UK to US travel adapters appear to swap Neutral and Hot

[Alchemist]

Examining multiple commonly available travel adapters which allow using devices with US plugs in the UK, it appears they swap the hot and neutral connections. This does allow a simple "straight-thru" wiring of the adapter, but does it raise any safety concerns? I've verified the wiring with an ohm meter.

Example here

 

[LarryFine]

Welcome to the forum.

Can you explain what you mean? Perhaps a diagram?

I now of two types of EU-to-US adapters, transformer and diode; only transformer works the other way.

 

[Alchemist]

The travel adapter does not adapt the voltage, it only works with US devices capable of both 120V and 240V operation. If my understanding is correct, looking at the photo of the adapter, the UK Neutral pin in on the right (rear), but the US pin on the right (front) that it connects to is the Hot.

 

[LarryFine]

Aha. I wasn't aware of the UK polarity. Fortunately, most products are not polarity-sensitive anymore.

 

[David Castor]

It does seem odd. But normally these are used to connect dual-rated switching power supplies for electronic equipment such as cell phones and computers, so in that application I don't see any real safety issues. When I was in Ireland, it was a little disconcerting to plug my little iPhone cube power supply into 230 V via the adapter, but no problems.

I believe these "Type G" plugs must include an internal 13 A fuse in the hot leg.

 

[jaggedben]

I don't see how the UK plug is polarized. Or do all plugs there have the third prong?

 

[David Castor]

The 13 A Type G has line, neutral and ground. It's polarized only by the relative positions, I guess. The Line and Neutral stabs are identical, AFAIK. I believe there are lower amperage types that only have two prongs.

 

[LarryFine]

I don't see how the UK plug is polarized. Or do all plugs there have the third prong?

It's polarized in the sense that the grounded conductor (it's a wye supply) is always on the same side, but not the same side as ours, so the adapter makes our grounded side hot, which doesn't really matter these days.

 

[jaggedben]

It's polarized in the sense that the grounded conductor (it's a wye supply) is always on the same side, but not the same side as ours, so the adapter makes our grounded side hot, which doesn't really matter these days.

That's not what I meant. In the US, modern two prong plugs are polarized by having a larger neutral prong, which can only fit into the neutral slot on a polarized receptacle. So the appliance cannot be plugged in backwards (whether or not it actually matters which conductor inside is grounded). I don't see a corresponding feature on the UK plug, the grounded and ungrounded conductor prongs/slots look the same, like a plug without a third prong could be flipped.

 

[electrofelon]

The travel adapter does not adapt the voltage, it only works with US devices capable of both 120V and 240V operation.

Really? That seems like a really bad idea. So those things put out 230V to a NEMA 5-15 recep?

 

[jim dungar]

Really? That seems like a really bad idea. So those things put out 230V to a NEMA 5-15 recep?

Most travel "adapters" simply change the plug and receptacles.
You need to use a voltage convert or if your device cannot accept the foreign voltage.

I have been using an adapter for at least 15 years, I have used it in Ireland, Scotland, England, Spain, Italy, France and several cruise lines. Mine does include a 5V USB port as well as the power receptacles. I make sure all of my travel devices, particularly razor and toothbrush, use some type of switched mode power supply so they are good from roughly 100-240V.

 

[retirede]

Really? That seems like a really bad idea. So those things put out 230V to a NEMA 5-15 recep?

Yes, that’s exactly what they do. I travelled in Europe quite often over the years and always used these to power my notebook PC. The switching power supply was rated 100 - 250VAC.

We had an interesting event once in Finland when staying at a hotel that charged something like 50 Euros per day for wired high speed internet. The networking guy traveling with us had the idea to bring along a wireless access point so we could all share one connection. He forgot to look at the power supply spec. It was only rated at 120V and he initiated a magic smoke event when he plugged it in.

 

[zbang]

I don't see a corresponding feature on the UK plug, the grounded and ungrounded conductor prongs/slots look the same, like a plug without a third prong could be flipped.

The modern UK receptacle would be considered "tamper proof" and requires a grounding pin long enough to push open the shutters over the hot/neutral slots; in my recent visits, I never saw a 2-prong plug but I did see a bunch of 3's with a plastic grounding pin.

When I travel there, I use a UK adapter to a short US extension cord and plug everything (all multi-voltage, of course) into that.