There is a distinction between common property and communal property. For instance, your balcony is technically common property – in terms of who has responsibility for its maintenance – but that doesn’t mean every other owner is permitted to access it.
Even communal property like a swimming pool may be subject to restrictions on the hours you can use it. And common property areas such as the roof may have a complete ban on owners’ access.
The same applies to utilities – unless you have a legitimate reason for requiring access to fuse boxes or powerboards, then they should be off limits to most owners. Why? Because of potential dangers to owners and potential detriment to the rest of the scheme if anyone and everyone can go in there and start messing around.
That said, if you have a legitimate reason for requiring access, then the strata committee (or whatever it’s called in WA) should be able to allow it, subject to reasonable restrictions.