Addressing Light Fixture Pendant Families

[adam.jw]

Here's my ideas. All of which have draw backs and positives.

Type "A"

1. Create a Workplane Based (so I can check the Always Verticle box in the Family Categories settings) Light Fixture famly.
2. This is the "host" family, light fixtures without the chain hangs will nest into this family.
3. This host family will have the light source disabled, we simply want to use it for containing our nested light fixture.
4. This host family will require a connector, voltage, and load -- as nested connectors cannot be circuited to.
5. The host family will flex the cables up and down, which will move the nested light fixture family with IES value up and down.
6. The nest family will have the light source defined for proper rendering and calculations in ElumTools.
7. The nest family will be set to "Shared" in the Family Categories parameters.

Pros:

• Light Fixtures are able to be swapped out of the Host family rather easily. 
• Since the nested family is shared, this allows easy updating if we want to change something. It also allows it to be picked up for rendering, and it also means the light source IES file is accurately placed in space so ElumTools can calculate it corrently.

Cons:

• Doubling of schedulable elements requiring a filter to elminate the host (and only recognize the nest).
• Confusion of tagging... there's now two families that could be tagged because the nested fixture is just as taggable as the host
• Doubling the analysis of spaces (for watts/sq ft)... the nested shared family must have it's load set to zero, otherwise your space calculations will be erronous (double).
• Since we only want to use the nested family, but in order to keep Revit from doubling our space calcs, having zero set in the Apparent Load parameter will incorrectly display zero in the schedule.
• Since connectors can not be nested, you need a connector on the Host family in order to properly circuit.

Type "B"

1. The Host family is now a Generic Model.
2. The host family will NOT be nesting in the Light Fixture
3. The user will place the host family first, then, place the light fixture without pendant chain hangs to the reference plane inside the host family that moves up and down based on the pendant lenght.

Pros:

• Basically, all of the cons of Type A are now elminted. It will be easier to schedule, and easier to circuit.

Cons:

• More steps, and easier to screw up.
• Model groups will help alliviate this problem. But again, that's an additional step.

So I'm leaning towards going with Type B... unless you folks have any suggestion. Yes it will be a bit more work on the front-end, but it will pay of in terms of calculations and scheduling.

Here's the families:

https://dl.dropbox.com/u/22838635/revit/Type%20A.rfa

https://dl.dropbox.com/u/22838635/revit/Type%20B%20-%20host.rfa

https://dl.dropbox.com/u/22838635/revit/Type%20B%20-%20hostee.rfa

[tkendrick]

If I understand what you're asking, you want to be able to control the length of the pendant hanging down?

This looks really over-complicated. I editted a manufacturer's family to have a Pendant Drop parameter which controlled a dimension to move the entire head up and down, if the light source is Locked to the appropriate surface, you're lighting calculations will always work. I just used model lines, or you could use an extrusion. And I didn't have any nested families, or have to place 2 different ones.

[adam.jw]

But what happens when you're on a sloped ceiling? If your family is Face Based, your fixture will tilt incorrectly.

[tkendrick]

For the example I mentioned, that light was on a sloped ceiling so I had to place a reference plane, I named it, and hosted the light to the reference plane. This particular project, the architectural model had ceiling based fixtures in it, so they cut the ceiling, which made it really hard for me to place my lights, because of the hole in the ceiling, they kept hosting to the floor and they wouldn't stay hosted to the ceiling. So I used reference planes instead.

[CoreyDaun]

My pendant lights come in level while hosted on a sloped ceiling. See below. Otherwise, are you opposed to Reference Planes? The more hoops you jump through, the more likely it is that you'll trip up. Or the people following you will. Believe me, I know...

Under Family Category and Parameters, check the box for 'Always Vertical'. I have defined the pendant lengths to be calculated based off the manually inputted "lowest pendant length" and the inputted "ceiling slope ratio" parameters.