X

We use cookies to give you a fabulous customer experience and enable you to checkout on our website. By continuing we will assume you are happy to receive all cookies, otherwise you can review more information on cookies here

Difference between GU4 & GZ4 and GU10 & GZ10?

The codes for "G Style Cap" light bulbs can seem confusing, the chart below should help to clearly show the differences in the four most popular types (GU4, GZ4, GU10 and GZ10). In order to work out the difference you need to break the code apart. The number following the G is the length in mm between the pins. The U stands for a rounded cap whereas Z means its square.

Obviously a round peg won't fit in a square hole.

**Base****Description**
**GU4**
<a href="https://www.bltdirect.com/halogen-mr11-light-bulbs"><img alt="" src="https://static.bltdirect.com/cache/images/gu4-100x100.jpg" style="width: 100px; height: 70px;" /></a> </td> <td style="border: 1px solid #000000; text-align: center;" valign="middle"> GU4s have a 2 pin rounded base, they are found on reflector lamps. The pins are 4mm apart. They run on 12v and 6v. </td> </tr> <tr valign="TOP"> <td style="border: 1px solid #000000; text-align: center;"> <a href="https://www.bltdirect.com/halogen-mr11-light-bulbs"><span style="font-size: small;">**GZ4**</span></a> <a href="https://www.bltdirect.com/halogen-mr11-light-bulbs"><img alt="" src="https://static.bltdirect.com/cache/images/gu4-100x100.jpg" style="width: 100px; height: 70px;" /></a> </td> <td style="border: 1px solid #000000; text-align: center;" valign="middle"> GZ4s are the same as GU4s except they have a square shaped cap. </td> </tr> <tr valign="TOP"> <td style="border: 1px solid #000000; text-align: center;"> <span style="font-size: small;">**<a href="https://www.bltdirect.com/gu10-light-bulbs">GU10 Bulb</a>**</span> <a href="https://www.bltdirect.com/gu10-light-bulbs"><img alt="" src="https://static.bltdirect.com/cache/images/gu10-1-100x100.jpg" style="width: 78px; height: 100px;" /></a> </td> <td style="border: 1px solid #000000; text-align: center;" valign="middle"> GU10s are the most popular domestic fitting, they have two pins and a rounded base. The pins are 10mm apart. They use a twist lock mechanism when putting in the bulb. GU10s run on 240v, the same as mains electricity. </td> </tr> <tr valign="TOP"> <td style="border: 1px solid #000000; text-align: center;"> <a href="https://www.bltdirect.com/halogen-dichroic-gz10-light-bulbs"><span style="font-size: small;">**GZ10**</span></a> <a href="https://www.bltdirect.com/halogen-dichroic-gz10-light-bulbs"><img alt="" src="https://static.bltdirect.com/cache/images/gz10-100x100.jpg" style="width: 100px; height: 88px;" /></a> </td> <td style="border: 1px solid #000000; text-align: center;" valign="middle"> GZ10s are the same as GU10s except they have a square base. You can use GU10s in GZ10 fittings but not the other way round. </td> </tr> </tbody>

Created by Steve Ellwood on 24th July, 2015

Author

Steve Ellwood

Steve Ellwood

Qualified as an Electrician, founder of BLT Direct , You can follow them here