This is because e26 bulb bases are assumed to only receive voltages up to 120v ac and not 240v ac.
E26 vs e27 bulb base.
The only difference is the voltage light bulbs that are 120 240volt.
Thus a e26 has a 26 mm base diameter.
Socket e26 stands for 26mm and the e27 for 27 mm in diameter.
Photo of the relative internal sizes of the sockets.
The e27 is the european variant and is rated at 220 volts.
E26 stands for 26mm and the e27 for 27 mm in diameter.
So for an e26 bulb the diameter of the base is 26 mm while the e27 has a base diameter of 27 mm.
It is easy to put an e26 bulb into an e27 socket.
The e26 is rated at 120 volts.
The only difference is the voltage.
The number following the e indicates the size in mm of the external thread screw.
The same size as a standard a19 bulb.
However an e26 bulb can fit in e27 base and an e27 bulb can fit in e26 base without problem.
You may see low cost led bulbs using an e27 base on ebay and amazon from foreign suppliers.
Samples of bulbs with these bases.
Those two standards are interchangeable meaning a us e26 will fit a european e27 base and e27 will fit in an e26 base.
E39 north america e40 goliath es in europe.
For more information about bulb shapes be sure to read more here.
Those two standards are interchangeable meaning a us e26 will fit a european e27 base and e27 will fit in a e26 base.
E26 is 26 mm and the e27 is 27 mm diameter.
The e26 is the standard 120 volt american base.
The european variant the e27 is rated at 240 volts.
If you have a 240 volt incandescent vintage bulb you are able to use them in the us where the voltage is 120.