How do you work out the cable cross-section for a LED pool strip?

Choosing an LED strip for your swimming pool isn’t just a matter of working out how many metres you need.

You should also be aware that:

• if it works at 12 V or 24 V;
• how much it consumes per metre;
• how many metres you are going to install;
• how far away the fountain will be;
• whether you will be using one or more strips;
• and what cable cross-section is required for each route.

If it is not calculated correctly, the following may occur voltage drop and the strip may not be under the expected tension.

To avoid having to do all these calculations by hand, we have created a calculator specifically for LED strip installations.

1. Before calculating the cable length: choose the right LED strip

The first thing is to know exactly which product you are going to install. Do not calculate the cable length using approximate figures. Always check the technical data sheet:

• Voltage
  12 V or 24 V.
• Type of current
  For example, 12 V DC.
• Power
  Usually expressed in W/m.
• Length
  Metres of strip that you are going to use.
• Type of lighting
  White or RGB.
• Number of drivers
  For example, 2-wire or 4-wire RGB.

For swimming pool installations, you should also check that the strip is designed for that application. The TRYLED Flexible Neon LED Strip, IP68 It is currently available in 12 V and 24 V DC, and in cool white, warm white and 4-wire RGB. You can also view the full range of Trypool swimming pool lighting.

How to use the LED strip cable calculator

You don’t need to do the calculations by hand. The tool is designed so that you can enter the actual details of the installation and compare different options.

Step 1. Select the voltage

Please indicate whether the strip operates at:

12 V

or:

24 V

Always use the voltage specified in the product data sheet.

Step 2. Enter the W/m

Step 3. Enter the number of metres of tape

It indicates only the length of each strip.

Example: 3.5 m

You can then specify how many identical strips you are going to install.

Step 4. Enter the number of strips

For example:

1 strip/ 2 strips/ 3 strips

This figure is important because it increases the total power output of the system.

Step 5. Enter the distance from the source

Measure from the power supply to the strip. If there is:

20 metres

Enter: 20 m

Do not enter 40 m. The calculator already takes the required electrical distance into account internally.

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Step 6. Choose the type of strip

Select:

White — 2-ply o RGB — 4-wire

The tool adjusts the calculation to the selected settings.

Step 7. Explain how you are going to wire several strips

If you’re going to install several, you can choose from:

Standard cable o Separate cable per strip

This information may significantly affect the required section.

Step 8. Insert the cable that is soldered to the strip

If the strip includes, for example:

20 cm of 0.34 mm² cable

Enter these values as well.

Although it is a short stretch, it forms part of the circuit.

Step 9. Choose between single-ended or dual-ended power supply

You can specify:

Feeding from one end o Feeding from both ends

If you select two end points, enter the distance for each route.

Step 10. Enter the section you want to check

For example:

The calculator will check that section and will also display the recommended commercial section based on the data entered.

3. How to interpret the calculator’s result

Once you have entered the data, focus primarily on four values:

The calculator initially uses a criterion based on the maximum drop in the 3 %, which can be amended.

For example, at 12 V:

3 × % at 12 V = 0.36 V

Therefore:

12 − 0.36 = 11.64 V

The calculator serves as a tool to assist in analysing voltage drop. The complete installation must also verify the capacity of the conductors, the power supply, the controller, the protective devices and the applicable electrical requirements.

4. Why does distance have such a big impact?

Because the cable has resistance. The longer the distance, the greater the voltage drop may be if we maintain the same cross-sectional area. Let’s look at a very simple example.

Panel: 10 W/m

Length: 3.5 m

Power: 10 × 3.5 = 35 W

At 12 V: 35 ÷ 12 = 2.92 A

It is not the same to carry that 2.92 A for: 2 metres that during: 20 metres

That is why two installations using exactly the same strip may require different cables.

5. What happens if we install several LED strips?

The powers are added together. For example:

We have two strips of: 35 W each

Total power:

35 + 35 = 70 W

At 12 V:

70 ÷ 12 = 5.83 A

But there is another important point:

Do the strips share a cable or do they have separate circuits?

Standard cable

SOURCE
   ↓
MAIN CABLE
   ├── Strand 1
   └── Strand 2

The main section carries the current from both strips.

Separate lines

SOURCE

├── Cable 1 → Strip 1

└── Cable 2 → Strip 2

Each journey is calculated separately.

The calculator allows you to compare the two configurations.

6. Feeding from one or both ends

A strip can be powered from a single end:

CONTROLLER → [ LED STRIP ]

However, in certain installations, it may be advisable to supply power from both ends:

              → END A
CONTROLLER
 → END B

This can be helpful when we want to minimise voltage differences along a long strip.

The calculator allows you to select the following directly:

Feed from both ends and enter the distance to each side.

7. Very important: both ends must be connected to the same modulator

If you feed a strip in from both ends, We do not recommend using two separate modulators.

Even if you need to lay more cable, both ends must come from the the same modulator or controller.

Correct

Power supply
 ↓
RGB modulator itself
 ├────→ end A
 │
 └────→ end B

Not recommended

Modulator 1 → end A
 [ LED STRIP ]
Modulator 2 → end B

Two independent modulators could send different signals to the same strip.

At Trypool, you can browse the range of swimming pool lighting controllers.

8. How to connect several LED strips

When there are several strips, we recommend planning the installation in parallel.

For example:

Source
   ↓
Modulator
   ├── Strip 1
   ├── Strip 2
   └── Strip 3

And if each strip needs to be powered at both ends:

Source
   ↓
Same modulator
   │
   ├── Strip 1 → end A
   │ → end B
   │
   ├── Strip 2 → end A
   │ → end B
   │
   └── Strip 3 → end A
 → end B

We do not recommend connecting all the strips one after the other as if they were a single, very long strip.

Before you do that, always add up:

total power + total current

and check the capacity of the power supply and the modulator.

9. 12V or 24V?

One of the advantages of the calculator is that you can change the voltage and see what happens.

Let’s take a look at an installation of:

100 W

12 V

100 ÷ 12 = 8.33 A

24 V

100 ÷ 24 = 4.17 A

For the same power, increasing the voltage reduces the current. This can make design easier when dealing with significant distances. But be careful:

12V DC and 24V DC are not interchangeable

The strip, power supply and controller must be compatible with the chosen voltage.

You can look up, for example:

• 150 W power supply – 12 V DC
• 150 W power supply – 24 V DC
• Lighting accessories and controllers

10. 4-wire RGB strips

On a four-wire RGB strip, you will normally find:

common positive + R + G + B

If the strip is powered from both ends, the connections must match.

END A TO END B

+  ─────────────────  +
R  ─────────────────  R
G  ─────────────────  G
B  ─────────────────  B

In other words:

+ → +

R → R

G → G

B → B

Channels must not be crossed, nor must connections be reversed.

You can also check out our content on Wi-Fi control of swimming pool lighting to find out about other ways of controlling the system.

12. Which LED strip should you use in a swimming pool?

Calculating the cable length only makes sense if we first choose a product that is ready for installation.

For this type of project, you can consult the TRYLED Flexible Neon LED Strip, IP68.

The current entry includes versions of 12 V and 24 V DC, cool white, warm white and 4-wire RGB.

To complete a project, you can also have a look at:

• TRYLED Flexible Neon LED Strips
• Lighting controllers
• Lighting accessories
• Swimming pool lighting

13. Checklist before installation

Before feeding through the first cable, check:

• Tension in the strip.
• AC or DC.
• W/m.
• Metres of each strip.
• Number of strips.
• Total power.
• Total current.
• Distance from the source.
• Section of each route.
• Fountain capacity.
• Modulator capacity.
• Shared or separate cable.
• Feeding from one or both ends.
• Connecting the strips in parallel.
• Correct polarity.
• R, G and B values.
• If there is a dual power supply, both ends are connected to the same controller.

Frequently asked questions

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