Electricians are NOT smarter than landscapers - Contractor Talk - Professional Construction and Remodeling Forum

Rock Headed · 03-22-2008, 04:59 PM

Every single time (admittedly only three occasions) that I have witness a low-volt installation that was performed by a proffessional electrician, they went and wired the bloddy thing up incorrectly. Daisy-chain style. Ac and Dc are different This is reminds me of the old snausages commercial "dogs don't know its not Ac".

Sorry for the BS rant, but I just lost a bid and the electrician did it wrong--now there sits a shoddy lighting job, messing up my beautifully installed landscape! Also the other guy (a fairly sizable company actually) used this ****ty black plastic lights, not the dope-assed copper fixtures that I would have gone with. And I doubt money was the reason. I might have underbid the other guy, who knows? Who cares? Asshole electrician ****ed up my landscaped and I am pissed. End rant.

Have fun 'scaping y'all. And don't let nonsense mess up your fun

walkerj · 03-22-2008, 05:03 PM

It's highly unlikely the lights were DC

NightScenes · 03-22-2008, 05:51 PM

Hey Rock, you can always go back to that client and offer them your services to replace that stuff. You can then charge em double and make even more money.

Sportbilly · 03-22-2008, 05:58 PM

Quote:

Originally Posted by Rock Headed

they went and wired the bloddy thing up incorrectly. Daisy-chain style. Ac and Dc are different

At each fixture you tap the hot and ground, which continue uninterrupted to the next fixture?

Essentially running your fixtures in parallel, thus they each see identically whatever voltage you're using?

Sorry, I've never done landscape stuff, and won't be anytime soon, but it never hurts to learn

Rock Headed · 03-22-2008, 06:41 PM

Walker J--it is a gauranteed fact that the lights are Dc.....

Quote:

thus they each see identically whatever voltage you're using?

My point exactly...this is not how DC works.

Nightscape, thanks for the suggestion, but the customer will likely not know the difference and will just have to keep calling the electrician back to change bulbs...then again, since he daisey chained up like 9 fixtures in a row, the differences in voltage will certainly be visible.

Anyway I'd feel like a jerk informing the customer that their lighting was done wrong. I do not bad mouth the competition.

BTW this thread is not intended as incindiary, I mean noone any offence, just needed to bitch for a minute

Sportbilly · 03-22-2008, 08:24 PM

So they're connected in series, thus each seeing identical, divided voltage. And this means that line loss is shared between the lamps, instead of being obviously different between the first fixture and the last?

This means you can only use so many fixtures before they drop below the optimum voltage, and that if one goes out, they all do?

We are educable you know

JamesNLA · 03-22-2008, 08:58 PM

I think I see why he lost the job. ...and they are called lamps...bulbs get planted in the ground.

Alwaysconfusd11 · 03-23-2008, 07:18 AM

Quote:

So they're connected in series, thus each seeing identical, divided voltage. And this means that line loss is shared between the lamps, instead of being obviously different between the first fixture and the last?

Line Loss?
Resistance of wire over such a short run would be so small.

OHMS LAW! V=IR solves all of your problems and looks like this using random numbers...

They sound to be connected in parallel...

But if series...

woodchuck2 · 03-23-2008, 08:36 AM

If the lights were hooked up in series then the Installer needs to be educated, not everybody. You would have a drop in voltage regardless if AC or DC when wired in series.

orson · 03-23-2008, 08:46 AM

Your circuit is not DC unless you are using a converter or rectifier to change the AC supply to DC, or you are running the landscape lighting from batteries. If the lighting is low voltage it is running on a transformer which uses magnetism to covert a voltage to a lower voltage. Transformers do not change AC to DC. Whether or not a circuit is AC or DC has no bearing on voltage drop due to fixtures in a series circuit, nor any bearing on amperage drop due to fixtures in a parallel circuit.

Rock Headed · 03-23-2008, 09:00 AM

You run one wire straight from the transformer, to a junction point(this main lead is commonly called a "home run"), at which the wire is spliced into individual wires (this junction point is called the "hub"), each going to the individual light fixtures. If run in series or in parallel each lamp will see successively less voltage. Both too much voltage as well as not enough voltage can lead to lamps (or bulbs, if you will) failing.

I could draw a diagram, but it is simple really and most manufacturers of landscape lighting systems have the information regarding proper installation readily available.

NightScenes · 03-23-2008, 09:45 AM

Quote:

Originally Posted by orson

Your circuit is not DC unless you are using a converter or rectifier to change the AC supply to DC, or you are running the landscape lighting from batteries. If the lighting is low voltage it is running on a transformer which uses magnetism to covert a voltage to a lower voltage. Transformers do not change AC to DC. Whether or not a circuit is AC or DC has no bearing on voltage drop due to fixtures in a series circuit, nor any bearing on amperage drop due to fixtures in a parallel circuit.

There ya go. The transformers used are either Toroidal or EI (Core/coil) type though.

It would be foolish to install landscape lighting or just about any kind of lighting in series as this would take out entire sections of lighting if any one lamp burns out.

Sportbilly · 03-23-2008, 11:05 AM

Quote:

Originally Posted by Alwaysconfusd11

Line Loss?
Resistance of wire over such a short run would be so small.

OHMS LAW! V=IR solves all of your problems and looks like this using random numbers...

They sound to be connected in parallel...

But if series...

I've seen some long runs. If you're dealng with low voltage, line loss isn't insiginificant

And I imagine it would be a PITA if one lamp
went out and they all went out

Rockhead, if you simplified your correct circuit, which would it look like? Parallel or series?

Sportbilly · 03-23-2008, 11:11 AM

Quote:

Originally Posted by Rock Headed

If run in series or in parallel each lamp will see successively less voltage.

So you you use a third different way? lol

Rock Headed · 03-23-2008, 12:03 PM

I've already described my wiring configuration, which is industry standard. Maybe I'll draw you a little picture another time. Thanks for the "lol", cute.

I myself am no electrician, I simply know incorrectly laid landscape wiring when I see it. Guess you actually ARE smarter than me. Happy easter, peace.

NightScenes · 03-23-2008, 12:22 PM

When running the wiring in parallel you will have a drop in voltage between fixtures. This is why most are going to the "hub" method of wiring to evenly distribute the voltage to each fixture. This however is also flawed to some degree by the wattage of the lamps that are used on the circuit. A 20 watt lamp will have less voltage drop on it's 25' lead wire than a 35 watt lamp. The "T" method or "loop" are also very good at distributing the voltage evenly although not quite as good as the "hub". The daisy chain, which is what I believe Rock Headed is talking about is the worst method, in that the voltage drop continues down the parallel circuit making each lamp a little dimmer.

Sportbilly · 03-23-2008, 01:09 PM

Quote:

Originally Posted by nightscapespaul

This is why most are going to the "hub" method of wiring to evenly distribute the voltage to each fixture. This however is also flawed to some degree by the wattage of the lamps that are used on the circuit. A 20 watt lamp will have less voltage drop on it's 25' lead wire than a 35 watt lamp.

In other words both conductors are taken to a central point, and tapped off from there to the fixture locations, so that all the fixtures are run in parallel, but with *almost* even conductor lengths, minimising v drop differentials?

Thanks, that's what I wanted to know

Rock, you almost put it this clearly, but not in enough detail for me to visualise it in my head

Learning all the time

orson · 03-23-2008, 08:30 PM

I'm not 100% sure on all of this so maybe someone can second this or point out if I am wrong but here goes...

Parallel circuits have an amperage drop at each fixture but voltage is constant*

Series circuits have a voltage drop at each fixture but amperage is constant

*there is a voltage drop at any point in the circuit due to the distance from the transformer(or breaker as the case may be)

How to calculate voltage drop

Cable length - length of cable used from the transformer to the fixture on which you are measuring the voltage drop (in feet).
Total watts - sum the wattages of every lamp along the cable length.
Cable constant - indicates the thickness of copper wire; a thicker wire results in less voltage drop.

Cable length X Total watts

= Voltage DropCable constant

Configuring the circuit as a "T" is done to cut the Cable Length down since you can calculate the drop individually on each side of the "T"(These are also sometimes referred to as "I" layouts)

Configuring a loop system can also cut down on voltage drop, please note this is still a parallel 12V AC system. Both ends of the positive are hooked to the same positive terminal on the transformer and both ends of the negative loop are hooked to the same negative terminal on the transformer.

How voltage drops affect a lamp:

Voltage Light Output Lamp Life
12.5 V 170% 80%
12 V 100% 100%
11.5 V 80% 200%
11 V 75% 300%
10.8 V 70% 400%
10.5 V 65% 500%

As you can see, a lamp with a design voltage of 12 Volts will deliver 80% of its light output and its life will double by reducing the voltage to 11.5 Volts. The light loss is hardly noticeable to the naked eye while lamp life is generously extended. Therefore, you want to experience a slight voltage drop to all lamps in your low voltage lighting system. The recommended feed to each lamp is between 10.8 Volts and 11.5 Volts.

klkanders · 03-23-2008, 08:49 PM

Hey Guys,
I am glad to see Paul got involved with this thread. He is a good guy who really tries to explain things clearly so everyone can understand. What I find amazing is he didnt get offended by the topic but offered up his knowledge to help clarify things anyway. He is an electrician also.

Keith

JoeinJasper · 03-24-2008, 07:26 PM

In the above example, Would there be a performance vs. price advantage if the 12ga loop was replaced with a 10ga T or hub lay out? Thanks, Joe