Posts Tagged ‘how to calculate’

All About Transformers

March 5th, 2010

  TA Series 12v Transformer Painted

Our goal is to provide a simple, cost-effective, and informative format for purchasing low voltage landscape lighting transformers. Be sure to check out our line of L.E.D. transformers and bulbs.

Our transformers are priced at wholesale (available to all) and ready for shipping within 24 hours (except for weekends/holidays). All transformers have a warranty, are easy to install, and have instructions for mounting & wiring. As with any such device, follow all safety instructions.

Torodial Cores Transformers:

  • Run quieter than magnetic core transformers
  • Run cooler
  • More energy efficient: only draws what it uses
  • Longer lasting: best on the market

Benefits:

  • TR Series large terminal allow you to use up to #6 wire for home runs
  • Stainless steel will not rust or corrode
  • Multiple taps allow for longer runs without voltage drop
  • Plugs into a GFCI outlet
  • Timer fits inside the enclosure
  • Easy pluggable photocell ready (side knockouts)
  • Removable door and bottom panels for easy access

 

Voltage Drop

March 5th, 2010

Measure the distance from the transformer to the very first fixture on each run. You do this to calculate the voltage loss. Use this formula:

Cable Voltage Drop = (Wire Run length x Total watts on the run/ Constant) x 2

12/2 wire cable has a constant of 7500

10/2 wire cable has a constant of 11920

8/2 wire cable has a constant of 18960

These guidelines are used for illustration purposes and manufacturer Installation & Instruction Manuals should be used for actual installation.

Calculate the Load

March 5th, 2010

These multiple tap landscape lighting transformers have built in secondary circuit breakers connected to the commons (COM). Each circuit or COM can handle up to 25 Amp or roughly 300 watts each. If a circuit exceeds 25 Amps you will likely overload the circuit and trip the breaker.

To illustrate:

A) 300W transformer has one COM and can handle up to 300 watts

B) 600W transformer has two COMs and each COM can handle 300 Watt (2×300=600)

C) 900W transformer has three COMs and each COM can handle 300W (3×300 = 900)

Now:

  • Add up your fixture’s total wattage and divide into 300 Watts (25amp) maximum per circuit
    • 40 fixtures @ 20 watts each = 800 watts. Requires 2.6 circuits or 900 watt (3 circuit) transformer
    • Select your cable/wire