Upgrade to 3 phase

[JohnW2]

Going back to the original question, what is the budget to get a 3 phase supply (or even just to get a second supply at the same phase)? The reason I ask is that it might be cheaper (and greener) to use that budget to buy the LED stage ligts and problem somved a lot cheaper and quicker.

Indeed so. However, IF there are already three phases going to the cutout, then the cost of moving to a 3-phase supply could be 'minimal'. On the other hand, if all 3 phases are not going to the cutout then the cost of getting a 3-phase supply could well be ££££ - and, as you imply might be similar to the cost of changing to LEDs.

Kind Regards, John

 

[Steven Prentice]

I'd agree with that John. My concern for the costs are how the church uis configured inside, rather than the DNOs charges. For eample the stage lighting might all be plugged into a single ring main and could be taking pretty much all of the peak 100A load. This circuit might need to be split betwen phases and so the work becomes adding consumer units plus adding 2 or 3 new socket rings circuits. Then once you are dong that much work would a full rewire - though costly - become more viable if you have to do half the work anyway? Another concern I would have is having 2 different phases in the same room, I would prefer them more seperated (people can get odd ideas sometimes, so best to remove some of the potential dangers).

So yes, I would check out the costs of reducing the load

 

[JohnW2]

I'd agree with that John. My concern for the costs are how the church uis configured inside, rather than the DNOs charges. For eample the stage lighting might all be plugged into a single ring main and could be taking pretty much all of the peak 100A load.

I very much doubt that a single circuit will be supplying anything like 100A worth of load!

This circuit might need to be split between phases ...

There would obviously be no point in moving to a 3-phase supply if one was not going to spread the load across the phases.

... Another concern I would have is having 2 different phases in the same room, I would prefer them more seperated (people can get odd ideas sometimes, so best to remove some of the potential dangers).

One quite often hears this, but I'm not too sure what the concern is (unless it relates to potential hazards to idiotic electricians in the future) - a 'mere' 230/240 is more than capable of killing in the face of badly designed, constructed or maintained installations, or stupid people.

Kind Regards, John

 

[AdrianUK]

Unless the thespians are very AmDram, the lights aren't going to be plugged into 13A sockets. Theatre style dimmers tend to exist in multiples of 6 x 10A (or sometimes 5A) channels. If portable these are often terminated in 63A single or 32A three phase ceeforms. It is possible to run a six pack from 13A socket if the lanterns are 500W each, but most are 650W or 1200W a piece so a fully populated dimmer isn't really practical. Anything but the smallest production is going to require around 24 channels or more channels if lighting several different scenes is required.

Using the above, its easy to see that sensible way forward might be to provide 4 x 32A 3 phase ceeforms backstage.

 

[SUNRAY]

I'd agree with that John. My concern for the costs are how the church uis configured inside, rather than the DNOs charges. For eample the stage lighting might all be plugged into a single ring main and could be taking pretty much all of the peak 100A load. This circuit might need to be split betwen phases and so the work becomes adding consumer units plus adding 2 or 3 new socket rings circuits. Then once you are dong that much work would a full rewire - though costly - become more viable if you have to do half the work anyway? Another concern I would have is having 2 different phases in the same room, I would prefer them more seperated (people can get odd ideas sometimes, so best to remove some of the potential dangers).

So yes, I would check out the costs of reducing the load

I totally follow your comments but in this situation they don't really apply, there are 5 CU's: 2 for kitchen/ancillaries, hall 1, hall 2, stage lights, and generally the existing circuit arrangements are fairly well designed. Other than the DNO, the expenses will only be altering tails [possibly including upgrading from 16mm²] and providing a main switch, so I anticipate <£50. The only phase clash is likely to be hall power/stage lights.

The stage lighting is currently 3x16A radials feeding 1x 13A socket so the max supply is 39A & existing available load is 7.4KW [plus a few extras brought in if needed]. I know it's easy to jump on the stage lighting band wagon but they are only used about 3 times a year and very likely account for less than 100KWH [£15 ish] which is tiny in the overall consumption.

As someone else also suggested the assumption is the biggest single instantaneous load is most likely to be the hand dryers.
A lot of cooking takes place with multiple, >12, slow cookers in addition to the regular kitchen on a regular basis and I think kettles/urns are used for a majority of bookings.

 

[Steven Prentice]

John, I don't know the installation so got to assume the worst case.

However it might be that there are several rings all split and able to transfer straight into a 3 phase bioard as they are (say east church, west chirch, stage, balcony, basement, kitchen and so on). It mght be that there are only 1 or 2 circuits and so these need to be split - one has little cost one has larger cost. I don't know.

It is worth noting this and the potntial costs so that the OP can make a better judgement nd look to possible cheaper alternatives


Multiple phases in 1 location. Especially when to the domestic user all the sockets will look the same. Yes a bit tro save us from the idiots, but also from equipment failures where 2 adjcent pieces of equipment might develp a 415V fault between them




Adrrian- in this case the group only have 1 phase available and I am making an assumption tha these will be13A sockets because of this

 

[SUNRAY]

Unless the thespians are very AmDram, the lights aren't going to be plugged into 13A sockets. Theatre style dimmers tend to exist in multiples of 6 x 10A (or sometimes 5A) channels. If portable these are often terminated in 63A single or 32A three phase ceeforms. It is possible to run a six pack from 13A socket if the lanterns are 500W each, but most are 650W or 1200W a piece so a fully populated dimmer isn't really practical. Anything but the smallest production is going to require around 24 channels or more channels if lighting several different scenes is required.

Using the above, its easy to see that sensible way forward might be to provide 4 x 32A 3 phase ceeforms backstage.

Oh yes these ARE very AmDram and yes all the stage lighting is done with 13A plugs from the dimmer packs.

When I was first involved I asked for a couple of 32A 1ph sockets which was refused

 

[JohnW2]

John, I don't know the installation so got to assume the worst case. ... I don't know.

No need to assume any more, since we've been told.

It is worth noting this and the potntial costs so that the OP can make a better judgement nd look to possible cheaper alternatives

I would be very surprised if he had not already considered the various options.

Multiple phases in 1 location. Especially when to the domestic user all the sockets will look the same. Yes a bit tro save us from the idiots, but also from equipment failures where 2 adjcent pieces of equipment might develp a 415V fault between them

As I said, I think this perceived risk is greatly overplayed. I am a 'domestic user' who has a 3-phase supply and, although the phases never get very near to one another, it would not particularly concern me if they did.

I suppose what worries me when people raise this concern is that it seems to suggest that they are underestimating the danger of 230/240V - in other words, by expressing concern about "equipment failures where 2 adjacent pieces of equipment might develop a 415V fault between them", they seem to be implying that they are not equally concerned about "equipment failures where 2 adjacent pieces of equipment might develop a 240V fault between them". 230/240V can kill just as well as can 400/415V.

Kind Regards, John

 

[SUNRAY]

Personally I think people are scared of the higher voltage, yes it hurts a lot more and yes it tends to do more damage but realistically the number of faults/failures tends to be low. I have regularly installed sound systems with the 3 phases alternating up the racks of amplifiers and worked in 3ph control panels without giving it a second thought.

Is it still in the regs to label adjacent sockets/switches if they're on different phases?

 

[ban-all-sheds]

Another concern I would have is having 2 different phases in the same room, I would prefer them more seperated (people can get odd ideas sometimes, so best to remove some of the potential dangers).

Why? What odd ideas might they have?

Multiple phases in 1 location. Especially when to the domestic user all the sockets will look the same.

An odd idea, maybe, like opening up two sockets without turning off the power and contriving to make contact with both line conductors at the same time?

Yes a bit tro save us from the idiots, but also from equipment failures where 2 adjcent pieces of equipment might develp a 415V fault between them

And how might that happen?

Quite honestly, what with all this and your opining on isolators I think you are the one with odd ideas.

Adrrian- in this case the group only have 1 phase available and I am making an assumption tha these will be13A sockets because of this

Err...

Why?

 

[John D v2.0]

Is it still in the regs to label adjacent sockets/switches if they're on different phases?

As far as I know you can have two phases in the same accessory with no special issue. Eg two gang switch

 

[JohnW2]

Personally I think people are scared of the higher voltage, yes it hurts a lot more and yes it tends to do more damage but realistically the number of faults/failures tends to be low. I have regularly installed sound systems with the 3 phases alternating up the racks of amplifiers and worked in 3ph control panels without giving it a second thought.

Quite so.

Is it still in the regs to label adjacent sockets/switches if they're on different phases?

It seems not, and I'm really not sure what one was meant to do about it even when it was required!

Having said that, the one possible hazard (to people working on the installation), and nothing to do with voltages (or even directly to do with phases), is that people might (wrongly and dangerously) 'assume' that if one socket has been isolated, that the same would be true of an adjacent one. However, they don't have to be on different phases to present that theoretical hazard - merely being on different circuits on the same phase presents the same issue.

I would certainly try not to have 'adjacent' sockets on different circuits/phases but if I did, I would be inclined to do some sort of labelling, even though not required by regs.

Kind Regards, John

 

[JohnW2]

As far as I know you can have two phases in the same accessory with no special issue. Eg two gang switch

That appears to be the case (with no 'labelling' required). Indeed, it must be very common with 2-gang 2-way hall/landing light switches.

As I've just written, I don't see the issue as being the pds involved (what precautions would one take if one knew that a pd pf 400V was present that one wouldn't take for 230V?) but, rather, that it will be necessary to isolate two final circuits to make it safe to work inside the accessory/whatever - and the same hazard exists if there are two circuits on the same phase. Although the regs require warning labels if there are 'alternative supplies' (all of which need to be isolated for safe working), I'm aware of no labelling requirement when two or more circuits (whether on the same phase or not) are present within an accessory/enclosure/whatever.

In my house, other than in the up-front TPN isolator, I think that the only places where two different phases exist in the same enclosure are where I have 'phase failure relays' (to provide a little light from a different phase in the event of a single-phase failure). In those cases, I have used warning labels, to remind myself (or others) of the need for 'dual isolation' for safe working. Cross-floor (which roughly equates to 'cross-phase') CH controls etc. are done at ELV, with relays, to avoid this problem/hazard.

Kind Regards, John

 

[ban-all-sheds]

I would certainly try not to have 'adjacent' sockets on different circuits/phases but if I did, I would be inclined to do some sort of labelling, even though not required by regs.

 

[AdrianUK]

There are alot of 'old wives tales' and other myths passed down through the generations about the 'dangers' of kit powered from different phases. Not least within the BBC of all places. In my 'former life' of power generation & distribution in the entertainment business I've had several heated discussions with quite senior Engineers about powering OB trucks. Historically all TV OB gensets where single phase. OB trucks were configured to take in multiple feeds (eg. technical, Hotel & Air con) which it was clearly stipulated must all be on the same phase. Indeed the input panels often had neons wired between the phase pins of the (often 63 or 125A) ceeforms to detect if the supply was truely single phase or two phases from a 3 phase supply.

When questioned about this the Engineers would often get very defensive insisting that such a power scheme would lead to 415V on the interconneting cables of equipment & its ultimate destruction. Even after explaining that such a scenario would require at least a double or even triple failure combined with a bad earth they still insisted that the supply be true single phase. Even powering different OB trucks from different phases was frowned upon (same argument... the interconnecting cables between the trucks would join together two pieces of equipment that had 415V between them). Even after explaining that for that to be so the interconnecting cables would have to be at phase potential above earth ... ie. the equipment had already catastrophically failed.