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I'm working on a thing in which I mount a few pounds of weight to one of those light-bulb-to-wall-socket adapters and I'm curious if there's a posted weight limit on hanging something from just the light bulb socket itself.

This is not really for a home improvement thing; it's a work project, but the application seems relevant to this stack's topic.

  • There probably isn't, and the actual capacity will vary by product, but most would probably hold between 10 and 50 lbs. before catastrophic failure. – isherwood Aug 7 '17 at 18:28
  • Practically speaking, you see various lamp shades, etc, that weigh in the tens of pounds and which are supported entirely by the socket. – Hot Licks Aug 8 '17 at 2:04
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    @AndyT -- I have a light-bulb to wall-socket adapter in my basement, and it's quite safe even though it isn't grounded as both the things plugged into it are Class II (i.e. double insulated) – ThreePhaseEel Aug 8 '17 at 11:38
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    @AndyT -- a grounded appliance won't plug into an ungrounded plug without an addapter, correct – ThreePhaseEel Aug 8 '17 at 22:20
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    @ThreePhaseEel: us Brits are impeded in our understanding of your ways. Our plugs are the same whether earthed or not (if not then the third pin just isn't connected, but it still has to be there because our sockets won't accept the live pin unless the earth pin is inserted), and there's no such thing as an unearthed socket (barring, of course, the same kind of incompetence that would result in an ungrounded three-pin socket in the US). Or to be precise, the only unearthed sockets are shaver type. – Steve Jessop Aug 9 '17 at 2:11
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Not a great idea.

  1. Electrical devices are designed and approved to be used unmodified. Adding parts or using them other than as intended voids the UL listing and, more importantly, poses risks of fire or electrocution.

  2. Attaching something to a plug in device at or near the plug runs the specific risk of shorting out the spade terminals, risking the above noted fire or electrocution.

  3. The weight that could be supported (but shouldn't be) would depend on whether the plug in socked was inserted horizontally or vertically (hanging down), the latter being much less reliable than the former, which is also not reliable.

  4. The actual strength of the hold is a factor of the tension created by the contact points within the wall socket itself. This is variable across brands, types of outlets, and changes over time and usage. It is impossible to predict whether a socket will hold a regular plug, let alone extra weight attached to a device that already puts a downward strain on the grip. Another reason not to do it.

  5. Finally, plug in lamps are varied in their quality and hence their strength, again making a load prediction nigh on impossible.

  6. Don't do it.

  • I agree with @bib the socket is only listed for the type and size lamp it was made for. Some fixtures may be able to support a lamp and shade but some barely exceed the lamp. Fire marshal inspection or an electrical inspector may write a violation. + – Ed Beal Aug 7 '17 at 18:59
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The National Electrical Code is quite specific about the listing requirements and the weight of a luminaire attached to the screwshell of a lampholder. Which is what your question indicates.

Here are the pertinent sections:

410.6 Listing Required. All luminaires and lampholders shall be listed.

The definition of listed follows:

Listed. Equipment, materials, or services included in a list published by an organization that is acceptable to the authority having jurisdiction and concerned with evaluation of products or services, that maintains periodic inspection of production of listed equipment or materials or periodic evaluation of services, and whose listing states that either the equipment, material, or service meets appropriate des-ignated standards or has been tested and found suitable for a specified purpose.

UL (Underwiters Laboratories) and the CSA (Canadian Standards Association) are two examples of listing agencies that are normally acceptable to the AHJ. But they are not the only listing agencies in the world.

IV. Luminaire Supports

410.30 Supports.

(A) General. Luminaires and lampholders shall be securely supported. A luminaire that weighs more than 3 kg (6 lb) or exceeds 400 mm (16 in.) in any dimension shall not be supported by the screw shell of a lampholder.

So, field modified or home made luminaires would normally be considered a violation of the NEC.

You should find a different way to do this especially in a work environment that would expose the company to liability.

  • FYI the reason I call US law "complicated" is that what you quote is quite clear -- but it isn't law. Most jurisdictions incorporate it into law, or base their own regs on it. That is the complicated part. – Harper Aug 8 '17 at 14:52
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It's illegal, unless...

You are not allowed to use an electrical product in any way contrary with its labeling and instructions.

You are also not allowed to use any electrical equipment as a support structure for ”something" e.g. Anything else. The most common blunder is hanging phone, internet or thermostat cable off Romex or conduit. I just removed some of that from a brand new furnace installation. But it also applies to using a light socket or junction box to hang a mobile, pinata, model airplane, etc.

A luminaire (light fixture/assembly) is the exception. It is allowed to hang a luminaire off a junction box, if it weighs less than six pounds. This weight can also be hung off an Edison screw base in USA (NEC 410.30A), but that seems unlikely -- far more likely you would mount it to the junction box.

A heavier luminaire can be hung off a special junction box made for that purpose.

An even more special junction box is made for ceiling fans. A common violation is hanging a ceiling fan from a ceiling box which is not listed for ceiling fans. Aside from the unexpected weight, the problem is also vibration - I've never seen a fan that was balanced, and the vibration will eventually pry the nails out or crack the box.


The question of "leeeegal" gets super pedantic super fast due to the complexities of (especially US) law, and quickly devolves into "what do I think I can get away with" - this amounts to trying to make a simple thing complicated, with a motivation most foul: trying to cheat safety. So let us cleave this Gordian knot with a more basic question: Is there any competent regulatory agency in the world which on fair contemplation, chooses to explicitly authorize general use of electrical equipment contrary to its listing, labeling and instructions? I assert you will not.

  • So when would a product like this be legal? It is UL listed, but does not come with a safety sheet listing the max weight. – StrongBad Aug 7 '17 at 22:33
  • Sometimes UL listings are fraudulent. Without other documentation, you can only assume it is built for the obvious usage, which is carrying the weight of a light bulb and about 6 inches of cord, presuming the cord is looped or tied somewhere appropriate to carry the rest of its weight. – Harper Aug 7 '17 at 22:59
  • I've been using a dead fluorescent ballast as a door stop for a few years now. Am I going to jail for this? – Eric Urban Aug 8 '17 at 1:18
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    "It's illegal" - As there is no specific country listed in either that statement or the question, this is debatable. Would you mind adding a qualifier (ie, at least in [country])? – Shadow Aug 8 '17 at 1:38
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    @StrongBad see the 6 pound restriction in the Code I posted. Anything exceeding 6 pounds attached to the screwshell would be a violation. Otherwise that device would be considered "legal" by the NEC. – ArchonOSX Aug 8 '17 at 6:55
0

This is crazy, don't do it. Don't even ask whether it may "work".

If I understand "light-bulb-to-wall-socket adapter" corrently, you are planning to screw something that isn't anything like a lightbulb into one of these and expect it to carry a weight. At work, to make things worse.

First, is it immediately obvious that this isn't the greatest idea ever. The adapter is neither meant/designed to be used that way, nor approved (on the contrary!), nor likely to function reliably as intended by you. Also, the mere mention of "high voltage" should raise a red flag in everybody's head, even without the explicit absence of proper grounding or safety breakers such as is necessary for anything that has a conductive surface and is connected to high voltage of sorts.

Second, even assuming that you don't care much about the previous paragraph because, hey, what can happen, and your boss said it's OK... you are (intentionally) violating workplace security. If nothing else, this can mean major trouble involving a big-$$$ fine for your employer (and you being fired) in case of an audit. It can also mean that the casualty insurance may refuse to pay in case someone gets hurt directly or indirectly by, or only just nearby your thingie. The workplace as such is not approved with such an unapproved construct at it or nearby. That's a huge thing.

Third, you are personally liable (civil action) in case someone gets injured or killed at your office, or in case the whole shit burns down. Do you really want to discuss about regress on a 2-digit million sum with a fire insurance?

  • You could improve your answer by elaborating on the language and shorten the text to real facts. – Jonas Stein Aug 8 '17 at 21:43

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