What does T8 mean in lighting?

[Rednadnerb]

T4, T8?

The man at B&Q said it was to do with the width of the tube. Is it the bigger the number the thicker the tube? and what does the T stand for? we couldn't figure it out.

Thanks

Brendan.

[Andy Cap]

Apparently, it's the number of 1/8ths inch in the diameter.

[Adrian]

Rednadnerb gurgled happily, sounding much like they were saying:

Wild guess - T-for-Tube?

[Andrew Gabriel]

Yes, it's the tube diameter in 1/8ths of an inch, in UK and US. In other parts of Europe, the T number is sometimes in mm, and sometimes in 1/8th inch, so you have to be a bit careful about which is intended, although there's rarely confusion.

[meow2222]

[Rednadnerb]

Perfect. Thanks.