How do you connect a fluorescent tube? 

You have andother way for connect a fluorescent tube in a magnetic ballast, or for connect in series or parallel?
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With switch start, you connect it just like your example (the attached picture). With HF ballast, you follow the wiring diagram on the label.

If you connect two lamps in series on a single choke ballast, you need a starter loop for each lamp. You can only do so on mains above 200V, however. For this to work, you will need 120V starters even though the mains are above 200 V.

If you connect two lamps in parallel (each having a starter loop) then only one will strike. This concept is sometimes used to extend the period between relamping visits.

Thanks!

A diagram of the circuit (note: this is a pre-heat style circuit with a starter)

I think 2x 4W T5 might be able to work in series on 120V. However there are no suitable starters made (this would need "60V" starters)

In Instant Start setup, any number of FL tubes can be connected in series up to the max arc voltage the ballast can provide. Connect 1 or 2 pins at the tube end based on how close the supplied current is to the lamp's nominal current (1 pin is preferrable when the tube is underdriven)