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View Full Version : New Daisy-Chain Calculator for LED's!


steveparrott
02-18-2011, 08:07 PM
Fellow Lighting Geeks,

The new LED revolution finds LL installers reverting back to the daisy chain method of wiring. Since wattages are much lower, it does make sense (in some installations) to tap off along a single wire run instead of using multiple home runs to Spider Splice locations.

I was curious about this so I made some calculations and was surprised to find that voltage loss is still an important consideration. This is especially evident when the higher-wattage LED fixtures are used, and when you need to combine incandescent fixtures and LED fixtures.

In some situations, you need to move up to the 13, 14, or 15V taps. In other situations, the voltage loss between the first and last fixture exceeds the voltage range of the particluar LED.

With this in mind, I created an Excel calculator that predicts voltage loss. (Eventually, I'll convert it into a web page.)

I strongly encourage anyone who likes playing with calculators, to download this calculator (beta version), put it to the test, and post feedback in this thread.

All who provide relevent feedback get a free CAST Lighting hat!:)

Download the new CAST System Calculator - Daisy Chain Version (http://www.cast-lighting.com/learning/articles/4_article_cast-voltage-calculator-daisy-chain).

Thanks!

RLI Electric
02-18-2011, 09:01 PM
Steve
Make it into an app. A free one please:)

NightScenes
02-21-2011, 05:24 PM
For BB too, please! LOL

Thanks Steve!!!

steveparrott
02-21-2011, 05:27 PM
Paul and Bob, did you try out the calculator? I'm really looking for feedback.

I also have a meeting tomorrow with my developer about the aps.

Thanks,

NightScenes
02-21-2011, 05:29 PM
Just now downloaded it so give me a few days Steve. I'll try it out.

JG Supplies
03-03-2012, 08:47 PM
[QUOTE=steveparrott;3905680]Paul and Bob, did you try out the calculator? I'm really looking for feedback.

I also have a meeting tomorrow with my developer about the aps.

Thanks,

Steve, I downloaded the spreadsheet and tested it using OpenOffice. The summing of the V/A per junction worked with Feet and Fixture V/A entries but the Total Wire and Fixture V/A's resulted in an error. #DIV/0. The Tap and Wire pull downs were used to select those values and not typed in. The Fixture V/A calculator worked OK. Hope this helps. Len

steveparrott
03-04-2012, 01:49 PM
[QUOTE=steveparrott;3905680]Paul and Bob, did you try out the calculator? I'm really looking for feedback.

I also have a meeting tomorrow with my developer about the aps.

Thanks,

Steve, I downloaded the spreadsheet and tested it using OpenOffice. The summing of the V/A per junction worked with Feet and Fixture V/A entries but the Total Wire and Fixture V/A's resulted in an error. #DIV/0. The Tap and Wire pull downs were used to select those values and not typed in. The Fixture V/A calculator worked OK. Hope this helps. Len

I'm working on a new version of the calculator and will upload it today - still in beta version.

Fireguy97
03-04-2012, 03:52 PM
I'm working on a new version of the calculator and will upload it today - still in beta version.

Am I missing something? I didn't get an xls file in the compressed file.

Tried to open with Excel 2003

Mick

steveparrott
03-04-2012, 04:29 PM
Am I missing something? I didn't get an xls file in the compressed file.

Tried to open with Excel 2003

Mick

This is a strange quirk with Internet Explorer - it interprets an .xlsx file as a .zip file. It opens fine in Firefox or on a Mac.

Ed Lethert (The Low Voltage Guy (http://www.mnpowerlimited.com/who_is.htm)) has taken on the development of this calculator as a work of passion. We've been going back and forth for months with various drafts and Ed has spent countless hours refining the calculations.

Unlike a calculator for incandescent lighting, LED's with their complex drivers inject variables that are not easily calculated. You'll see in the current version several refinements over the previous draft. These include the ability to use the calculator for the T-Method, temperature compensation, a +20% column for adjusting for errors that come in with very large systems, energy cost calculations, alerts when voltage ranges are exceeded.

By the way, to calculate a T-Method installation, use junction 1 to indicate where the homerun connects with the middle fixture. At that junction, put all the fixtures from the shorter leg of the T, then continue to enter each fixture junction on the second leg of the T.

For example if the set-up looks like this:

F1 F2 F3 F4 F5(T-Junction) F6 F7 F8 F9

Enter the first 5 fixtures at the first junction; then J2 is fixture 6, J3 is fixture 7, and so on.

irrig8r
03-04-2012, 06:15 PM
Opens in Chrome.

Westmount
04-22-2012, 08:06 PM
:clapping:
This calculator is off the hook! Thank you! I was wondering if the calculator makes the assumption that there is a daisy chain set-up at the first junction? If you have a scenario with a long run and a t-junction that just serves as a junction with no additional load applied at the junction itself and then continues on in 2 directions to spider at the end of each...is the loss distributed equally on both wires to the end spider box junctions and therefore no need to calculate any differently than if it was one long run to one spider box with the total load of the entire circuit applied at the end? (as if there was no T in the line at all?). I am guessing that the calculator always assumes 25 ft lead wire from spider junction to fixture at 16ga?

On My voltage range section, the line 9 (A) fixture LOW and High range shows as blue box, but lines 10-14 shows as yellow highlighted box, even though the same values are entered in 9 and others. Is the software trying to draw my attention to an unacceptable range or is this just colored background for these particular cells?

Once again...really impressive...thank you for putting it out there. would love to see it converted to android app for field use!

steveparrott
04-22-2012, 08:51 PM
:clapping:
This calculator is off the hook! Thank you! I was wondering if the calculator makes the assumption that there is a daisy chain set-up at the first junction? If you have a scenario with a long run and a t-junction that just serves as a junction with no additional load applied at the junction itself and then continues on in 2 directions to spider at the end of each...is the loss distributed equally on both wires to the end spider box junctions and therefore no need to calculate any differently than if it was one long run to one spider box with the total load of the entire circuit applied at the end? (as if there was no T in the line at all?). I am guessing that the calculator always assumes 25 ft lead wire from spider junction to fixture at 16ga?

On My voltage range section, the line 9 (A) fixture LOW and High range shows as blue box, but lines 10-14 shows as yellow highlighted box, even though the same values are entered in 9 and others. Is the software trying to draw my attention to an unacceptable range or is this just colored background for these particular cells?

Once again...really impressive...thank you for putting it out there. would love to see it converted to android app for field use!

In your scenario with the T-Junction remote from the fixtures, you would use the instructions I give in my previous post. Take all the fixtures from the leg with the lightest load and enter them in the Junction 1 row, then used the subsequent junctions to enter the fixtures from the second leg.

As for cell colors. Blue indicates cells where you can enter and edit data; Yellow indicates non-editable cells; Cells that turn white indicate when calculated values exceed voltage range (either above or below).