# KiCad: Power with hierarchical sheets

I just started trying to use KiCad (complete newbie), and I have a very basic question about using power inputs with hierarchical sheets.

Let's say I want a single LED on a hierarchical sheet, while my main sheet simply contains a battery.

Should I use hierarchical labels to connect power from the main sheet to my hierarchical sheet, or is there another way?

For instance, the main sheet:

And the hierarchical sheet:

Is this the correct solution? I initially tried to used the +9v and GND elements in my hierarchical sheets (many of them in a single sheet), but KiCad complains that some of them are not driven.

I found lots of topics discussing this, but nothing I can really understand, nor related to hierarchical sheets.

If I need to use hierarchical labels for connecting power, then when should I use +9v and GND?

• Technically, using +9v and GND ought to work. I have done so myself using the VCC and GND What is the error you're getting? – chamod Aug 23 '15 at 17:49
• It says it is not driven. Does it mean I need to add a power flag to at least one +9v and GND in the hierarchical sheet? – Macmade Aug 23 '15 at 17:51
• In KiCad the power symbols are global throughout all the sheets. So if you add a battery in the main sheet and connect it to +9v and GND and then, did the same in the hierarchical sheet, KiCad will connect the nets when creating the net list. You don't have to use the hierarchical labels that way. – chamod Aug 23 '15 at 17:55
• But then this requires a power flag in the hierarchical sheet right? – Macmade Aug 23 '15 at 17:59
• As far as I know, you don't necessarily have to use a power flag. But if you don't, the ERC won't like it. – chamod Aug 23 '15 at 18:10