Can anyone tell me a way to have a debris that can only be opened when the power is on.

Thanks

But this lets you buy the door with the electricity off.
I have a similar script in my map. I use two triggers, one for the hint and other for the door.
My code is something like:

trig = getEnt( "DOOR_TARGETNAME","target" );
hint = getEnt( "TRIGGER_TARGETNAME","targetname" );
trig trigger_off();
hint setHintString( "POWER STUFF" );
flag_wait( "electricity_on" );
trig trigger_on();
hint trigger_off();

This works well, but I'm sure there are better ways to do it.

But this lets you buy the door with the electricity off.
I have a similar script in my map. I use two triggers, one for the hint and other for the door.
My code is something like:

trig = getEnt( "DOOR_TARGETNAME","target" );
hint = getEnt( "TRIGGER_TARGETNAME","targetname" );
trig trigger_off();
hint setHintString( "POWER STUFF" );
flag_wait( "electricity_on" );
trig trigger_on();
hint trigger_off();

This works well, but I'm sure there are better ways to do it.

flag_wait( "electricity_on" ); // WILL FREEZE HERE TILL POWER ON
trig setHintString("press and blabla to open");
trig waittill("trigger", player); // SO COULDNT POSSIBLY DO THIS

No the method he posted first is fine

Ahms. Ok. My fault.
I tested it making a debris (with the targetname - zombie_debris) KVPs and it let me buy the door. But without this targetname it should work then.

Thanks all

If you do it this way, and set the hintstring twice, you should use the hintstring from the perks so your not adding another hintstring towards the limit.

SetHintString( &"ZOMBIE_FLAMES_UNAVAILABLE" );

You could also edit your zombiemode_blockers_new.gsc where your debris is handled.
Modifying the debris_init() like this should work:

debris_init()
{
	cost = 1000;
	if( IsDefined( self.zombie_cost ) )
	{
		cost = self.zombie_cost;
	}
	self SetCursorHint( "HINT_NOICON" );
	if( isdefined (self.script_flag)  && !IsDefined( level.flag[self.script_flag] ) )
	{
		flag_init( self.script_flag ); 
	}
	if(isDefined(self.script_noteworthy) && self.script_noteworthy == "electric_door")
	{
		self set_door_unusable()
		flag_wait( "electricity_on" );
	}
	self set_hint_string( self, "default_buy_debris_" + cost );
	self thread debris_think(); 
}

Of course this would require you made a kvp script_noteworthy = "electric_door" on the trigger

If you do it this way, and set the hintstring twice, you should use the hintstring from the perks so your not adding another hintstring towards the limit.

SetHintString( &"ZOMBIE_FLAMES_UNAVAILABLE" );

You could also edit your zombiemode_blockers_new.gsc where your debris is handled.
Modifying the debris_init() like this should work:

debris_init()
{
	cost = 1000;
	if( IsDefined( self.zombie_cost ) )
	{
		cost = self.zombie_cost;
	}
	self SetCursorHint( "HINT_NOICON" );
	if( isdefined (self.script_flag)  && !IsDefined( level.flag[self.script_flag] ) )
	{
		flag_init( self.script_flag ); 
	}
	if(isDefined(self.script_noteworthy) && self.script_noteworthy == "electric_door")
	{
		self set_door_unusable()
		flag_wait( "electricity_on" );
	}
	self set_hint_string( self, "default_buy_debris_" + cost );
	self thread debris_think(); 
}

Of course this would require you made a kvp script_noteworthy = "electric_door" on the trigger

I sense another incoming tutorial