Frequent question: Are metal electrical boxes better than plastic?

What are some advantages for using metal box over plastic?

Metals generally provide the following advantages over plastic fabrication:

  • Heat resistance: Metals typically have a higher melting-point and are less likely to degrade under elevated temperatures.
  • Improved strength: Metal grades tend to be stronger, harder, and more durable than their plastic counterparts.

What’s the difference between plastic and metal electrical boxes?

Plastic boxes are nonconductive, which means they won’t conduct electricity if they’re touched by a live wire. … By contrast, metal boxes, which are conductive, must be grounded to the circuit grounding system, usually with a short wire called a pigtail that connects the box to the circuit’s ground wire(s).

Do plastic electrical boxes need to be grounded?

Because they are plastic, there is no need to attach a ground wire to it. … Since it is made of a non-conductive material, switches and outlets cannot short out if they touch the side of the box. Plastic boxes usually come with tapped screw holes for easy attachment of switches and outlets.

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Do metal boxes need to be grounded?

ALL METAL boxes, conduit, etc used in an electrical system needs to be grounded.

What are the disadvantages of using metal?


  • Iron and steel can rust, severely weakening the structure.
  • The exploitation of metal ores to extract metal causes pollution and uses up the Earth’s limited resources.
  • Metals are more expensive than other materials such as concrete.

Is plastic more durable than metal?

Metal has a higher tensile strength than plastic. Stainless steel is durable and easy to clean.

Can I use a metal cover on a plastic electrical box?

You certainly can use metal or platic covers on plastic boxes. You need to make sure all wires are capped in the box….and you should not mix low voltage wires with line voltage in the same box.

Can I use metal boxes with PVC conduit?

Metal or plastic boxes can be used with nonmetallic conduit. Always run a ground wire when using PVC conduit.

Can you use a junction box to extend wiring?

You can definitely use a junction box to extend your wiring. To do this, start by turning off the power. Then inspect the place and cut the required openings. Next, position the wires and adjust the box to pass the wires through.

Can a junction box be inside a wall?

Junction boxes must be installed where they are always accessible; never install a junction box in a concealed wall or ceiling space where the box cannot be accessed in the future. Junction boxes also must be covered with solid covers with no holes.

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Can you ground a plastic junction box?

Plastic boxes cannot be grounded in the same way. But it’s still necessary to bring the equipment-grounding conductor into the enclosure to ground devices such as switches and receptacles. Connect the bare or green wire directly to the green screw on the device.

What happens if metal box is not grounded?

A grounded metal box is important to have as it sends the electricity through the ground to the breaker box that is also grounded. Surges in the electricity a box that is not grounded allows the electricity to go where it wants to. This is not a good thing and can cause electrocution or fire.

Can you ground a wire to any metal?

No, you do not have to attach a grounding wire directly to the metal enclosure if you are just using it as a pull point and you are otherwise grounding it using continuous runs of EMT.

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