Imported: bathroom heaters, isolating switch. (4.9)

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DougP
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Imported: bathroom heaters, isolating switch. (4.9)

Post by DougP »

This is an interesting one that people often misinterpret.
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rarrar
Sep 01 2015 14:24


what\'s the correct way to install a golair pull cord heater, does it require an isolating switch or not?

pluto
Sep 01 2015 14:42


The heater pull switch is only classified as a "control switch\" and nothing else.

If an \"isolating switch\" is being called for, a "control switch\" does NOT comply.

So read the 3000 clause and see the type switch being called for.

Some of clauses in 3000 are currently incorrectly calling for \"isolating switch\" when a \"control switch\" is adequate, these errors are being corrected during the 3000 review currently in hand.

rarrar
Sep 01 2015 15:05


4.9.2 (b) isolating switches may be incorporated in temperature control devices, provided they have a definite off position????? will this cover it?

pluto
Sep 01 2015 16:09


rarrar Sep 01 2015 15:05

Your comment
4.9.2 (b) isolating switches may be incorporated in temperature control devices, provided they have a definite off position????? will this cover it?

My comment
The temperature control device is likely to be only an control switch also.

An isolating switch requirements are detailed in 3000 clause 2.3.3.2.1. Have a read and you will find that this device is generally NOT used near fittings being supplied.

Clause 4.9.2 could be considered as one of the clauses in which an isolating switch should be provided near the fitting to enable safe working on the fitting, but from a practical point of view, it will NOT be adjacent the fitting.

There is, however, in most installations, a true Isolating switch on each final sub circuit and that is the over current protective device, typically an MCB in most modern domestic installations, on the switchboard and would be a typical application of the provision in many installation.

To be able to safely work on that fitting (after the supply has been isolated) and to be touching the normally live parts, remember you have lock off and tag, if remote and out of view from your working position, to get true "ISOLATION" using the final sub circuit over protection device.

The new Work Health Safety Regulations will have some surprises coming and this is an typical example.

DougP
Sep 01 2015 16:27


So Pluto,
What\'s your interpretation of 4.9.1 where it states \"an individual isolating switch and an individual functional switch shall be provided for each room heater or for each group of room heaters.\"

So for an installation with say one bathroom wall fan heater, with its own functional switch - does 4.9.1 mean that the heater must be wired separately to an individual circuit breaker?

AlecK
Sep 01 2015 18:50


\"What\'s your interpretation of 4.9.1 where it states \"an individual isolating switch and an individual functional switch shall be provided for each room heater or for each group of room heaters.\"

Exactly what it says, especially when read in conjunction with the following subclauses that give detailed rules for each type of switch.
There must be a isolating switch for each heater / group of heaters.
There must also be a functional switch for each heater / group of heaters.
The most common compliant method would be the pull-cord serves as functional switch, with or without an additional / alternative functional switch for convenience; while the isolating switch is the mcb at switchboard.


\"So for an installation with say one bathroom wall fan heater, with its own functional switch - does 4.9.1 mean that the heater must be wired separately to an individual circuit breaker? \"

No.
I suspect the word "individual" is being misinterpreted.
It just means that each heater / group of heaters must have one. It does not prohibit that isolating switch from also isolating other stuff eg sockets.

But note that you can\'t do this using say HRC fuses, as the requirement is for a \"switch and a fuse does not comply. so in a factory with fuses, you would need to actually install an isolating switch for each heater / group, i.a.w. 4.9.2 AND a functional switch as well. The functional and isolating switches can\'t be combined in one device, because 4.9.1 says one of each.
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