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Great service Quick refund on the wrong part ordered. Correct part reordered and received 2 days latter. Great company to deal with.
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We often have people ask about the correct light bulb size and how to identify a replacement. There are many bulb standards and lighting types, which can become confusing when the old globe has no clear markings.
Caravans and RVs normally use a smaller group of fittings. Once you identify the base, voltage and size, you can choose between fluorescent, incandescent, halogen and LED replacements.
This guide covers the common systems used in caravans and RVs:
| What To Check | Why It Matters |
|---|---|
| Voltage | Many caravan lights are 12V, but some oyster fittings also include a 240V globe. Do not fit a 240V lamp into a 12V holder or the other way around. |
| Base style | Match the physical fitting first: bayonet pins, screw thread, wedge body, festoon caps, or bi-pin spacing. |
| Contacts and pins | Single-contact and double-contact bayonet globes are not interchangeable. Offset bayonet pins also matter. |
| Size and wattage | Measure the old globe and stay close to the original wattage or LED equivalent so the fitting does not overheat or foul the lens. |
If the old markings have rubbed off, remove the globe and compare the base, contacts, pin position and overall size. For 240V fittings, wiring changes or damaged holders, use a licensed electrician. For tail light wiring or unclear 12V polarity, use an auto electrician.
Developed by Thomas Edison, the creator of the electric light bulb, this standard continues to be used throughout the world today.
The most commonly used household version is E27. E stands for Edison, and 27 is the thread diameter in millimetres. While these do exist in some RVs, they are not as common as the other styles.
Above: The Edison Screw is not sold at Caravans Plus.
This system is common in countries of the former British Empire such as Australia. The most common sizes in caravans and RVs are BA9, BA15s, BA15, BAY15 and BA22d. BA stands for Bayonet, the number is the size in millimetres, s means single contact and d means double contact.
12V bayonet fittings with a single contact are identified by one contact plate on the base of the globe, as shown in the BA15s image. This is the positive connection, while the outer metal shell provides the earth. A double-contact globe has two contact plates. One is positive and the other provides earth.
BAY15 bulbs are also double contact. These 12V units are normally found in the tail lights of your caravan, RV or tow vehicle. The double contact points allow for dual function within a single globe. They are commonly used in tail and brake lights and can be identified by two filaments inside the globe. The side pins are offset so the globe can only be inserted one way.
BA22d is normally a 240V globe that fits many light fittings found in Australian residential dwellings. It is also used as the 240V function in many oyster style light fittings found in caravans. While shown here with a filament, this style has often been replaced by fluorescent or LED options for lower running costs.
As with all bayonet fittings, the wattage can usually be found printed on the base of the bulb or on the glass itself.
If a 12V globe in a dual-voltage oyster light looks like a BAY15 but has no readable markings, check the contact plates and the side pins before ordering. A BA15s has one base contact. A BA15d has two level pins and two base contacts. A BAY15d has two base contacts with offset side pins. The offset pins are an important clue because they stop a dual-function globe being fitted the wrong way around.
Above: Bayonet fittings can be incandescent, LED or fluorescent.
Bi-Pin, or Bpin, was first seen in 1893 and was designed for Westinghouse as opposition to the Edison Screw. This standard is commonly used on globes such as halogen lamps and fluorescent tubes. The pins on some lamps, especially halogen, are placed closer together. This helps prevent the wrong type being fitted, which could create excess heat and a fire risk.
With the advent of LED, the Bi-Pin system is still used, although LED heat output is much lower than halogen. The G4 standard is often used with LED replacements so the new lamp can fit into the existing receptacle.
The most commonly used standards in caravans and RVs are G4, G5 and GX5.3, although there are others. The G prefix stands for glass, and the number means the pin centres are that many millimetres apart. For example, G4 pin centres are 4mm apart.
Apart from the many smaller G4 based lamps, MR or Multifaceted Reflector globes are probably the most common interior lighting system you will find in caravans and RVs produced in the last 10 years.
Although there are three types, MR8, MR11 and MR16, the latter two are the most common you will encounter. The numbers represent the diameter. For example, the MR16 is 51.2mm. The 16 represents 16 x 1/8th of an inch, or 3.2mm x 16 = 51.2mm.
Many caravans and RVs may also use G5 fluorescent tubes. These are usually around 16 mm in diameter and approximately 300 mm (30 cm) in length.
There is also a quad-pin base with two bi-pin pairs. These are used with compact fluorescent tubes that plug into a light fixture with a permanent ballast, such as the interior 12V caravan light pictured below. If you are looking for a 4-pin fluoro with ballast, match the tube base and check whether the ballast is part of the light fitting or part of the replacement lamp. If the ballast or holder is damaged, replace the fitting or have it checked rather than guessing from the tube alone.
Above: Samples of globes that use the Bpin system. Additional forms are listed on our website.
Festoons are an automotive standard bulb available in 6V to 60V configurations. In caravans and RVs, they are mainly used in 12V clearance and marker light applications.
They are measured by length and by the width of the glass. There are a number of sizes available, ranging from 6.5mm to 15mm in width and 24mm to 44mm in length. Wattage is normally printed on the metal cap ends.
Caravans Plus recommends using bayonet or fixed LED for auto lights where suitable, because vibration can affect the reliability of festoon connections and filaments.
These low-voltage bulbs have become common in the automotive industry and have carried through to the caravan and RV industry.
They work in a similar way to the Bi-Pin system, but have a sturdier base and the wires run inside the globe itself. The body that holds the bulb in place is spring actioned, ensuring a positive grab. Wedges may also be double filament.
Wedges are commonly found in many Australian built caravans, including Jayco, who fit the Narva internal ceiling light systems.
By far the most common size is the T10. Always use a bulb of the same candle power to ensure the bulb does not burn back into its housing.
Great service Quick refund on the wrong part ordered. Correct part reordered and received 2 days latter. Great company to deal with.
Very good service and delivery time.
Great service from the staff