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Power draw / Daisy Chaining

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Debbie Dunkley:
Happy New Year Everyone - I hope your start to 2023 has been a good one!

I have a question:

I always daisy chain power to my truss lights but I just added one more and I'd like to make sure I have this right. Am I restricted only by power draw of all fixtures added together and cord gauge?? They are all very low draw.

I have 8 (multi) fixtures total ( 4 per side) and I feed each side separately so 3 are daisy changed from the first fixture each side.

Fixtures...
1) .64A
2) .4A
3) .18A
4) .33A

Brian Jojade:
When you daisy chain, you also need to know how much current each fixture can support.  While they may have powercons, that doesn't mean they can support 15 amps internally.

Some lights have their fuse on the passthrough. Others just use thin cable with no fuse on the passthrough.

But, at the current draw you have listed, you're at under 2 amps.  Even the worst of the worst should be able to handle that.  A 24 gauge wire is rated at 3 amps, for reference.

Erik Jerde:
Most fixtures with pass through power usually list in their specs the max number of fixtures supported in a chain.  You can use that info to work back what the recommended max current draw through one fixture would be.

Debbie Dunkley:
I can find 3 of the fixtures maximums in their respective manuals. However, the 2 ADJ fixtures indicate they have to be daisy chained to the exact same fixture. All mine are different.
1) ADJ = 13 max - 'must' be same type.
2) Chauvet = 11 max - no restrictions
3) ADJ = 30 max - 'must' be same type
4) Unknown brand. no info.

Erik Jerde:

--- Quote from: Debbie Dunkley on January 16, 2023, 03:34:03 PM ---I can find 3 of the fixtures maximums in their respective manuals. However, the 2 ADJ fixtures indicate they have to be daisy chained to the exact same fixture. All mine are different.
1) ADJ = 13 max - 'must' be same type.
2) Chauvet = 11 max - no restrictions
3) ADJ = 30 max - 'must' be same type
4) Unknown brand. no info.

--- End quote ---

They only give the must be same type thing because that way they're in a better position when someone does something stupid like putting a coffee maker on the end of the chain and starting a fire.  Power is power, the fixture won't care what's plugged into it as long as you don't exceed it's ability to pass through power.

Doing the math you get the following for max load through a given fixture:
1) 7.68A
2) 4A
3) 5.2A

That's by taking the max fixtures in a chain, remove one (because the we're finding the load that is passed through) and then multiply.  For the first this is (13-1)*.64A.

Once you look past the CYA lawyer stuff it's like most power stuff where you just have to do the math.  It's entirely possible that with staggered startup you could run more on a chain but they need to be careful of stuff like inrush current when you power up a whole chain at once.  I'd just go with what you can deduce from the manual.

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