UPDATED – Type reference for Littelfuse 242 series fuse

Intrinsically safe fuse update – 26th November

Sira has received information from Littelfuse that the 242 Series fuse (including the 242.050 used in many intrinsically safe applications) will in future be supplied only as sand filled. The S suffix will not be applied. This will be effective for orders placed from 13 November 2010. Sira requests all clients who have placed recent orders prior to this date to verify the presence of sand filling by breaking open a sample fuse, before installing them in products.


Previous Breaking News – published 6th October

Following on from the previous information published in July (below) please find below an update from Sira:

Provided the Littelfuse 242.050 (50 mA) fuse is sand filled, then Sira will accept the published specification of rated breaking capacity (4000 A). Due to an unresolved issue with type references, clients using this fuse in their intrinsically safe products should confirm that supplied batches of fuses are sand filled. This will most likely mean that a sample of each batch should be opened to verify the filling is present.

The previous information regarding red or silver band markings appears to be no longer valid. The fuse should be ordered with an ‘S’ suffix to the type reference and the presence of sand filling should be verified on delivery.

Previous breaking news – published 27th July 2010

Type reference for Littelfuse 242 series fuse – Important Notice

Manufacturers using the Littelfuse 242.050 (50 mA) fuses in their equipment are advised that, due to the introduction of an alternative construction, the type reference of the sand filled 242.050 fuses now carry the suffix ‘S’.

For intrinsically safe products utilising the 242.050 fuse, manufacturers are required to specify the suffix ‘S’ type as this is identical to the type originally examined under their certification. Sira shall require its client to cease to use the non-sand-filled fuse and instead use 242.050 fuses with the S suffix.

It is not necessary to obtain a variation certificate for existing products as the suffix is additional to the existing type reference specified on the documentation. The change to the type reference can be added when convenient. New projects should specify the 242.050 with the S suffix.

If you have any questions over the above, please contact Sira:

Tel: +44 (0)1244 670 900
Email: info@siracertification.com