Meanwell 12v power supply with led strip

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Hello,

We are building display cabinets for a retail store in Los Angeles and had a few questions on LED strip lighting. Each cabinet would contain the following items:

Meanwell HRPG-450-12 power supply 37.5a @ 12v
http://www.trcelectronics.com/View/Mean-Well/HRPG-450-12.shtml

24pcs x 5m LED 3528 strip light

My questions are the following:

1. The power supply would be mounted on the top of the cabinet which is 8 feet from the ground. Are we required to use a NEMA 1 type enclosure for it at this height? I read that if over 7 feet, it is not required. Can the terminals of the power supply be openly accessible at this height? An example of the NEMA enclosure is here https://www.trcelectronics.com/View/TRC/TRC-E-HRP300450600.shtml

2. Do the LED strip lights need to be listed? What documentation may the inspector expect?

3. We plan on running 4 cabinets per circuit at 220v (9.6 amps total). We would like to wire the cabinets with a NEMA 6-15p plug coming off the top of them, going to the ceiling. How would we direct the on-site installing electrician to prep the ceiling? Can they hang an SOOW type cord from a junction box on the ceiling above the display case with a 6-15R type plug? So basically, the SOOW cord hangs off the ceiling to the outlet, around 8 feet off the ground. And the case plugs in to the outlet.

4. With above spec'd, should there be a strain relief or something for the cord? I'm guessing the ceilings are at 12-20 feet tall.

5. Will the electrical inspector wait to see the entire display cases installed and plugged in or would they check off a final with just the outlets in place?

Thanks in advance for any advice! :D
 
Here is some permit info from LA county. It specifically states a permit is not required for

"Low-energy power, control, and signal circuits that are not an integral part of an appliance and in which the power is limited from a source having a rated output of not more than 30 volts and 1,000 volt-amperes."

electrical low voltage code.jpg
http://dpw.lacounty.gov/bsd/permitinfo/

Not sure if this applies to this situation?
 

James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
How many leads are you planning to take off from your transformer? This looks to be 450 watts? 37.5 amps? 9.5 amps per cabinet?

How far is each cabinet from the transformer?

I'm going to go out on a limb and say you might need to look at voltage drop issues before you commit to your wiring scheme.

For instance, if you run separately to each cabinet, say 16 feet, you would need 10 gauge to stay under 5% voltage drop.

If you were to daisy-chain your cabinets, you would need 6 gauge to stay under 5% drop

The worst thing would be if the end of your strip is really dim, or not lit at all, because voltage too low

If it were me, I would use 1 transformer per cabinet, and go with 24 volt ribbon and transformer.

I'm going to be adding rgb ribbon in a church with about the same wattage, and 24 volt was a definite - with multiple transformers

Some drivers:

http://smile.amazon.com/gp/product/B00KTJE3L4?psc=1&redirect=true&ref_=oh_aui_detailpage_o09_s00

http://smile.amazon.com/Meanwell-En...id=1452259401&sr=8-15&keywords=24v+led+driver

http://smile.amazon.com/Power-Suppl...id=1452259401&sr=8-12&keywords=24v+led+driver

Some ribbon:

http://smile.amazon.com/HERO-LED-32...id=1452259243&sr=8-16&keywords=24v+led+ribbon

http://smile.amazon.com/HERO-LED-12...qid=1452259243&sr=8-7&keywords=24v+led+ribbon
 
How many leads are you planning to take off from your transformer? This looks to be 450 watts? 37.5 amps? 9.5 amps per cabinet?

How far is each cabinet from the transformer?

I'm going to go out on a limb and say you might need to look at voltage drop issues before you commit to your wiring scheme.

For instance, if you run separately to each cabinet, say 16 feet, you would need 10 gauge to stay under 5% voltage drop.

If you were to daisy-chain your cabinets, you would need 6 gauge to stay under 5% drop

The worst thing would be if the end of your strip is really dim, or not lit at all, because voltage too low

If it were me, I would use 1 transformer per cabinet, and go with 24 volt ribbon and transformer.

I'm going to be adding rgb ribbon in a church with about the same wattage, and 24 volt was a definite - with multiple transformers

Some drivers:

http://smile.amazon.com/gp/product/B00KTJE3L4?psc=1&redirect=true&ref_=oh_aui_detailpage_o09_s00

http://smile.amazon.com/Meanwell-En...id=1452259401&sr=8-15&keywords=24v+led+driver

http://smile.amazon.com/Power-Suppl...id=1452259401&sr=8-12&keywords=24v+led+driver

Some ribbon:

http://smile.amazon.com/HERO-LED-32...id=1452259243&sr=8-16&keywords=24v+led+ribbon

http://smile.amazon.com/HERO-LED-12...qid=1452259243&sr=8-7&keywords=24v+led+ribbon

Hello James, thanks for the reply. Here is a diagram of what is going on. 220v x 15 amp supply circuit. Goes to 4x meanwell power supplies (2.4 amp input draw per supply). Each Meanwell supply has 37.5 amps output going to 24 x led strip which draw 1.5 amp each @ 12v.

View attachment 14100
 

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  • WIRING DIAGRAM FOR CENTER CASES.jpg
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James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
13.5 amps (9 rolls) is gonna be too much on a 16 ga wire at a length of 10 feet.

That's enough to make the ends of your rolls substantially dimmer than the beginning.

It's hard for guys to fathom, but the lower your starting voltage, the more drastically it drops.

13.5 amps, 16 ga wire, 10' length = 9.02% voltage drop.
It works out almost exactly to 1% drop for each roll you add on that 16ga wire.

When I install full rolls, I run a separate 18ga home run, up to 25 feet, from the transformer to each ribbon

With 16ga wire at 10', I would put max 3 rolls per run
 
13.5 amps (9 rolls) is gonna be too much on a 16 ga wire at a length of 10 feet.

That's enough to make the ends of your rolls substantially dimmer than the beginning.

It's hard for guys to fathom, but the lower your starting voltage, the more drastically it drops.

13.5 amps, 16 ga wire, 10' length = 9.02% voltage drop.
It works out almost exactly to 1% drop for each roll you add on that 16ga wire.

When I install full rolls, I run a separate 18ga home run, up to 25 feet, from the transformer to each ribbon

With 16ga wire at 10', I would put max 3 rolls per run

Good idea, will definitely run more wires. In the past on similar installs, I've only run 2 strips per 16ga. The wire is cheap and the distance is short. I was thinking more of max capacity than voltage drop. Thanks for the advice James!

Any ideas on if we need an enclosure for the power supply? Or on dropping the power down from the ceiling?
 

James L

Senior Member
Location
Kansas Cty, Mo, USA
Occupation
Electrician
No problem, quickersol.

I like the power supply enclosure even if it may not be required. I didn't look closely, but does your power supply have a flip lid over the treminals? I'm not crazy about leaving exposed terminal anywhere there's a potential for someone to get into them. And the price looks cheap enough in the larger scope of cost.

I also wonder if that enclosure is made for that power supply? There's a fan built into the power supply to help it run cooler, but are the vents in the enclosure located to provide maximum air flow through the driver?

And I would defer to someone more knowledgeable about the use of SO cord. I can count on one hand the number of times I've used it, always with strain relief connectors, but have never used it on other than movable equipment.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
And I would defer to someone more knowledgeable about the use of SO cord. I can count on one hand the number of times I've used it, always with strain relief connectors, but have never used it on other than movable equipment.

If it were me with a drop of 12-20 feet down to the tops of the cabinets I would opt for conduit drops and receptacles mounted on the tops near the power supplies. If there are multiple cabinets next to each other one drop could run along the tops with receptacles at each of the power supply locations.

If you want to use SO cord, two methods-
1) Box in ceiling and a plate with a hole for a strain relief, SO drop down to the cabinet with a connector body on the end.

2) If you want a receptacle in the ceiling- twist lock receptacle and plug, snubber type strain relief attached separately to the ceiling to support the SO drop and connector body at the other end.


-Hal
 

iwire

Moderator
Staff member
Location
Massachusetts
If it were me with a drop of 12-20 feet down to the tops of the cabinets I would opt for conduit drops and receptacles mounted on the tops near the power supplies. If there are multiple cabinets next to each other one drop could run along the tops with receptacles at each of the power supply locations.

You don't work on store fixtures much do you? :)

Conduit would be unheard of in a pre-manufactured cabinet, sometimes miles of 1/2" FMC.
 
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