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Note: this is entirely theoretical. I have no (current) plans to actually do this.

Would I violate any state/national building/electrical codes if I installed BS 1363 (UK plug/socket) sockets on a 240v circuit in an ordinary residence? In addition to the existing 120V circuit with NEMA sockets.

For the sake of the question, assume that the goal is to wire the 240V sockets as closely to the way they'd be wired in a UK house as possible. (mostly with respect to safety features)

Failing that, what features of a standard BS 1363 outlet can I implement which differ from a permanently-attached NEMA-6 to BS 1363 adapter?

And most importantly; What are the safety implications of installing/using a setup like this?

Inspired by this question about running 240v circuits and looking into the NEMA plug types available in the US.

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    I suspect the main issue would be that the devices won't be listed/tested by the appropriate certification agencies for this side of the pond. This is not to say that they are unsafe, but the tests and agencies doing them differ, so that part of code would be an issue. Minor nitpick - nominal USA/Canada supply voltage is 120/240 VAC virtually everywhere, so 110 is outdated or means you are having a brownout. – Ecnerwal Dec 27 '19 at 3:09
  • +1 for acknowledging a testing agency must approve listing. @Ecnerwal If this was an answer, I’d upvote. – Lee Sam Dec 27 '19 at 3:35
  • @Ecnerwal Do you mean certification on devices to be plugged in, or devices to be permanently installed? (I'm assuming a non-certified device plugged into an outlet doesn't decertify the house's wiring.) – bobsburner Dec 27 '19 at 3:40
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    That's one case where a CE mark will not cut it. BSI on the other hand... maybe. – Harper - Reinstate Monica Dec 27 '19 at 8:28
  • Also consider if the device had any sort of timer. I think the UK uses 50hz, while the US uses 60hz. The frequency difference would change timer operation and may affect some switch mode power supplies. – Eric Simpson Dec 27 '19 at 14:00
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Mutually Incompatible Certification Schemes

The primary problem with what you describe (installing a foreign-standards receptacle into a North American electrical system) is while foreign receptacles of reputable make (vs. some Cheese-pipeline special) are going to have a third-party certification, that certification is going to stem from a different certification scheme than the OSHA NRTL (Nationally Recognized Testing Laboratory) scheme we have in the US. For your BS1363 receptacle example, the third-party certifications for these receptacles are going to come from an IECEE (IEC System for Mutual Recognition of Test Certificates for Electrical Equipment) Certified Body (the European analogue to a US NRTL), as seen in this example for a Legrand Arteor BS1363 receptacle. Most US Authorities Having Jurisdiction (AHJs, aka local building inspectors) will not recognize such a certification without prior research and written agreement (at minimum, some may simply flatly refuse to recognize anything that does not fall within the OSHA NRTL scheme), just as Building Standards in the UK isn't going to wave through say an Intertek ETL listing as "approved" without looking into things further.

Parts do exist for this...

However, amazingly enough, there is such a thing as a switched BS1363 receptacle on a North American yoke; I contacted Leviton tech support, and while you'd have to contact them via email or webform I presume to obtain the certificates, the tech support contact did indicate that the part linked has a third-party certification through the IECEE scheme, so it wouldn't be a completely lost cause for a written AHJ variance.

...but likely aren't needed, either

However, most appliances intended for use with BS1363 plugs either come with a stripped/tinned cord end so that the appropriate plug can be fitted, or use an IEC appliance coupler and mating detachable power cord. In these cases, there's no reason to use a foreign receptacle type when the appliance can simply be fitted with a NEMA 6-15P instead; even if the original cord and plug was hard-wired on, chopping the plug off, stripping back the cord, and field-fitting a NEMA 6-15P would be more reasonable than trying to go through the hoops of getting an AHJ to sign off on having foreign receptacles permanently wired into one's house.

As to that L-L vs L-N thing...

There are two other differences between US 240V and IEC 230-240V as well; while mains frequency (60Hz vs 50Hz) is one of them, it's not feasible to convert between the two, and fewer and fewer appliances are frequency-sensitive in this day and age due to the replacement of electromechanical drum timers and capacitor-start AC induction motors with electronic controls and inverter motor drives. In any case, if the appliance says "50-60Hz" or "47-63Hz" on its nameplate, than it has been tested to run on both mains frequencies and will not have an issue with the change.

The other difference is that US 240V power is Line to Line (two hots and a ground), while IEC-style 230-240V is Line to Neutral (hot, neutral, ground). While a NEMA-style dry-type distribution transformer can be wired to convert between the two, the use of 240V-to-ground power in the US requires that 240V straight rated breakers be used for overcurrent protection (vs the 120/240V slash rating found on standard North American circuit breakers). The good news is that 240V straight rated breakers are made, although their availability depends on which make/model of panel you're using (offhand, Square-D Homeline is the only panel line that does not have straight rated 240V breakers available for it); however, special functions such as GFCI and AFCI are not available in 240V straight ratings, which puts a hard limit on where this adaptation can be done.

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  • I'm a little unclear on what parts of each standard are mutually exclusive. Also, does inserting an adapter (NEMA 6-15P socket -> BS1363 socket), which has the same electrical effect as rewiring the appliance to NEMA 6-15P count as permanent wiring? (Was the stupid-workaround I thought of when formulating the question, but now know to avoid for safety reasons) – bobsburner Dec 27 '19 at 19:14
  • @bobsburner a plug-in adapter does not count as permanent wiring, no. As to the standards, the problem is not that the standards are mutually exclusive, but the certification schemes aren't recognized outside their normal range. – ThreePhaseEel Dec 27 '19 at 19:16
  • Even if the adapter were very difficult to remove from the certified socket? (e.g. by being recessed into the wall) Is there no general certification process that can cover outlet types that aren't already listed? (i.e. a cert allowing the installation of an arbitrary number of the sockets, in a specific manner, with the sockets all being of the same design.) If such a process exists, is it per location, per applicant, or per design of socket? – bobsburner Dec 27 '19 at 19:28
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    None that you can wave in a denying AHJ's face and force a concession on the point. The AHJ can always allow it. – Harper - Reinstate Monica Dec 28 '19 at 0:58
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There is no listing for non-standard receptacles, so at a basic level, it would require "examination" by the AHJ (Authority Having Jurisdiction) in your area under NEC Article 90.7 to make sure it doesn't violate the basic "suitable for use" rules in Article 110.3. You might find an AHJ who will accept the IEC certifications as adequate, you might not, there is no way to know in advance. Most states have specific rules as to what third party listing agencies they will accept, often deferring to a list maintained by OSHA, referred to as the NRTL (Nationally Recognized Testing Labs) list. But unfortunately, most IEC devices do NOT undergo testing by any third party listing agency, manufacturers can "self certify" to any applicable standards, something that we in North America don't accept. I would venture to say that MOST inspectors here are aware of this and will not accept IEC devices, but again, you can't know without asking THE one that is going to inspect your house.

All of this is predicated on you having it inspected at all. If it's just you living in your house, you can do what you want. But if there is a fire, injury or loss associated with the device, your insurance company may use the unauthorized installation of it to avoid having to pay damages. Then when you go to sell your house some day in the future, you would have to remove the devices or disclose to the buyers that there was unpermitted electrical work done, something that scares a lot of people.

Another aspect is the equipment you intend to plug into this device. First is the 50Hz / 60Hz issue; if there are any motors inside, they may not work correctly. Then there is the fact that 240V here in North America is Line to Line, 230V overseas is Line to Neutral, with the Neutral referenced to Earth (ground) the way we do with 120V. While normally they would have the Neutral and Earth separated, in rare occasions the Neutral of equipment is bonded to earth inside. In that case, it's impossible to connect it here, it would be a dead short to ground.

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  • Note that there are processes in the European system akin to our NRTL listings (for the OP's receptacles, they'd be looking for a BSI certification, for instance), but you are right that North American AHJs would be unfamiliar with them and thus would need quite a bit of documentary evidence to accept such a foreign third-party certification – ThreePhaseEel Dec 27 '19 at 5:25
  • For instance, take a look at this Legrand Arteor BS1363 socket, under the "Certificates and Agreements" section – ThreePhaseEel Dec 27 '19 at 5:35
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    I know you're not making a blamket stayrment, bit I wouldn't say "if it's just you, you can do anything you want". There are still stakeholders. The mortgage lender needs to be protected, so they require insurance. The insurer has the right to require prudent behavior on your part (or cancel coverage, meaning the note gets called). The city has a stake since it's their fire trucks that'll roll. And to protect community standards, they get to disallow hovels. – Harper - Reinstate Monica Dec 27 '19 at 8:58
  • TUV is an NRTL... but I don't see a switch in that outlet @ThreePhaseEel ! Firetrap, clearly :) – Harper - Reinstate Monica Dec 27 '19 at 9:03
  • I presume by device, you mean the socket itself. Is it at all possible to get a specific socket design tested by a recognized testing lab? (I presume they'd refuse for one of their own reasons.) I also assume it'd be unworkable to adapt phase-phase to phase-neutral on a circuit or socket level. That bootleg ground setup you describe at the end of your answer terrifies me. – bobsburner Dec 27 '19 at 13:20

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