipe

The feeder pipe is a metal conduit that connects the service entrance cable from the utility meter to the panel. You will need to measure and cut the pipe to fit your location and secure it with straps or clamps every few feet along its length. You will also need to install a connector into each end of the pipe that will attach to the meter box and the panel.

Step 4: Install a surge protector

A surge protector is a device that protects your electrical system from power surges caused by lightning strikes, faulty wiring or other sources. A surge protector can be installed inside or outside your panel depending on its type and design. To install a surge protector, you will need to follow its manufacturer's instructions carefully and connect it to the appropriate terminals on your panel.

Step 5: Install the panel

To install the panel, you will need to level it using a spirit level and mark its position on the wall with a pencil. Then you will need to drill holes in the wall according to its mounting holes and insert screws or bolts through them into wall anchors or studs. Next, you will need to pull the feeder wires through the pipe using a fish tape or wire puller and leave enough wire so it can easily connect to the opposite side of the panel.

Step 6: Connect the wires

To connect the wires, you will need to strip about half an inch of insulation from each wire using wire strippers and bend them into hooks using needle-nose pliers. Then you will need to loosen the screws over each terminal on your panel and insert each wire into its corresponding terminal according to its color code:

The black hot wire goes into one of two hot bus bars at either side of your panel.
The white neutral wire goes into one of several neutral bus bars at either side or center of your panel.
The bare copper ground wire goes into one of several ground bus bars at either side or center of your panel.

After inserting each wire, tighten its screw until snug but not too tight.

Step 7: Install circuit breakers

Circuit breakers are devices that interrupt power flow when a circuit exceeds its rated current capacity or experiences a short circuit. To install circuit breakers, you will need to snap them into place on their designated slots on your panel's hot bus bars according to their amperage rating and type (single-pole, double-pole, etc.). Then you will need to connect their load wires (the wires that go out from your panel) using similar steps as above:

Strip about half an inch of insulation from each load wire using wire strippers.
Bend them into hooks using needle-nose pliers.
Loosen their terminal screws on their circuit breakers.
Insert each load wire into its corresponding terminal according to its color code (black for hot, white for neutral).
Tighten their terminal screws until snug but not too tight.

Step 8: Label circuits

Labeling circuits is important for identifying which breaker controls which outlet, switch or appliance in your home. To label circuits, you can use stickers, markers or tags provided by your breaker manufacturer or create your own labels using paper and tape. You should write down clearly what each circuit powers (e.g., kitchen lights) and stick it next to its corresponding breaker on your panel's door.

Step 9: Test circuits

Testing circuits is essential for ensuring that everything works properly and safely after installation. To test circuits, you will need to turn on all switches, outlets and appliances connected to each circuit one by one while checking if they receive power correctly without tripping any breakers

Please note that this is for informational purposes only and not intended as professional advice. You should always consult a licensed electrician before attempting any electrical work.

10 Common Mistakes Every Electrician Should Avoid

Mon, 20 Mar 2023 17:37:34 GMT

Here are 10 mistakes you should avoid as an electrician.

Projects without a permit

Always check with your local building department to see if a permit is required for your project. If it is, make sure to obtain one before starting the work.

One of the most important steps in planning any construction or renovation project is to check with your local building department if a permit is required. A permit is a legal document that authorizes you to perform certain work on your property, such as adding a room, installing a fence, or replacing a roof. A permit ensures that your project meets the minimum standards of safety, health, and environmental protection set by your municipality. It also allows the building department to inspect your work and verify that it complies with the codes and regulations. If you fail to obtain a permit for a project that requires one, you may face serious consequences such as fines, penalties, delays, or even demolition of your work. Therefore, it is always advisable to contact your local building department before starting any work on your property and follow their instructions on how to apply for and obtain a permit.

Grounding methods

Make sure to follow the National Electrical Code (NEC) guidelines for grounding methods. If you're unsure about the proper grounding method, consult with a licensed electrician.

Grounding methods are essential for ensuring the safety and performance of electrical systems. Grounding refers to the connection of electrical systems to the earth, which helps limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines. Bonding refers to the connection of metal parts, such as enclosures and raceways, to establish electrical continuity and conductivity. Bonding ensures that there is an effective ground-fault current path that references back to ground and helps operate protective devices such as circuit breakers and fuses.

The National Electrical Code (NEC) provides guidelines for grounding and bonding of electrical systems in Article 250. The NEC requires different actions for grounded and ungrounded systems. For grounded systems, the NEC requires electrical system grounding, electrical equipment grounding, electrical equipment bonding, and bonding of electrically conductive materials. For ungrounded systems, the same actions are required except for electrical system grounding.

The NEC also specifies requirements for grounding electrodes, grounding conductors, bonding jumpers, equipment grounding conductors, methods of connection, and testing procedures . Some of these requirements include:

The NEC requires a minimum of two grounding electrodes unless one electrode has a resistance to earth less than 25 ohms.
The NEC permits ground rods to be spaced as little as 6 feet apart but recommends spacing them a minimum of twice the length of the rod apart.
The NEC requires that all metal parts that are likely to become energized shall be bonded together using a main bonding jumper or a system bonding jumper.
The NEC requires that all connections for grounding and bonding shall be made by exothermic welding; listed pressure connectors; listed clamps; listed fittings; or other listed means that ensure a permanent and effective connection without damaging conductors.

Grounding and bonding are not the same thing but work together to ensure the safety of electrical systems. It is important to follow the NEC guidelines for grounding and bonding methods. If you are unsure about the proper grounding method consult with a licensed electrician.

Box sizing

Always use the correct size box for the number and size of wires you're working with. The NEC provides guidelines for box sizing.

Installing cable without a clamp

Always use a cable clamp to secure the cable to the box. This will prevent the cable from being damaged and will also help to prevent electrical fires.

Insufficient electrical bonding

Make sure to follow the NEC guidelines for electrical bonding. This will help to prevent electrical shocks and fires.

Overcrowding holes with too many wires

Always use the correct size box for the number and size of wires you're working with. The NEC provides guidelines for box sizing.

Mixing line- and low-voltage wires

Never mix line- and low-voltage wires in the same box. This can cause electrical shocks and fires. Always keep them separated.

Not using a splice box when installing a new light fixture

Always use a splice box when installing a new light fixture. This will help to prevent electrical fires.

Putting HVAC ducts too close to carbon-monoxide and smoke detectors

Make sure to follow the manufacturer's guidelines for installing carbon-monoxide and smoke detectors. This will help to ensure that they function properly and will also help to prevent false alarms.