Gas cooker, hob, and oven flexible pipe connections
Gas cooking appliances are typically connected to the supply in domestic premises via either rigid pipework or via a "plug-in" flexible hose that connects to a self sealing "bayonet" connector fixed to the fabric of the building.
A common question raised concerns whether the use of a flexible connection is acceptable for use with a gas hob, with people (often including professional gas fitters) claiming that its not acceptable.
There are some often repeated misconceptions, that this article aims to clarify.
The regulations in this area are derived from a British Standard document BS 6172, "Installation and maintenance of domestic gas cooking appliances (2nd and 3rd family gases)"
The wording in BS 6172 (from versions from 2004 onward) state:
"11.1.3 A gas hob shall be connected to the termination point by means of rigid pipework or, unless stated otherwise in the manufacturer’s instructions, a flexible connector and self-sealing plug device conforming to BS 669-1"
So it is fully acceptable to use both rigid or flexible piping on gas hobs. The only exception being where the manufacturer of the hob has stated in the installation documentation that the use of a flexible connection is not permitted.
So why the confusion?
There is a (very) old version of BS 6172 dating from 1982, that prohibited flexible piping for use on built in ovens and "drop-in hotplates" (i.e. hobs). It contained the wording "Built-in ovens, drop-in hotplates and other individual units should be connected to the installation pipe by means of rigid or semi-rigid gas connections. Appliance flexible connections of the type used with gas cookers are not appropriate for these appliances since they are not intended to be movable by the customer."
To complicate matter further, there are some manufacturer's instruction manuals that quote the above out of date regulation, and hence must take precedence over the current rules.