Lifeguard units - do they need RCD protection on supply?

[JamieP]

I need to install a socket outlet for a Lifeguard unit supplied via 32A lead. Similar to this https://jackson.co.nz/jackson_electrical/lifeguard-16/

Do these units count as PSOAs?

I was going to apply 2.1.2 (b) as the socket I install will be part of the permanent installation and remain after and then 2.4.6.2 (a)

I'm just wondering if I can apply 2.4.6.2 (c) although I'm unsure if I'd meet the requirements of 2.6.10, the lead used to plug the unit in will be well over the 2m it mentioneds here among other things

[TPower]

Is it used on a construction site? Could you apply Appendix K of 3012/2010, and consider it a ‘detachable submain’.

Most BTS I come across that have a three phase outlet to supply the lifeguards don’t have RCD protection. I’m not entirely sure that’s compliant though?

[gregmcc]

no reason why not, but there may be discrimination issues with the RCD, use a 300mA or a S type with a 100ms delay

[AlecK]

I'm assuming that this is a construction sute, and that your references are to cited edition of 3012.

You seem to have missed 2.4.6.1; which requires all final subcircuits to have "additional protection" by RCD.
your FS is supplying a socket outlet, and none of the Exceptions applies.
So the basic answer is: yes; if you're installing the socket as part of construction wiring, you must provide the protection
(and you can't use a Type S RCD, nor one with RRC above 30 mA, to provide additional protection)

You can't apply 2.4.6.2 (c); as that's for cases of plugging into a pre-existing socket
(as is clearly stated in the Note).

And you can't call something a PSOA unless it meets all the criteria ; 1.4.21 & 2.6.10.

(Noting that 'lifeguard" is a trademarked term), if the unit used complies with "3439.4"; then you can use App K.
Otherwise not.
If it is actually a branded "Lifeguard" by Jacksons, then I am sure it will be an compliant ACS unit.
The concepts and practices permitted by App K have to be applied as a bunch; you can't cherry-pick some aspects.
Note K 4.3 (d) requires the incoming ACS to be directly connected.
So as yours won't be, you can't use App K at all.

But before you leap into shortening that long lead, or other drastic measures;
bear in mind there's no regulatory requirement to comply with "3012".
ESR 25 is a "deemed to comply" Reg; and PA under ESR 75 is only for the installation,
ie the(fixed / ACS) construction wiring, not the 'plug-&-play' equipment.


Back to 2.4.6.2 (c); if the socket is to be part of the finished installation; then it's not construction wiring at all.
So don't bother with "3012 at all.

[JamieP]

Thanks team

Maybe I'm best to break it down a bit more

Correct, construction site, correct cited version, using as a means of being electrically safe

We have provided a Jackson lifeguard unit, the unit is stand alone and a lead plugs directly into it. We have also supplies a 32A lead with it.

Due to no 5 pin 32A sockets in the area, I have installed one from a local DB. As far as I'm aware what I've installed is not temporary construction wiring. It's a permanent part of the installation and installed as such.

Because I want to plug the lead for the lifeguard into this I have installed a 4 pole RCBO to protect the new socket outlet. What I want to know is if I needed RCD protection here or not and if I've made the right call or if because the lifeguard having built-in RCD protection, this was unnecessary. I am aware of discrimination but believe this can't be avoided.

I thought the lifeguard, being equipment on a construction site, would have to be plugged in to an RCD protected supply, this is why mentioned 2.1.2 (b)

[AlecK]

As the new socket is part of the permanent installation, rather than "construction wiring" that will be removed on completion of construction, you can ignore "3012" and just apply RCD protection as per 2.6 of "3000".

There is no requirement for discrimination between RCDs.
Which is probably because it's almost impossible to achieve by means of RC rating.

The fault current that will flow to earth is completely independent of what RCD is used, if any.
so for a "touch active" fault, with human body taken as 1000 ohm, the shock current will be approx 230 mA.
if you have say a 30 mA followed by a 10 mA (as is required for schools), this current is so much higher than the RRC of either RCD
(8 x for the 30mA, and 23 x for the 10mA)
that the chances of not tripping both are small.
So whether you actually get effective discrimination depends mostly on the exact circumstances of the fault.

And yes you can get a form of discrimination by using a type s as the upstream RCD - but it can't provide 'additional protection" against shock.
Nor can any RRC > 30 mA.

So if / when something goes wrong, chances are good that both your subcicuit RCD and the one on the Lifeguard will trip.
So what? It's not like they're hard to reset.
This is exactly what happens with caravans plugged into modern service pillars; 2 x RCDs in line, and generally both trip.

[JamieP]

Understood

But the lead and Lifeguard unit must fall under 3012, correct?

Does it not matter if that plugs into an RCD protected socket outlet or not? Or am I just getting confused

[AlecK]

Yes the Lifeguard unit, including its lead, are within scope of 3012.
But that doesn't affect the socket you are going to install for that unit to plug into,
which is not within scope of '3012".
And since compliance with "3012" isn't mandatory, just go with 2.4.6.2 .

[JamieP]

Understood. Thank you Alec.

Would you mind explaining maybe what the point in 2.1.2 (b) and 2.4.6.2 is then?
I'm not sure if I'm not following or it's going over my head but isn't the lifeguard "other electrical equipment" and 2.4.6.2 would say that I need to supply it from an RCD protected outlet? Although 3012 isn't mandatory, if I did want to follow it, I'd be in breach of this clause if the lifeguard was plugged into an outlet that wasn't RCD proteced

Or am I thinking correctly but because it's not mandatory I shouldn't worry about it, that's what you're trying to get at. That although 3012 calls for it, there is no breach of compliance if I choose not to install RCD protect on my outlet because 3012 doesn't cover that part.

[AlecK]

2.1.2 allows 3 options.

You don't have any "constriction wiring", so option (a) is not available.
If it were available additional protection would have to be i.a.w 2.4.6.1.

You're not planning to use a "standalone power source", so not option (c) either.
If you were; you'd have a choice of additional protection i.a.w. either 2.4.6.3 or 2.4.6.4

You've chosen option (b) supply from permanent wiring;
and this option requires additional protection i.a.w. 2.4.6.2.
this intent reinforced by the heading "... supplied by final subcircuits of permanent installation wiring".
For which there are 3 options,
- RCD at swbd
- RCD at socket (as you've installed)
- PSOA as 1st item plugged into socket

If your Lifeguard qualified as a PSOA, you could have gone with that option. But it doesn't.
So in order to comply with "3012"; you have to choose between installing the RCD for the new socket (or for the subcircuit), or using a PSOA.

Yes; technically under the PSOA option, the PSOA itself is "other electrical equipment";
which could lead to an infinite series of PSOAs, - because each one needs to be protected by one of the three options, .
Clearly that wasn't the intent; and 2.4.6.2(c) should probably have been written as an Exception .

What you've ended up with is compliant; and avoids cutting down the lead (assuming that's the only item that disqualifies this particular Lifeguard unit from being a PSOA.
I suspect very few people would have worried about that detail;
and also very few would have realised that the clause has a glitch built into it.

[JamieP]

Thank you Alec, I think that clears it all up for me

Appreciate your contributions to our industry and for the patience!