Bonding - gas pipes

[<me9]

I did some line-earth loop testing in my kitchen today. All seemed to be in order, then I thought of supplementary bonding, and realised the cooker hob was not bonded. It is a gas hob,inset in a standard chipboard worktop, with battery ignition, and connected to the gas pipe with a flexible rubber? connector. I checked underneath for any electrical connections, and there were none.

I had just done an earth loop test and it read 0.7 ohms, the adjacent socket was 0.8 ohm. There appeared to be no bonding. Are the quick release gas hoses conductive? They're made of rubber, I would have thought either insulating, or a resistance significantly greater than 0.

[tarquinlinbin]

The flexible cooker hoses actually have a spiral wound steel inner core for re-enforcement and are conductive. I should know,i once plugged one into the gas supply(fitting new cooker) and there was a huge bang and flash. It transpired that some fool had fitted some diy shelves or something and nicked a cable which was plastered into the wall. The new cooker had a power supply for control systems etc and connecting the gas hose provided an earth path via the cooker earth for the stray shorted current.

[Lobster]

Contrary to popular belief (including many electricians) supplementary bonding in the kitchen is not actually compulsory; in fact if you google this newsgroup you'll find posts suggesting that it's actually a Bad Thing.

David

[<me9]

I noticed on reading the IEE website that they now say (very contrary to 15th edition) that an earth free environment is a Good Thing.

Fortunately, whilst working up a ladder in the garage, I was an earth free environment, when I deliberately touched a live conductor, without realising (or noticing) it was live. I had a feeling I'd re-fitted it's fuse, and on re-checking it had been live when I touched it.

[PeteZahut]

I may be wrong but isnt it against the regs to have a hob connected via one of those flexible hoses anyway?

[Lobster]

Yup - missed that when I replied last time! David

[Sparks]

Does this still stand if the hob was installed before this was against the regs then?

Sparks...

[Ed Sirett]

As an electrical appliance (assuming it has mains driven ignition like

99%+ have) it will be a Class I unit and must be earthed through it's supply lead.

The gas pipework will also be earthed near the meter/point of entry.

AFAIK there is no further requirement for any further earthing.

[Sparks]

I was wondering about flexible pipes, our hob had one up until about three weeks ago (We replaced the hob, now it is connected to copper)

If a hob was installed with a flexible pipe when they were allowed, do they have to be removed and replaced?

Sparks...

[<me9]

It was a battery ignition hob, no mains involved, which I had forgotten about when I earth loop tested it. That's why I queried the flexible hose being conductive, as it showed a good earth, presumably due to the gas pipe being bonded.

[dmc]

When we looked into this 4-5 years back it was apparantly ok to use a flexable hose if and only if the hob manufacturer said it was ok in the installation instructions.

Even then there were pretty strict (obvious) rules like making sure the hose doesn't rest on top of anything, making sure it doesn't get hot (from oven etc) etc.

May have changed since (or we may have been given rubbish info at the time!)

Darren

[<me9]

There is nothing in the installation instructions regarding using a flexible hose. It was installed in 1988. Was flexible hose allowed then? It was plugging in to an existing point which had previously supplied a free standing cooker.

The oven is on a separate flex in another part of the kitchen, Its instructions give details for using a flexible hose. A separate point was fitted for it in 1988 when it was installed.

[Andrew Gabriel]

They were allowed on fixed hobs until November last year (providing the hob didn't require a flue, which is unlikely unless you have a commercial kitchen). My parents had a Smeg (IIRC) hob installed in

1999, and the instructions for that do suggest a flexible hose (as one possible option, not as the only allowable method).