I got off the phone with Perfecto, he doesn't have email but he said he'd try to get in touch to take a look at this.
My take (deletions in red):
Advertencia. Desconecta energia el fuente antes de dar servicio.
Disconnect (ordering tense is a or e?) the source before servicing. Dar, give, is unnecessary. You're servicing, not giving servicing, IMO.
Advertencia. Este dispositivo equipo esta conectad? a mas de una fuente de corriente. Desconecte todas las fuentes de corriente antes de dar servicio.
I like mountain's use of "equipment" over "device". I didn't think poder looked right - directly translated it's "source to be able", which doesn't make sense. I asked Perfecto about poder over the phone and he suggested "fuerte de corriente", or "strength of current". I'd say "source of current" makes more sense, I couldn't remember the exact phrase you'd used, over the phone.
Advertencia. Cable amraillo o cableado con guia amerilla no es desenergizado al desconectar este panel.
I'll be perfectly honest, I haven't got a clue what you trying to say there, as an electrician reading it. How about...
Cuidado - El cable amarillo (or Los cables amarillos, whichever is more appropriate) o los alambres con rayas amarillos no son desenergizados cuando este panel esta desconectando.
Caution - The yellow cable (The yellow cables) or the conductors with yellow stripes are not deenergized when this panel is disconnected.
Edit: Come to think of it, I'm not convinced "desconectar" is a real word - all the switches I've ever seen have said "interuptor" on them. Perhaps that's a more appropriate word for this switch too.
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