Voltage testing on live lines...

Discussion in 'Landscape Lighting' started by GreenLight, Feb 20, 2009.

  1. GreenLight

    GreenLight LawnSite Senior Member
    Messages: 526

    I was wondering what everyone's techique is for testing voltage at each fixture on a lateral run.

    Example- Home run wire, teed off going to 6 fixtures...
    For a while I was using the technique of removing the lamp on the fixture I was testing while leaving all other lamps on.....Obviously this reading would not be perfect as it is not accounting for the removed lamp and overall I was never thrilled with doing it that way...

    Over the past 6 months I have been elevating the lamp while it remains in the socket and then testing from the socket while the lamp remains on. I know this way im getting a voltage reading that reflects all lamps being on and in use, but it's not the most user friendly method on certain fixtures.

    Anyway, im just trying to get some insight from those in the know on the subject...I know a lot of people test where the lead of the fixture meets the lateral line, but I have always been skeptical about using this method because of varying lengths in leads and such. Any suggestions or criticisms are welcome.
  2. The Lighting Geek

    The Lighting Geek LawnSite Senior Member
    Messages: 886

    The simplest way to combat that is to use the hub method with equal lengths of wire to your fixtures from the connection at the home run. If you use 25' on your fixtures you will experience approximately 1/2 volt drop to the fixture. I have installed literally thousands of fixtures this way and never had an issue and it is easy to duplicate with your employees. Unique Lighting came up with the method and has been promoting it for years.
  3. Lite4

    Lite4 LawnSite Gold Member
    Messages: 3,187

    Ditto what Tommy said, you can also buy a testing device from cast lighting for testing directly at the fixtures too.
  4. GreenLight

    GreenLight LawnSite Senior Member
    Messages: 526

    I am in complete agreement with you and trust me I still intend to do just that. I actually tried to make the hub method a selling point on this job I am doing now, unfortunately I caught some static from the landscape design group I am subbed by for this job. Basically they told me they were familiar with what I was presenting but to use their words "we don't want that spider splice bullsh*t with wires running in every direction in our planting beds" (their words, not mine, and yes they are hot and heavy about trying to get me to chain everything off of laterals).

    I am all about using the unique hubs, trust me, I have just been dealing with the same designer for the past 3 months and he basically forces my hand on certain issues, hub method being one.
  5. INTEGRA Bespoke Lighting

    INTEGRA Bespoke Lighting LawnSite Platinum Member
    Messages: 4,102

    I understand the "hub method", and understand it's advantages and limitations. Keep in mind, that on large, relatively sparsely lit properties it is not going to be all that effective. It will work fine for most typical urban / suburban lots, but not necessarily when you get into large, estate size properties. You need to educate yourself on all forms of wiring techniques and understand the advantages and limitations of each. That way you will be able to design and install the optimal system for the application. Ultimately the lot size, format, location of physical obstacles, features, and system layout will predict what wiring system is best for the job. Doing it right, each and every time keeps you on your toes!

    Have a great day.
  6. Lite4

    Lite4 LawnSite Gold Member
    Messages: 3,187

    I agree with James. The hub is a great method of wiring and the one I use 90% of the time. But sometimes you run into situations where it just isn't feasable or necessary. If they have their panties in a bind about a hub and want everything chained, go to an LED offering for the lighting. It will give you much more flexibility in wiring. Hey James, check your PM.

    MAGLIGHTING LawnSite Member
    Messages: 248

    Check the voltage at the connection at the first fixture on that homerun.
    When you are using brass lugs it's easy. If you are using the hub method. Check the voltage at the hub

    MAGLIGHTING LawnSite Member
    Messages: 248

    HUb set up is Great for beginners and not knocking it but I use it very very very seldom and never with 16 gauge cable in the ground. JS is right you need to know all forms of cabling methods.
  9. steveparrott

    steveparrott LawnSite Bronze Member
    Messages: 1,276

    Here are the CAST tools for measuring voltage at the fixture with the lamp powered up (CTESTMR16, CTESTS8): (Note: I know I shouldn't promote our products here, but no one else makes these items.)


  10. steveparrott

    steveparrott LawnSite Bronze Member
    Messages: 1,276

    When measuring voltage at the hub, keep in mind the voltage loss between the hub and the lamp. This voltage loss varies according to the lamp wattage, lead length and wire gauge.

    After taking the reading at the Spider Splice subtract the following to estimate voltage at the lamp.

    Fixtures with 25' #16/2 lead wire:

    20W: 0.3v | 35W: 0.6v | 50W: 0.8v ​

    Fixtures with 25' #18/2 lead wire:

    10W: 0.3v | 20W: 0.5v ​

    Fixtures with 35' #16/2 lead wire:

    10W: 0.2v | 20W: 0.5v | 25W: 0.6v| 35W: 10.8v | 50W: 1.2v​
    Last edited: Feb 21, 2009

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