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Posted By Topic: Permanently wired USB module

Mar 09 2020 11:36

A client wants me to install about 10 'direct replacement' vertical 10A sockets with new ones containing a USB power supply. The supply is a module permanently attached to the rear of the socket and has a pair of supply wires hanging out. There are two moulded-in switches - one for each of the sockets so none to seperately switch this power supply.

My query is should this not be switched? If not then it's permanently on.

Mar 09 2020 13:59

Interesting point arising from this question: is a USB a socket outlet?

Also a wider issue, that "3000" is mostly written from an LV viewpoint, and assumes LV unless otherwise stated. Yet there is no such limitation in Scope; and ESRs require ELV aspects of installations to comply with "3000". of 2018 edition forbids comms/data/etc connecting devices from being on same faceplate as a "fixed switch or socket outlet" ; clearly intending this to refer to LV switches / sockets.
And the note then refers to USB socket outlets" as being acceptable.

My reading of this is that such USBs are ELV sockets. In other applications, USB may also be a communications connection; but where that is the case, they are NOT permitted to be on same faceplate as any LV accessory.

ELV sockets must comply with 4.4, and also comply with subsection 7.5.
Clause 4.4.4 requires all sockets to have a switch (with some exceptions). Nothing in 7.5 creates any special Exception allowing an ELV socket to not have a switch. So my view is that if you want to put a USB (charging-only) unit on same faceplate as LV accessories, then it has to have a switch.
Not that such switch would serve any safety function; just that when introducing the ban on same-faceplate mounting, along with the note (which should really be an Exception); not enough thought was put into the consequences.

Like the switching requirement; and the fact that USB doesn't match the list of permitted socket formats in

Overall; I'd say that these pre-manufactured units may comply with product Standards, but can't be installed to comply with "3000" unless a switch is provided, i.a.w 4.4.4.

Exception 3 won't apply. Exception 2 may apply in some (rare) cases.

On the other hand, it's unlikely anyone will ever complain about such non-compliance.

Mar 09 2020 22:12

Thanks Alec - my primary concern is that if I fit these without a switch and any of them go up in smoke (as they will be on 24/7) then theoretically, the clients insurance could throw it back at me.

Mar 09 2020 22:19

I haven’t installed many USB combined socket outlets but the ones I’ve installed have all been hard wired into the back, namely PDL 693USB and Legrand Excel Life series.

Mar 09 2020 22:20

* 692USB

Mar 09 2020 23:39

I can't see how so many manufacturers are producing and certifying these USB power outlets without switches, if they actually required switches.

Mar 10 2020 08:51

I don't believe a switch is needed in any practical sense for an ELV socket; but given the wording of both current & 2018 Wiring Rules I believe one is required , purely from a compliance viewpoint. That's an installation requirement, not a manufacturing one.

Many parts of "3000" & companion Standards seem to have a sort of tunnel vision. They cover both LV & ELV, but in many places that seems to be overlooked.
They also have tunnel vision WRT normal supply being from an external distribution network.