Yes, I'm aware of that, but my main interest was in the "all" in my question ...... in other words, I was asking whether they are 'all' as you describe, or whether onw can one get MCBs which 'switch' both poles but sense only one? ... the latter (if they exist) might, for example, interest people who wanted to use the device for 'isolation' in a TT installation)
42 amp supply to 16 amp socket would you pass it with inspection and testing?
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They do exist, generally refered to as single pole-switched neutral (SPSN). Its much more common in RCBOs than MCBs, with many makes of the 'compact' MCBs such as Wylex, Fusebox and Niglon being SPSN, but often erroniously refered to as 'Double Pole' even sometimes on the manufacturers marketing bumpf....
One of the more common times its needed these days is when suppling an EV charge point, where the BS7671 says the RCD protection needs to open the neutral.
SPSN in MCBS does exist but is rather rare, I recall hager do, or at least did make them (it therefore seems strange that initially their miniture RCBOs did not open the neutral - but now they do a separate series which does, you have to be quite careful with ordering if you need SPSN!) and about 15-20 years ago in the rime of dual RCD boards they were marketing the SPSN MCBS to housing associations, with the advantage that tennants could fully isolate a neutral-earth fault to s single circuit by following isntructions from a helpdesk operator with a script allowing for no need to have people on call to go out at unsociable hours as most folk could make do with one cirucit down until the next working day. Never really caught on, and I cannot recall seeing a board with them out in the wild so to speak.
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As Ragnar has already mentioned a neutral switched appears in lists as 1P+N or 1PSN or SPSN. I have only knowingly encountered one once as A submain feed, when trying to replace it I struggled to source a replacement and even then offered an unacceptable long lead time, in the end I used a standard DP unit.
2 module RCBO's are often this format.
Edit: Adam replied while I was making drinks
Yes John, there are some "Garo" make types that actually switch double pole - disconnect the N along with the Line conductor, just be careful if choosing them because they do both the actual DP switching an the DP but solid N types and you need to get the correct one if using them for a TT installation. They also have a consumer unit range that supports DP busbars for use with.
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The standard MCB/RCBO is too large to fit in the yellow brick, and they do not have appropriate weather proofing, the small thermal only trip does have a cover which can be used, and as far as RCD's go, there is a problem finding ones which will work with 55 volt, there seem to be some in line versions, as to if it really needs RCD protection for the extra 5 volt is debatable.
The biggest problem with on site 110 volt supplies is fire, and a path to earth is needed to get the 40 amp, so use of a RCD would help, not against shock, but from fire.
As to TN or TT it hardly matters the yellow brick is portable, so it may end up with either.
However although the danger has been identified, the problem is how can one fail a brand new device? If a safety officer bans them, OK, but as an electrician we don't really have the clout to say not to be used.
The 110 volt site rules do not apply where I work, however again talking about portable equipment, and is a tradesman buys 110 for one job, had to say you can't use it on another. Where I work water is the problem, a building leaking like a colander, and we also have marques and the like, which are lit for events, and the 110 volt festoon lighting is less likely to have problems out in the rain.
I do question LED in festoon lighting, as very little heat to dry out any water which does get in, I wonder if 110 volt is more aimed at making it so stealing bulbs is pointless.
The common situation is a long 230 volt lead feeding a brick which then feeds the lights, and one does wonder what is the point, they want the brick local to the user so they can remove the 230 volt supply, so the brick does not get left powered up, as even with no load they get quite warm, however that seems to defeat the whole point of having 110 volt.
The biggest problem with on site 110 volt supplies is fire, and a path to earth is needed to get the 40 amp, so use of a RCD would help, not against shock, but from fire.
As to TN or TT it hardly matters the yellow brick is portable, so it may end up with either.
However although the danger has been identified, the problem is how can one fail a brand new device? If a safety officer bans them, OK, but as an electrician we don't really have the clout to say not to be used.
The 110 volt site rules do not apply where I work, however again talking about portable equipment, and is a tradesman buys 110 for one job, had to say you can't use it on another. Where I work water is the problem, a building leaking like a colander, and we also have marques and the like, which are lit for events, and the 110 volt festoon lighting is less likely to have problems out in the rain.
I do question LED in festoon lighting, as very little heat to dry out any water which does get in, I wonder if 110 volt is more aimed at making it so stealing bulbs is pointless.
The common situation is a long 230 volt lead feeding a brick which then feeds the lights, and one does wonder what is the point, they want the brick local to the user so they can remove the 230 volt supply, so the brick does not get left powered up, as even with no load they get quite warm, however that seems to defeat the whole point of having 110 volt.
There is no real right position for the transformer, there are some very wrong though. obviousely the biggest volt drop issue is the lower voltage side. As an example let's say 1KW of lights are 100m from the 240V source and using 1.5mm² the volt drop would be 10 or 22.
My very first encounter with 110V was in a telephone exchange, a BT electrician working above the equipment racks had run an extension reel up, then plugged his transformer in (very heavy hammerite grey steel box and metal Reyrolle connectors in those days) and his drill into the transformer.
I asked what the grey box was and finding out immediately questioned the validity of using it that way. A some months later he proudly showed me the cables he'd made. White ribbed rubber which by then were very 'off white'.
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Over 3.5 KVA the transformers tend to have overloads on the output, and at 1 KVA to earth only 18 amp, so 1 KVA and under not a problem, it is the units between 1 and 3.5 KVA. A 16 amp unit will draw 7.65 amp at 230 volt, and has a 1.76 kVA load, so there is really no need for a yellow brick to be over 2 kVA. OK that's still 36 amp at 55 volt, but that is better than 54 amp which equates to 13 amp at 230 volt.
I think you are being a little hopeful
I've used a fair few 5KVA of this style
and don't recall anything other than a thermal primary trip.
I'm not sure I follow you. Ideally a true short circuit will be ∞A realistically the I²R losses in the whole system will reduce this to a relatively low value.
The 1.5KVA I repaired had a 6A thermal trip or ~1380VA, reflecting that into the 55V secondary ~25A. However that is effectively a 'working current' not fault.
I purchased a 3.3KVA due to finding the fluo task lighting would dim significantly, sometimes extinguish when starting power tools when using a 1.5KVA.
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