Switchboards and additional enclosures

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JamieP
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Switchboards and additional enclosures

Post by JamieP »

At what point does a separate board or enclosure become a different switchboard or an enclosure that's not part of the associated switchboard

This is something that's confused me for a long time, for example if I add a small switchboard beside an existing one I believe this is still part of the same switchboard but at what point does it become its own DB?

Same with enclosures, at what point does it go from being a part of said switchboard and to simply being a stand alone enclosure?
AlecK
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Re: Switchboards and additional enclosures

Post by AlecK »

Good question.

If there's any gap between; then how that gap is bridged would be a deciding factor;
If it's just Actives, and all the Ns go to a common N-bar along with the Ns from the other cabinet(s); then clearly NOT a submain so must be treated as an additional enclosure of same swbd.
If it has A(s) + N, with a dedicated N-bar in the extra cabinet; then could be seen as submains. But submains to a swbd in same structure must also include a PEC (PEN is allowed only for an outbuilding) - so that would mean it can't be treated as a separate swbd unless the "feed" to it includes both N & E; and the extra box has its own N&E bars for the circuits originating from it.

But I believe if they are touching, there's no question that it's anything other than a single swbd comprised of multiple enclosures.
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DougP
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Re: Switchboards and additional enclosures

Post by DougP »

If the actives of the supply to the second enclosure, comes directly from line side actives in the first enclosure, then the supply to the second enclosure is not a submain.
1.4.89 - submains. (in part) .... "...at the load terminals of the circuit protective devices provided within or on a switchboard specifically for the connection of the submains."

If there's no protective device for the conductors, then it can't be a submain, so it can only be part of the same switchboard.

I don't think the N or E bars are relevant, as there can be as many separate N or E bars (suitably connected) in a switchboard as you like.

Just because the enclosures might have a stud width between them (or much more), and separate covers, shouldn't make any difference.
AlecK
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Re: Switchboards and additional enclosures

Post by AlecK »

Good point about the lack of protective device(s) meaning it's not a submain
In similar way, lack of N conductor & PEC conductor means it's not a submain.
And if the supply to an enclosure is not a submain, then clearly the enclosure can't be a separate swbd.

But while things like these may lead to a definite decision that the connection is not a submain (and so enclosure is not a separate swbd);
in many cases it may not be possible to make such a definite call. In such cases I believe it comes down to designer's intent.

A swbd is defined in terms of including "circuit protective devices" for "one or more submains or final subcircuits".
So some would say that any enclosure having such devices must be a "swbd" - but there's nothing to say that a swbd can't have multiple cabinets, so that argument doesn't hold water.

Just the fact of having protective devices doesn't automatically make an enclosure a swbd.
Prime example being a CPD in meter enclosure for a controlled / different tariff "mains".
The devices have to be for the protection of submains / final subcircuits.
Even then, not all protective devices on such cabling are "circuit protective devices"; sometimes they only protect part of a circuit.
2.5.1.3 requires an overcurrent protective device at origin of every submains and every final subcircuit - that's the CPD.
But the clause also requires further overcurrent devices for reduction of CCC part-way along the circuit; and those can't be "CPDs".
They're just meeting the requirement for additional devices part-way along the FS. But some people will look at such a device and declare that the cable supplying it is a "submain", the device is a "swbd" , and the FS starts at the 2nd device.

Another example is tee-offs from a rising submain feeding swbds on each floor.
The tee-offs will generally be in smaller cable than the riser, ie a reduction of CCC;o default is that overcurrent devices are required at these points (however various Exceptions may over-ride that default requirement).
Assuming devices are fitted at tee-off, some will see them as being a "swbd"; others not.
And that difference of interpretation dictates what other rules apply.

The Wiring Rules can't cover every possible configuration in full detail. There are some parts of them that come down to interpretation; and there may be two (possibly more) equally valid interpretations of a particular configuration. Sometimes there's no reason why one interpretation has to be "right" and the other(s) "wrong". What matters then is the intent of the designer / installer. Often the only record of that is the description of work on the CoC. So what you write there could be the difference between "guilty" & "not guilty"

So for adding an enclosure adjacent to an existing swbd, make your call and comply according to your intent
If you say that what you've done is "alteration to an existing swbd; add xxx mcbs on 3 phases" ; and the work complies with all relevant requirements; then that's what you've done - and must be judged by others on that basis and not on their interpretation of what they think you have done / should have done. Similarly of you declare it as "install 3 phase submain to new DB", then that's how the work needs to be treated.

However worth noting that 2018 edition includes a definition for "adjacent"; and I don't think it would be proper to have an addition-to-existing beyond that limit.
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Re: Switchboards and additional enclosures

Post by JamieP »

Thank you as always, appreciate the input
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Re: Switchboards and additional enclosures

Post by AlecK »

I am aware of a case where the work done would have complied as "additional device for reduction of CCC"; but because the installer used the word "submain" on the CoC, it had to be considered in that light.
They then decided that the final configuration didn't comply with requirements for submain to outbuilding;
because they believe - wrongly - that 2.3.4.1 (b)(i) requires a single device to isolate all of the outbuilding.

While that interpretation is clearly wrong; they're the EWRB, so if there's any room for interpretations it's going to be their one that counts - unless you have deep enough pockets to take the argument to district court .

And the original complaint that began the process was because another (ignorant) sparky laid a complaint about something completely different, that wasn't non-compliant.

Which just shows that
a) being fully compliant isn't necessarily enough; and
b) what's on the CoC is a legally-binding declaration.
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