All You Need To Know On How To Wire Garden Lights In Series

You know how to install outdoor lighting. But do you know how to wire garden lights in series? There are many brilliant ideas to upgrade your patio and your front garden driveway. You can get garden arches or even build a garden bar. But none of them will look complete unless you wire garden lighting.

A marble tiled backyard with ground lamps wired in series

You may think that landscape lighting is a job that an electrician could deal with. But we are here to refute that claim and help you DIY. Outdoor lighting installation isn’t as hard as you might think it is. And we can promise that it will make a great impact on your garden and the overall look of your house. 

What is a series circuit?

Before we dive into wiring lights in series, we better understand what a series circuit is. In this type of circuit, the current has only a single path. The electric current goes through every component of the circuit. In simple terms, all the components in a series circuit carry the same current.

Breaking (or opening) a point in the series circuit will lead to stop operating the whole thing. Take, for example, the Christmas tree lights. If a light bulb burns out, none of the bulbs will light until the burnt one is replaced.

Safety comes first

Before walking through the process of wiring outdoor lighting, there are some things you should know to be sure that you are legal and safe:

  1. You need to ensure that you are staying within the building regulations
  2. Any material you’re going to use, such as cable, wire or light, should be suitable for use in an outdoor space and must be protected by an RCD (residual current device) or RCCB (Residential current circuit breaker), which will cut off the power instantly if an accident happens. 
  3. You are obliged by Part P of the building regulations to notify the Building Control Authorities of any electrical activity you’re planning to do outside, or else you should let a Part P qualified electrician do it. 
  4. Let’s say you intend to put cables underground in the outer space of the building. Its regulations state that you have to use SWA or Steel Wired Armoured cable which is  covered with a warning PVC tape to alert anyone digging in the area.
  5. The installation of mains powered outdoor lighting requires it to be powered from a spur of a ring circuit using a 5 Amp fused connection unit.
  6. You should supply your outdoor lights through a 1.5mm² two-core cable, enclosed into a weatherproof box mounted to the wall of the house.
  7. You can put the cable in a conduit or duct. Whatever you choose to use, you should bury them at a depth where nothing can damage them.
  8. If you choose to use a conduit, use flexible plastic electrical one or plastic drain pipes. 
  9. Turn off all power before starting the light installation. You better get a socket or voltage tester for a lighting circuit to remain safe. 

How to wire garden lights in series

Now that you know what to check before starting your light fitting, it’s time to dive into the main electrical work

Hung garden lights wired in series as night decor

We are about to show you how to connect low-voltage garden lights in series and connect them all to the mains power supply. The standard mains wiring is installed to supply electricity at 230V-240V, which isn’t safe to touch. By the way, all the house appliances use 230V-240V; however, they are all insulated and fused for electrical safety. Hopefully, the outdoor lighting system, ground lights, wall lights, halogen, floodlights or led lights are 12-volt low voltage lighting.

Here’s what you need to DIY:

    1. Get a watt transformer and plug it into a weatherproof socket.
    2. Get a 12V cable with separate power sockets. Choose the right size cable depending on the circuit length and the number of lights you want to install.
    3. Attach the cable first to the transformer and then line it up. Drill an appropriately sized hole in the wall (or door, window frame, or decking), line with a conduit, and pass the cable through.
    4. Cover the hole with a silicone sealant to protect it from moisture.
    5. Lay the cable either on or just below the surface and plug in your lights.

Note: Many low voltage fittings come with Plug and Play cabling, 3 way/5 way connector/splitters, extension cables and transformer, giving the option to extend the cable and fit lights to a bigger area.

Advantages and disadvantages of the series lighting circuit

But why should or shouldn’t someone choose to wire garden lighting in series? Let’s see some pros and cons, and then you can decide for yourself.

A porch with a string of garden lights wired in series


  1. It carries the same electric current throughout the circuit.
  2. It’s easy to understand its design.
  3. It doesn’t overheat quickly.


  1. If a wire breaks or a lamp burns out, the whole string will stop working until the false bulb is replaced.
  2. If you add extra light bulbs in a series lighting circuit, it will affect the performance of all the light bulbs.
  3. Adding more loads in a series circuit will increase the overvoltage drop, affecting the electrical appliances.
  4. If you want to add more loads to the circuit, then it’s required to have a high supply voltage.

Series vs parallel wiring 

There are two main circuit types; parallel and series. Below we have a table of the main differences between series and parallel circuits:

Series circuitParallel circuit
Series is a circuit when the current is the same throughout all the elements in the circuit.The parallel one is the circuit when the current has two or more paths to flow.
If a fault occurs, the whole circuit stops operating.If a fault occurs, the circuit doesn’t stop operating, and the current keeps flowing through the other elements. 
All the elements are arranged in a line.All elements are arranged parallel to each other.
If you add more than one resistor to the circuit, the voltage across each resistor will decrease, whilst the current will remain the same.Connected resistors in parallel have the same voltage.

A graphic of series and parallel circuits

Garden lights can boost the overall look of both your garden and house. They can illuminate your yard or highlight a spot. The installation might be a bit tricky. However, you can DIY it as long as you follow our guide.

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