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Bakelite plastic electrical receptacle cover properly-installed (C) Daniel Friedman at InspectApedia.comElectrical Outlet Cover Plates
Types of electrical receptacle covers, fire & shock safety, durability

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Types of electrical receptacle faceplates or cover plates:

Here we review opinions of electricians and research authorities on the different types, materials, safety and performance of the face plates or cover plates used on electrical receptacles, popularly referred to as "wall plug outlets".

We list the common materials used for faceplates and compare features of durability, fire safety, and damage resistance of each. This is a companion article to our discussion of the argument about whether electrical receptacles should be installed "ground-up" or "ground-down" - exploring the argument that a metal faceplate may drop and short against the connectors of a wall plug.

This article series describes how to choose, locate, and wire an electrical receptacle in a home. Electrical receptacles (also called electrical outlets or "plugs" or "sockets") are simple devices that are easy to install, but there are details to get right if you want to be safe.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

Receptacle Box Cover Plates

Metal & nylon receptacle covers resist breakage, but metal is electrically conductive

However nylon switch and receptacle cover plates, currently the most-widely-sold form, are very flexible and will not crack when flexed by tightening the screw. Below are some examples of just a few of the many different materials used to produce electrical outlet covers.

Brass plated steel receptacle cover - Amarelle (C) Daniel Friedman at InspectApedia.com Amarelle Steel receptacle cover, painted (C) Daniel Friedman at InspectApedia.com Nylon receptacle cover - Leviton (C) Daniel Friedman at InspectApedia.com Bakelite electrical receptacle cover - Leviton (C) Daniel Friedman at InspectApedia.com

Of the four receptacle covers shown above, the first three (brass plated steel, painted steel, and nylon) will not be easily damaged nor broken by over-tightening the center mounting screw.

Bakelite receptacle covers are easily damaged or broken by an over-tightened mounting screw and possibly also by impact.

Even a rather high-torqued faceplate mounting screw won't break a typical plastic receptacle or switch cover unless the device itself (the receptacle or switch) is also recessed into the electrical box or below the plane of the wall surface.

Fragile Receptacle or Switch Faceplates Easily Damaged / Broken

Below: examples of fragile faceplates: glass/mirror receptacle cover, a ceramic receptacle cover, and a Carrara marble electrical receptacle cover.

Glass mirror electrical wall outlet cover plate (C) InspectApedia.com Ceramic electrical receptacle faceplate (C) InspectApedia.com Carrara marble electrical receptacle cover plate (C) InspectApedia.com

Watch out: particularly because I have often found glass and marble receptacle covers installed in bathrooms into which mirrors or marble wall coverings were installed after the original construction and electrical work, the electrical device, switch or receptacle is very often recessed in the wall. It is precisely this case that invites a broken cover plate when the cover screws are tightened during installation.

See ELECTRICAL BOX RECESSED DEPTH IN WALLS for details on how to avoid creating that problem or how to fix it by bringing the device forward to the plane of the finished wall surface before the cover plate is installed.

More-Easily-Ignited Combustible Receptacle Covers / Faceplates

Watch out: in addition to the fragility of some receptacle covers (bakelite, ceramic, glass, marble) some are also likely to be more-combustible than others, such as wood and painted wood and possibly some of the plastic covers.

Wood electrical receptacle faceplate (C) InspectApedia.com Painted wood receptacle faceplate (C) InspectApedia.com

Above: natural wood and a painted wood electrical receptacle faceplates. These faceplates are easily split at the mounting screw if the receptacle is recessed in the wall, and they are also more-combustible than some other faceplate materials listed above.

Example Receptacle / Switch Cover Identification Marks

Leviton stamp inside of an electrical receptacle cover or faceplate (C) InspectApedia.com

Here we show Eagle, Leviton, and Sierra Electric stamps found on the interior side of some plastic receptacle and switch faceplates.

Some faceplates used on switches and receptacles, at least among molded plastic models, will bear the manufacturer's stamp as well as UL and other certification stamps on the inside face of the cover plate.

Sierra receptacle cover faceplate identification at InspectApedia.com

Other faceplates made of wood, metal, ceramic, marble, nylon etc. may not be so marked.

Eagle bakelite receptacle faceplate identification (C) InspectApedia.com

Specialty Receptacle Faceplates

Special-purpose electrical receptacle faceplates include twist-lock covers, tamper-proof covers, weather-proof covers and other uses that we have not addressed. Contact us if you need that information.

Install Receptacles Ground-Up where Metal Covers are Required

Loose electrical receptacle cover can fall on to wall plug contacts (C) Danie Friedman at InspectApedia.comReader Comment: ground-up avoids short if metal receptacle cover plate slips down

Some readers have suggested a more-subtle hazard that we will evaluate: during plug removal or if the plug is not fully inserted into the receptacle, a receptacle's metal faceplate could slide down and contact the hot and neutral connectors.

2018/08/14 Tom west said:

In cases where the outlet cover plate is metallic and held by the typical single screw, mounting the ground pin up prevents the cover plate from dropping across the phase and neutral conductors.

Of course, the cover plate screw would have to somehow be lost, but that never happens, right?

Reply: Yes, a metal electrical receptacle cover can fall and short circuit across wall plug connectors

That's an interesting observation, Tom. Thank you for the suggestion and for prompting me to spend a couple of days exploring this safety concern.

In our photo above I have completely-removed the receptacle mounting plate screw and I have pulled out the wall plug to afford room for the cover plate to slip down into contact with the plug connecting spades.

Watch out: however during the removal or un-plugging of a wall plug it is more-likely that the cover plate could drop, shorting between the hot and neutral plug connectors.

However when a wall plug remains fully inserted, a loose and falling metal receptacle cover cannot easily contact the plug's connectors.

Below I include a close-up image showing the edge of the receptacle cover plate in contact with the plug connectors - a condition that would be likely to have created some exciting sparks until the circuit breaker or fuse tripped or blew.

Below you can see that without a mounting screw and while a wall plug has been partly withdrawn from the electrical receptacle, the cover plate can fall down into contact with the plug connectors.

Fallen electrical outlet cover plate contacts the wall plug connectors - this would cause a short circuit if a metal cover plate were used (C) Daniel Friedman at InspectApedia.com

Watch out: don't try this experiment yourself as you could be shocked, burned, or killed.

Because I made these photos in our lab where fires and shock injuries are discouraged, I used a non-conductive bakelite plastic receptacle cover to demonstrate how a receptacle cover could contact wall plug connectors.

Probability of a Receptacle Cover Falling into Contact with Wall Plug Terminals

OPINION: Shorting the hot and neutral spaces of a wall plug by the metal receptacle cover and a subsequent possible shock or fire hazard could indeed occur, but with probably only with difficulty as a number of conditions have to all be present. Those include at least the following:

Loose receptacle cover stays in place if screw is present (C) Daniel Friedman at InspectApedia.com

The event is as you suggest possible, though I suspect, not very likely to be a commonly-reported electrical failure.

How Easily is the Cover Plate Screw Removed or Lost?

It depends.

Plastic duplex electrical receptacle cover screw using a plastic screw retainer prevents screw loss (C) Daniel Friedman at InspectApedia.com

Above: this Leviton™ receptacle cover is sold with the receptacle cover retaining screw pre-installed and retained in the cover plate screw opening by a plastic clip.

Even from a single manufacturer, some receptacle and switch cover plates are sold pre-packaged without and others with with the retaining screw held in place by a paper or plastic gasket.

Electrical device cover plate screw (C) Daniel Friedman at InspectApedia.com Plastic retainer clip on an electrical receptacle or switch cover screw (C) Daniel Friedman at InspectApedia.com

Above: some Leviton™ plastic receptacle covers are sold with the plastic screw retainer shown above. It is actually difficult to remove the retainer, and normally it is simply left in place as the cover is installed.

In this case even if the screw is completely loosened from the threaded receiving opening on the electrical receptacle or switch, the screw remains attached to the cover plate and it tends to remain inserted into the receiving opening enough that the plate does not fall down.

However other receptacle and switch cover screws are sold loose in the package with the cover plate and do not include this retainer. Those screws can be loosened completely and can fall out of the cover plate entirely.

The example below, a Leviton™ quad- receptacle cover, removed from its plastic package, shows that the screws are included loose, without the retainer clip.

Receptacle cover screws do not always include the plastic or paper retainer clip (C) Daniel Friedman at InspectApedia.com

There's a no-win problem for the companies packaging receptacle and switch covers with screws. If the screws are packaged pre-inserted using a retainer clip the end of the screw tends to poke a hole in the thin cellophane or plastic wrapping the cover - in that case the screw can be lost or the cover package torn, losing its bar code needed for pricing.

On the other hand if the screws are packaged loose in the cover wrapper, they too can be even more-easily lost if the wrapper is damaged or torn during distribution, stocking, or sale.

In my OPINION the plastic retainer clips provide an additional safety feature that prevents the screw loss after original installation, thus preventing the cover plate from falling down or off.

Research Data on Metal Receptacle Cover Shorts to Plug Connectors: Not Found

On 8/14/18 we did both a general search and more-formal research for scholarly articles, codes, standards or wiring practices on electrical failures and short circuits, electrical safety, and among patents for metal electrical receptacle covers, using the terms such as:

metal electrical receptacle cover plate short circuit safety hazard and also metal receptacle cover hazards or short circuits - in various combinations -

without finding a single research article, electrical code, nor electrical standard that has discussed on this hazard.

As you suggest, absence of reports of such failures doesn't mean they can't occur, but it probably means the occurrence is rare and probably not, alone, sufficient to require ground-pin-up installations of electrical receptacles.

If you have found any field reports, standards, or codes that describe this hazard as more than theoretical that would be very valuable information that we should add here.

Preferences for non-conductive receptacle covers

Except for special situations where durability is an issue, we advise consumers and electricians to install plastic receptacle and light switch covers as a generally more-safe device, regardless of which way the ground pin hole has been placed.

That reduces the metal surface at an electrical receptacle that could possibly become live and that might be touched (by a child, for example) to just the area of the receptacle cover screw head itself.

Preferences for metal receptacle covers & switch plates?

Broken plastic receptacle cover - Eagle (C) Daniel Friedman at InspectApedia.comInteresting side note: vendors of metal switch and receptacle plates promote the "improved safety" of metal plates by noting that over-tightening the screw of a plastic switch plate or receptacle cover can cause it to crack, split, break. (Kyle Switch Plates, retrieved 2018/08/14 kyleswitchplates.com )

Our photo shows a broken bakelite or other rigid-plastic electrical receptacle cover.

I simply twisted the cover in my hands to see how it would fracture. This is not a normal receptacle cover break since the most-common breakage is at the screw hole alone.

So yes, Kyle, a metal receptacle cover manufacturer, is right that plastic receptacle covers can crack, split, or break.

Really? Well yes and no.

Bakelite or other hard-plastic receptacle and switch plates, marble receptacle covers, and also mirrored glass receptacle cover and switch plates will crack or even break when the screw(s) is (are) tightened, particularly if the switch or receptacle is recessed in the electrical box such that tightening the screw pulls the switch or receptacle cover plate inwards more than a fraction of an inch.

Requirement for Receptacle Covers to Resist Damage: US National Electrical Code & OSHA Guidance

Article 110.27(B):

(B) Prevent Physical Damage. In locations where electrical equipment is likely to be exposed to physical damage, enclosures or guards shall be so arranged and of such strength as to prevent such damage.

US OSHA guidelines on cover plate requirements for receptacles

Question: For workers engaged in construction activities, does 29 CFR 1926.405(j)(1)(i) require plastic switch plates or receptacle covers and non-conductive (e.g., nylon) screws to hold those switch plates or covers on?

Answer: No.

Title 29 CFR 1926.405(j)(1)(i) states:

(j) Equipment for general use-

(1) Lighting fixtures, lampholders, rosettes, and receptacles-

(i) Live parts. Fixtures, lampholders, lamps, rosettes, and receptacles shall have no live parts normally exposed to employee contact. However, rosettes and cleat-type lampholders and receptacles located at least 8 feet (2.44 m) above the floor may have exposed parts. [Emphasis added.]

The provision does not specifically state that switch plates or receptacle covers be made of non-conductive material or that the screws to hold those switch plates or covers on be non-conductive, and there is no indication in the preamble to the standard reflecting an intent to create such an obligation.

Switch plates and receptacle covers are designed to prevent people from coming into contact with (that is, touching) properly installed live electrical parts that are inside the switch/receptacle box. When the live parts inside the box are properly installed and the cover is on, those parts will not be "normally exposed to employee contact."

Therefore, under §1926.405(j)(1)(i), covers are not required to provide an insulating barrier in the event a live part inside the box comes in contact with the back of the cover. Similarly, there is no requirement that the screws that affix the covers to the box be of a non-conductive material.1

Note that, if a faulty switch or receptacle has caused the cover or screws to become energized, construction employees working in proximity to it must be protected. Title 29 CFR 1926.416(a)(1) states:

No employer shall permit an employee to work in such proximity to any part of an electric power circuit that the employee could contact the electric power circuit in the course of work, unless the employee is protected against electric shock by de energizing the circuit and grounding it or by guarding it effectively by insulation or other means. - PLASTIC vs METAL SWITCH / RECEPTACLE COVERS - OSHA [PDF] retrieved 2018/08/14, original source: www.osha.gov/laws-regs/standardinterpretations/2004-09-17

Research on Electrical Receptacle Cover Types, Materials, Safety

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