Manufacturers Instructions - New installations

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JamieP
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Manufacturers Instructions - New installations

Post by JamieP »

ESR 59 (3) allows us to use MIs to maintain or replace as an alternative to following 3000

ESR 59 (2) only allows compliance with part 1 or 2 of 3000

ESR 14A allows us to rely on them as being electrically safe in certain situations outlined in (a) and (b)

But can we use MIs as an alternative of compliance in new installations?

My question comes from the fact that many inverter manufacturers now specify RCD protection on the grid AC side of the inverter and although 4777.1:2016 allows this and tells us to follow MI recommendations (3.4.5), 4777.1:2005 the cited version doesn't allow RCD protection as per 5.3.4 and note 1 also confirms this on Figures 1, 2 and 3 (understand these aren't requirements but backs up the clause)

So clearly RCD protection is a good idea as both the manufacturers and the more up to date standards allow it

But can we use the MIs to get around the fact that if we ESR 59 (2) and follow part 2, ESR 60 (2) says we must comply with 4777.1:2005 or can MIs not get around this?

If we can't, is the only option a part 1 design in accordance with ESR 59 (2) if we wanted to go down this route?
AlecK
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Re: Manufacturers Instructions - New installations

Post by AlecK »

Short answer: No.

But I think you're confusing two different requirements.
True they both relate to RCDs; but they're about different RCDs installed for different purposes.

In 2005 edition; 5.3.4 requires that an inverter must be connected to the installation upstream (on the grid side) of any RCDs that are installed in that installation.
In other words, don't connect the inverter to an RCD-protected subcircuit downstream of the RCD; for the obvious reason that if you do the RCD can't offer any protection to the subcircuit while the inverter is supplying power.
This is solely about which point in an installation the inverter can be connected to;
and there's no change in 2016 edition.

Clause 3.4.5 in 2016 is about using an RCD for "mechanical protection" of the inverter feed-on cable (as per 3.9.4.4 of "3000").
The RCD is installed at the swbd end of the feed-in cable; so it only provides mechanical protection for current originating from the grid
Which is OK; as a grid-connected inverter can only be a supplementary supply and is required to include anti-islanding so it can't act as a source in absence of normal supply.

There may appear to be a compliance issue ; in that the inverter isn't "on the grid side" of an RCD that's in the inverter output cable.
However the clause doesn't refer to where the inverter is connected; it refers to where the "inverter energy system" is connected to the (rest of) the installation. The IES includes more than just the inverter; it also includes any sources supplying the inverter, controls, and grid protection devices. And, presumably, the interconnecting cable - not specifically included, but not excluded either.
So reasonable to consider that the IES extends to the point of connection to (rest of) installation

I'd agree that much of this stuff could have been written far better.
Perhaps reflecting a dominance of technical 'inverter' people on the committee, with not enough 'installations' people?

But I don't see any material conflict between these two aspects;
so no need to consider trying to use MIs to get around specific requirements.
Not that that's possible; because ESR 14A requires MIs to result in an installation that's both safe and compliant.
JamieP
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Re: Manufacturers Instructions - New installations

Post by JamieP »

5.3.4 in 2005 is worded so confusingly, I see what you're saying though

The way it says "grid side of ANY RCD" and the way the notes backed that logic up with the fact they indicate "An RCD is not to be placed between the consumers mains and the solar supply (see Clause 5.3.4)" still makes me feel like I can't have any RCD there

And that last part makes sense, I take it this is why there are only the 2 options under 59 (2) because by default, MIs should be written for compliance with the standards we follow anyway and not conflicting
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