Lamp Basics: A Plain-English Guide, One Topic at a Time

Lamp Stuff

Lamps are among the simplest electrical things in a home, and yet most of us know surprisingly little about them. What is the part with the switch called? Why does the label say “max 60W” when the bulb box says “equivalent to 100W”? Is a salt lamp doing anything for the air? This series takes one lamp topic at a time and explains it in plain English, with every claim traced to a named source.

It is aimed at people who own lamps, not at electricians. It will not teach you to rewire anything, and in a few places it deliberately says “stop here and get someone qualified”. What it will do is help you understand what you are looking at, read the labels, avoid the common mistakes, and know which advice you can trust.

A table lamp with a pale cone-shaped shade and a cream-coloured vase-shaped base, standing on a shiny surface, with a bright patch of sunlight and a sharp shadow of the shade on the wall behind it.

Image: A table lamp with a cream lampshade, lit by sunlight by LoMit, CC BY-SA 4.0, via Wikimedia Commons.

Where to start

If you are not sure which post you need, this is how I would pick:

  • My lamp will not light. Start with the troubleshooting post, which puts the checks in a safe order.
  • I need a new bulb and the shop has fifty kinds. Read the bulb-base post and then the lumens post.
  • I want to know what the parts are called. The anatomy post names them from plug to finial.
  • I am choosing or replacing a shade. The lampshade post covers shapes, fitters and sizing.
  • The cord or plug looks worn. Go to the cord-and-plug post.
  • I am curious about Tiffany lamps or salt lamps. Each has its own post, with the history in one and the evidence in the other.

The series at a glance

The posts do not need to be read in order, but each one links to its neighbours at the end, under “Where to go next”.

Five safety habits that run through the series

These come up again and again in the sources I read, so I will put them in one place.

  1. Unplug before you touch. Electrical Safety First, a UK electrical-safety charity, says not to change a bulb while the lamp is on: turn it off, unplug it and wait a few minutes for the bulb to cool. The Guardian’s how-to says never to work on an appliance that is plugged in.
  2. Respect the maximum-wattage label. A New York State fire-safety bulletin says that exceeding the maximum wattage can easily melt the shade or degrade the wiring. If your lamp gives no limit, the Consumer Product Safety Commission (CPSC) says to use 60 watts or less.
  3. Replace damaged cords. The CPSC’s Home Electrical Safety Checklist says to replace frayed or cracked cords, including on lamps, and not to put furniture on cords, wrap them tightly or fasten them with staples.
  4. Keep heat away from things that burn. Electrical Safety First says to keep lamps away from curtains, paper, bedding and other flammable items. A CPSC evaluation of lighting-product incidents found 79 in which outside factors may have contributed, such as a lamp knocked over or excessive wattage, and 40 of those involved bulb heat igniting nearby curtains, clothes or bedding.
  5. Never defeat the ground pin. Both the CPSC and Wikipedia (quoting the Electrical Safety Foundation International) say not to break the ground pin from a three-prong plug.
A lamp with a dark, pleated drum shade glowing from inside and a stack of chrome balls as its base, standing on a white and wooden bedside cabinet with the thin cord trailing behind it.

Image: A chrome bedside table lamp on a nightstand by PatongHarbor, CC BY-SA 4.0, via Wikimedia Commons.

A tiny glossary

  • Luminaire: the technical word for the whole lighting device. In technical usage, per Wikipedia, “lamp” means the light source, which most of us call the bulb.
  • Lumen: the unit of light output. ENERGY STAR says brightness is measured in lumens, not watts.
  • E26, E12, E27: screw-base sizes. The number is the thread diameter in millimetres, according to Wikipedia.
  • Harp, spider and finial: the metal frame that holds a shade, the shade’s own fitting, and the cap that holds it on.
  • Polarized plug: a two-blade plug with one blade wider than the other, so it can only go in one way round.

How this series was put together

I wrote each post from sources I actually opened: government safety agencies and the Department of Energy, a state fire-safety bulletin, a university extension bulletin, a UK electrical-safety charity, two museum writers on Tiffany, a clinic’s patient-information article, a published research abstract, news and magazine how-tos, and Wikipedia. Each post ends with a list of the sources it used, and each opinion of my own is marked as “my own suggestion” or “my own reading”.

A few honest caveats:

  • Some of the sources are dated. The University of Florida bulletin is from 2002, revised in 2005, and the CPSC lighting evaluation is from 2007. They describe a world of incandescent and compact fluorescent bulbs. Where that matters, I say so.
  • Some are British. The Guardian article and Electrical Safety First are UK sources, with UK plugs and wire colours. I use them for general principles and say when a detail is UK-only.
  • Some figures are second-hand. Where a figure comes through Wikipedia from another body, I say that it does.
  • Sources sometimes disagree, for example on how big a lampshade should be or how many women worked in Tiffany’s glass-cutting department. I show both rather than choosing quietly.
  • I give no prices and recommend no brands. If you want a specific product, that is a separate question.

The photographs are real, freely licensed pictures from Wikimedia Commons, each with a credit line under it. Some show lamps from other countries, which I note where it matters.

A tall silver floor lamp on a round foot, with a white glass bowl on top and a thin bendable reading arm with a small shade halfway up, standing against a cream wall; its cord runs across the carpet.

Image: A floor lamp with a bowl-shaped shade and a small reading arm by FASTILY, CC BY-SA 4.0, via Wikimedia Commons.

Where to go next

The quickest useful next step for most readers is the troubleshooting post, because it uses ideas from most of the others. The anatomy post is the best companion to it. The lumens post is the one I would read before the next time you buy bulbs.

Sources