Mogul Base Lights Bulbs: What Are They?

This blog has been updated from its previous 2009 version

It’s about the larger base. Mogul (screw) base light bulbs or mogul base

bulbs have larger screw bases (E39) than the standard, medium (E26) screw base bulbs. In fact, the “39”Ā of E39 and “26”Ā of E26 each refer to the millimeter width of the respective screw bases (i.e., E39 base bulbs = 39 millimeters = 1.5 inches; and E26 base bulbs = 26 millimeters = 1.0 inch), and do not refer to the shapes of the light bulbs.

More power, more heat. Mogul base bulbs are made of cast porcelain to tolerate higher temperatures, making them ideal for industrial and commercial uses (e.g., power ratings of 250-1000 watts); in terms of technology, mogul base LED bulbs, mogul base compact fluorescent bulbs, and mogul base halogen, mercury vapor, metal halide, and high pressure sodium bulbs are available in the market.

“U” stands for mogul base. Selecting the correct size bulb can be confusing because light bulbs in general are available in different base sizes. All you have to remember when reading product descriptions is this: the “U” in, for example, M175/U/MED and MH1000/U/BT56, stand for mogul base. But if you happened to get a medium base bulb (E26) for your mogul base lamp (E39), the good news is that you can get a reducer to use the E26 light bulb on your E39 base bulb lamp; additionally, you can get a converter to use a 3-way E26 light bulb in a 3-way E39 base bulb lamp.

Shop now for LED mogul base lights>>>

Topstar 36W LED HID Corn Light CNE39-850-36P-M1-BP E39 Base 5000K
Topstar 36W LED HID Corn Light CNE39-850-36P-M1-BP E39 Base 5000K
Green Watt 60W LED HID Replacement Corn Lamp Mogul Base 5000K MYM-6M
Green Watt 60W LED HID Replacement Corn Lamp Mogul 5000K MYM-6M
Maxlite 200W 277V 5U Mogul Base CFL SKO200EA250 50K E39-277V
Maxlite 200W 277V 5U Mogul CFL SKO200EA250 50K E39-277V



37 thoughts on “Mogul Base Lights Bulbs: What Are They?

  1. michael m says:

    Is there a typo on the site or are there several mogule base sizes? The article starts off by defining E39 for Mogul & E26 for medium base, while later in the article E29 is also referred to as Moguul base.

  2. Conservation Mart says:

    Sorry for the confusion. Our mistake. E39 is Mogul Base, while an E29 base is known as the medium screw. Thanks for catching that!

  3. Howard says:

    In you article you indicate that a 3 way adapter is available for modul to medium bulbs. I have been looking for an ANSI E39D to E26D (three way bulb) adapter for two years. Please advise us of a source. Thanks

  4. clif mccormick says:

    Thanks for the article.

    Do you have a source for a CLF replacement for a 3-way 100/200/300 mogul base lamp? I have several antique lamps that take these old monster bulbs and I would love to update them, but do not want to give up 3-way capability.

    Thanks Again!

  5. Conservation Mart says:

    Clif, thanks for the feedback!

    Unfortunately, we don’t have any 3-way mogul base bulbs. The mogul base CFLs that we carry are all of the single-wattage variety.

  6. Richard Washburn says:

    You said that you only carry single wattage mogul base cfl bulbs. But do you know of a source for a 3 way mogul to d=reduce to a 3 way standard?

    “you can get a converter to use a 3-way E26 light bulb in a 3-way E39 base bulb lamp.”

  7. Conservation Mart says:

    Richard, we unfortunately do not have a list of stores selling these converters. We can say there are a number of retailers, primarily online, who sell them. We suggest doing a quick online search for them and a list of stores selling converters as well as the prices they are listed for will come up.

  8. Michael Masi says:

    The ONLY one I saw so far. Please advise if you find them cheaper.

  9. Lisa Maria says:

    I too am unable to locate 3-way mogul converter. Despite ongoing search I’ve had no luck.

  10. Fernando Urrutia says:

    So E29 is the “standard” base (Edison style) and the E39 is the Mogul, it’s there on the market a base that it’s on between this two sizes? I work on retail and on one time a customer was looking for a “big lamp” (Mercury Vapor) and he mentioned that the Mogul base was just too big, but the standard base on mercury vapor was way too small for his light fixture (personally I believe he was not setting the lamp straight on the socket and that was the problem, it’s hard to do it when you are up on a 20 ft ladder!)…

  11. Conservation Mart says:

    Hi Fernando,
    We aren’t aware of a bulb base in between those two. It could be that the bulb was custom made for that specific fixture.

  12. Linda Doll says:

    Please tell me more about “you can get a converter to use a 3-way E26 light bulb in a 3-way E39 base bulb lamp.”



  13. Conservation Mart says:

    Hi Linda!
    Your local hardware or home improvement store may carry an adapter that screws onto the base of a standard-sized (E26) base bulb that will allow it to be used in a fixture that is for use with a larger base (E39) bulb.

  14. Brian says:

    The local hardware stores sell adapters, but they are only 1-way. We are looking for 3-way adapters. That is the question šŸ™‚
    Anyone have any luck finding one?

  15. Mark Miller says:

    “U” stands for universal burn position, not mogul base… an MH175/U/MED lamp is actually a medium base…. that is what the MED in the lamp identification stands for

  16. Russ Baker says:

    All you have to remember when reading product descriptions is this: the ā€œUā€ in, for example, M175/U/MED and MH1000/U/BT56, stand for mogul base.
    The “U” stands for universal burning. which means the lamp will work when mounted either horizontally or vertically. the M175/U/MED is a medium based lamp. The MED means medium base.

  17. David taylor says:

    I have a M90 100 watt bulb and can only find a bulb with 4200k and lower.Can I use any other bulb in place of the m90?I’m looking for higher k.

  18. Conservation Mart says:

    Hi Tyler,
    An adapter should work. We don’t carry that particular kind of adapter, so we can’t guarantee that it will unfortunately.

  19. Tom Graven says:

    Can you use a single wattage mogul lamp in a 3-way mogul socket? I placed a single wattage mogul base lamp in a new mogul base 3-way socket and the bulb instantly burned out. Another time placed a single wattage mogul base bulb in the same socket, it tripped the breaker. The socket is wired correctly and a 3-way mogul base bulb works fine, Thanks

  20. Allan L'Heureux says:

    Can you use a 300 watt mogul base bulb in a garage? They are the clear glass variety.

  21. Allan L'Heureux says:

    Does a 300 watt mogul bulb use more power then a medium base 300 watt bulb? The mogul bulbs do not require a ballast. Thanks

  22. Conservation Mart says:

    The temperature of the bulb will depend on the type, and not the wattage. For example, a 300W LED or CFL will not get hot at all, whereas a 300W incandescent bulb will get considerably hot.

  23. Robert says:

    Do E39 mogul screw in bulbs have or need a ballast? I got a new bulb with a reducer but it will not work.

  24. paul m pleasant says:

    If it is a metal halide (MH) or high pressure sodium (HPS) bulb than yes, it requires a ballast. Most LED conversion lamps for these fixtures come with a built in ballast so they do not need an external one.

  25. Gerri Minton says:

    I have my grandmother’s old floor torch lamp. I remember it always having a 3 way bulb in it. I know that it was a large bulb with a large base. After reading all of the above posts I am terribly confused. This lamp is from the 1930’s. Any advice you can give me as to what type of bulb to buy would certainly be appreciated. It has a large glass shade that fits around the area where the bulb gets inserted so the glow of the bulb is cast towards the ceiling.
    Many thanks.

  26. Conservation Mart says:

    Hi Gerri! I would suggest looking up the fixture online, and seeing exactly the type of bulb it’s suited for.

  27. Robin says:

    did you get a replacement bulb? Home Depot carries the one that I use in my similar antique lamp, it’s by Phillips, it’s a Mogul base PS25 3-way; I
    love my (marble based/with metal accents) floor lamp..

    -I found your question when I was looking for a re-wire kit, as my lamp has recently stopped turning on, even with a bulb change…good luck!

  28. Terry says:

    I had to replace a ballast in a mercury Mogul Base E39 150W bulb fixture. I told the company I ordered the ballast from what I had and they sent a new ballast which was much smaller than the original ballast. I called the company back and he said it would be fine as long as it was 150 watt. I tested the light and it worked. Reassembled the fixture, tested again and it worked, however lasted about 3 days and quit. Could it be that the ballast sent was for a medium base bulb and that’s why it blew?

  29. Linda Kerth says:

    So, I have a standard extension cord in a coop, with a standard (medium) socket. I would like to install some heat this winter, but I am warned that it is really not safe in a coop to use a standard heat lamp. So I’d like to try a ceramic lamp for warmth, but not light — I’d like my chicken and ducks to sleep in a dark environment, but one kept above freezing, say a 4x6x8 shed at a minimum of 35-40 deg. with a natural day/night light. How can I adapt a standard base to a mogul one? Is there an adapter?

  30. Conservation Mart says:

    Hi Linda. There are adapters available to allow a standard base bulb into a mogul base fixture. Unfortunately, we don’t currently sell them on our site. However, check your local hardware store, and let them know what your specific requirements are. They may be able to recommend a fix for you.

  31. Conservation Mart says:

    Hi Terry. That is possible. To be sure, try contacting the manufacturer of the fixture, and let them know what’s been happening. They likely have a warranty period that you can take advantage of.

  32. Conservation Mart says:

    Hi Gordon. Yes, there are adapters available that will allow you to do this.

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