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Posted By Topic: RCD

michael
Apr 20 2018 12:09

Hi there, sometimes I have situations where I need to install a double power outlet under a house for a gas heating system.If RCD on sw bd all good if no RCD on sw bd I will hardwire it,no problem. But a certain brand has a touch pad now that has a transformer plug feeding an interface board, so I can't hardwire that.
So sure I will fit an RCD on the board if I have room and posible but if I don't, i can fit a PDL rcd point next to furnace.Not very convenient for resetting I know but limited options in some cases.Now my question is if I can do that am I able to put a din rail mounted RCD in one of those plastic 2 way enclosures on a joist by the furnace and feed a double point off that? Would be half the cost of an RCD point.
   

AlecK
Apr 20 2018 13:02

It should be possible to work out a compliant set-up using an RCD plus an enclosure. The fact of there being a remote (ie not switchboard-mounted) RCD should be recorded at the switchboard.

However you appear to have overlooked the requirement [4.18.1] for gas appliances to have "means of isolation adjacent. Where you use a socket outlet, that's taken care of (isolation by unplugging); but when you hard-wire you need an isolating switch. A PCU or similar ordinary type switch is NOT compliant.

   

michael
Apr 20 2018 13:12

Yeah we have discussed the hard wiring before but no one has come up with a suitable isolator for an inbuilt gas fire,sure I can use an isolator under a house.
   

eurotech
Apr 22 2018 16:59

Hi Michael, isn't the requirement for gas appliances just double pole? That should be easy to source
   

pluto
Apr 22 2018 17:10

eurotech Apr 22 2018 16:59
Your comment
Hi Michael, isn't the requirement for gas appliances just double pole? That should be easy to source

My comment
In NZ only, single pole isolation in the active conductor is required.

The use of a switched socket outlet (can be any decent looking one available in NZ) can provide the control switch and the withdrawing the gas heater plug from the socket outlet will give the isolation required for the servicing of the gas heater.

However, the socket outlet will require an RCD if in a domestic installation to comply with clause 2.6 of as/nzs 3000.
   

Dannyboy
Apr 22 2018 20:19

It sound like this is a gas fire built into the internal wall of the house if this is the situation we just hard wire this into a near by power outlet with an extra switch which I believe complies and if it is too far away we just put a lockable switch in the socket.
   

pluto
Apr 22 2018 22:36

Dannyboy Apr 22 2018 20:19
Your comment
It sound like this is a gas fire built into the internal wall of the house if this is the situation we just hard wire this into a near by power outlet with an extra switch which I believe complies and if it is too far away we just put a lockable switch in the socket.

My comment
The extra switch on the socket outlet does not comply with the requirements for am isolating switch. thus it does NOT comply with AS/NZS 3000.

Clause 4.18.1 subclause (a) gives an acceptable solution.

Subclauses (b) and (c) require a switch fully complying with Clause 2.3.2.2.1 of 3000.

The switch requires an impulse voltage rating which can NOT be obtained from control switches used on socket outlets.

PS the removal of the gas heater plug from the socket outlet provides the required impulse voltage rating isolation.
   

AlecK
Apr 23 2018 09:03

The fact that it is required to be a "means of isolation" means that if a switch is used it must be an isolating switch; which as pluto says has to comply with 2.3.2.2. Nothing that uses clip-in "micro-gap" switch mechs complies.

Unfortunately all isolating switches have an industrial look to them. In many cases this doesn't matter much, but for a gas fireplace you'll either have an ugly isolating switch or a flex & plug for connection to a socket.
   

michael
Apr 23 2018 13:41

So if a functional switch on the outside wall feeds an RCD protected socket on the inside [behind the fire] and that is compliant.Could you then say a functional switch which feeds an isolator switch on the inside,which the flex is wired into is also compliant.
   

AlecK
Apr 23 2018 16:07

In that scenario the "means of isolation" would be the socket - and it is NOT allowed to be behind the fire. The means of isolation must be adjacent to the gas appliance, and accessible with the appliance in its installed position (so NOT behind the fire).

If you upgraded the external switch to an isolating switch, then the socket behind fire would be OK - but the switch would NOT be "adjacent".
   

michael
Apr 23 2018 16:18

So there is no acceptable way then, short of using an industrial looking isolator.
   

gregwires
Apr 23 2018 16:19

Could a functional switch (next to the fire) that operates a remote contactor be a solution? (Just thinking aloud)
   

michael
Apr 23 2018 16:21

na not considered an isolator.
   

michael
Apr 23 2018 16:22

didn't read your post fully I would say yes but what a lot of mucking around.
   

michael
Apr 23 2018 16:24

Although it still can't be locked off.
   

gregwires
Apr 23 2018 16:26

After more thing, a contactor would be hard to secure open so not an option.

   

AlecK
Apr 23 2018 19:06

Rest assured that the manufacturing sector is looking at this issue; I'd expect that they'l bring a 2P isolating switch-on-wall-plate to market but there are technical issues for them to work through.
   

mowgli
Apr 30 2018 22:53

The rules say that the isolating switch had to be "accessible" and "adjacent". They don't say it has to be in plain sight. Has anyone tried putting it in an adjacent cupboard or behind a hinged cover of some sort?
   

AlecK
May 02 2018 10:03

Currently neither of those terms is defined in clause 1.4.
Both of them have definitions in the new edition:
Accessible
Capable of being reached for inspection, maintenance or repairs but
does not include the destructive dismantling of structural
components.
Adjacent
Next to or adjoining without obstruction and within arm’s reach.

putting it inside a cupboard would not be "without obstruction".
   

Andrew
May 02 2018 10:36

Just a thought - an RCD would be an isolator, so wouldn't using a locally mounted RCD as your isolator meet the requirements?
   

Satobsat
May 02 2018 11:01

So how do they go on when they install gas fires in outdoor damp environments such as bars and restaurants I don't think I've ever seen one with an accessible isolator adjacent to the fire? Could be wrong though.

   

pluto
May 02 2018 11:41

Just for information only with the view it could be adopted here in NZ.

Under the IEC 60364 (international wiring recommendation or the BS7671 (UK Wiring rules) both use the fact that as in AS/NZS 3000 clause 4.18.1 (a) provides for by using a switched socket outlet and plug connection from the gas appliance.
The switch on the socket outlet provides a "control"switch and if "isolation" is required, the plug is removed from the socket outlet.

Another factor to remember under the IEC and ES Wiring Rules; the removal of the plug (up to 16 A max AC only)for the socket outlet when alive is considered as meeting the rules for an isolating switch.

The solution for NZ simply comes back to providing a switched socket outlet (can be any approved fancy or good looking ones made by most manufacturers) and a matching 3 pin plug is a solution able to be done today by buying ther correct fittings.

This arranghementalso allows gas fitters to work safety to replace any internal electrical components if they have electrical registration.
   

Satobsat
May 02 2018 13:18

What about running the flex inside a wall to a Single outlet plug with a PCU mech mounted instead of an auxiliary switch and have the flex exit the wall through the PCU mech then plug into the socket? This way it is accessible and meets the requirements for control and isolation whilst looking reasonably tidy?
   

pluto
May 02 2018 13:53

It needs to readily accessible to be able to withdraw the plug horizontally (AS/NZS 3000 clause 4.4.2.2 refers) I'm not sure that your proposed arrangement does that.
   

michael
May 02 2018 14:13

Pluto, are you saying a gas fire installed in an old wood burner cavity has to have a lead passing out the front and plugged into an adjacent power point is the only way to isolate it.
   

michael
May 02 2018 14:25

If so that will never be accepted considering the costs involved in supply and installation.
   

Satobsat
May 02 2018 14:34

No the flex has a loop on it coming out through the PDL PCU mech (651M2 with the terminal block removed) mounted on a PDL 694X installed adjacent to the fire in an accessible position.

Remove the fitted plug from the flex lead or the flex lead from the appliance feed through the 651M reconnect the flex to the appliance or fit a PDL 901 side entry plug.

The plug can be removed from the socket as long enough of a loop is left.
   

michael
May 02 2018 14:46

Sounds practical enough but someone who is spending between 7-10k on a fire is not going to accept that.Didn't think you could pass a flex through a wall cavity anyway.
   

Satobsat
May 02 2018 14:57

AS/NZS 3000:2007 3.9.4.7 Flexible cords used as installation wiring Exceotion(c) which asks to sight 4.3.5
   

Satobsat
May 02 2018 14:59

I'll try that again

AS/NZS 3000:2007 3.9.7.4 Flexible cords used as installation wiring Exception(c) which asks to sight 4.3.5