feasibility of three-phase power in mobile catering trailer

[hie27]

Hi all.
First, I have to admit that i have no experience and very little knowledge in electrics and I'm therefore looking for some general practical advice. I am wanting to start my own mobile catering business but i am still in the planning stage. I want to know if three-phase power is really a viable option for starting a business that is relatively small-scale at least at the start. At the moment i have a blank canvas trailer and all of the circuitry and appliances still need to be inserted. The reason why I am even considering three-phase power is that there are some really great mini-industrial ovens that can reach 500c that you just cannot get one-phase. The only other option to hit those sorts of temperatures is woodfire ovens and they require some skill and continuous management. I am really attracted to the idea of having a small but high output oven. The oven in question is rated at 32a 4.5kw. Apart from that i would need a fridge and topping table, which would be one phase. Is 3 phase circuitry significantly more expensive than one-phase? And is integrating the other one-phase appliances into a three-phase system complex?

 

[telectrix]

4.5kW is not 32A, it's 19A single phase.

 

[Strima]

3 phase is not a problem. However what sort of hook ups are you looking at using?

3 phase isn't always available on some pitches or will you be using your own generator?

 

[hie27]

Hi, sorry perhaps i got the kw wrong. I will double check. The oven is definitely three phase as it has got the red 5 pin. I will check again thanks. And, yes, the idea was to use my own generator, although size i imagine it would be quite sizable.

 

[hie27]

Kw says 4.5 / 4.9

 

[gnuuser]

3 phase power will be more efficient to use even if it means more conductors for your mobile system, if your generator is sufficient for the task. as others have said if you were relying on external power you may have some problems with connector issues.
but i must caution you to have a good spark set this up for you. also you should check into any regs concerning an installation such as this as there may be special permits needed.

 

[hie27]

I have to admit i have no idea on hookups. Where can i get myself better informed on this topic? Thanks for the replies thus far, I did initially think this idea might be too ambitious but the consensus seems to be that it is possible, but caution is needed.

 

[Deleted member 105166]

This takes you into BS7909 territory, where it would be deemed a temporary electrical system. Demand in excess of 6kVA is deemed "large/complex" and requires a senior person responsible.

 

[Deleted member 105166]

I have to admit i have no idea on hookups. Where can i get myself better informed on this topic?

Google is your friend here, 22 million results

 

[Ned Gibbons]

What sort of events are you planning to attend. If you have events in mind I would be asking them how they feel about either providing a 3 phase hook up or letting you use a genny.

Even if they are it is likely to have an impact on where you can be located on site and may mean you often get less then ideal pitches.

I've done power in quite a few outdoor events. 3p for a trader is not something I've never been asked for.

 

[gazdkw82]

I've been involved in helping set up mobile catering outlets. I don't think I've seen a three phase one yet. All the ones I've seen have been single phase supplies for ovens/grills and fryers.

On the other side of things, I don't even think most places that host these events will have a 3 phase outlet for you to use

 

[hie27]

Thanks for all of your replies again. Its definitely food for thought. The question of the acceptability of a generator is definitely a valid point. However I don't have any plans to operate at public events. I plan to focus locally rather than live life on the road. There are no artisan pizza caterers between where I live and at least 25 mile so I plan to focus here first. I have asked a few pub land lords on the main roads on private roads and they were keen. Also, the local council did not object to a generator being used outside of an industrial site if precautions are made. With the sort of food i plan on making i will be looking more at privatr events. The limit on electrical output with further regulations on the topic of temporary electrical systems is a bit worrying. However, it might still be possible to get around this as i am aware of the hygiene regulations. I could drop the fridge and make table and operate for 4 hours with bags of ice and portable handwash if needed. In fact, all I'd need is a light and the oven and I could do it. Its not ideal but it could atleast be a start working part time while I figure how to fully comply. I realise that some of you might find my approach odd but you simply cant make a proper pizza with gas or 1 phase, I know because I've been doing it for years and the temperatures are too low.

 

[hie27]

So the big issue so far is the possibility of temporary electrical system status. Has anyone else got any other considerations? Also what is the relationship between kW and kva?

 

[davesparks]

So the big issue so far is the possibility of temporary electrical system status. Has anyone else got any other considerations? Also what is the relationship between kW and kva?

What do you mean by the possibility of temporary electrical system status?
This is going to be temporary electrical system whatever you do.

All of the pizza ovens which turn up at the events I work on are wood fired. The only power they need is a 16A SP for a few lights and suchlike

 

[hie27]

Hi Dave, are you suggesting that the oven on its own exceeds the limit or is there other points to the rule?

 

[davesparks]

Hi Dave, are you suggesting that the oven on its own exceeds the limit or is there other points to the rule?

It’s an electrical system which is not permanent, therefore it is temporary.

What limit are you referring to?

 

[Deleted member 105166]

So the big issue so far is the possibility of temporary electrical system status.

As Dave indicates above, any size of power source to which you hook up will constitute a temporary electrical system, however BS7909 treats systems up to 6kVA as "small/simple" with the main difference being the level of testing and therefore competence required. Essentially, many end users will be able to demonstrate sufficient and suitable competence to manage a small/simple event and testing the RCD.

Above 6kVA, the testing required by BS7909 is more complex and outside the remit of most end users. A good understanding of BS7671 and an MFT are required to carry out the testing, which is why events have a dedicated person doing the power, so you can simply say "give me 32A" and then concentrate on cooking!

Also what is the relationship between kW and kva?

Power factor - well documented on the web, but in simplest terms when dealing with a generator, multiply the kVA by 0.8 and you'll get the kW (the latter being real power available to do work)

 

[hie27]

Sorry Dave if I was not specific enough. I was simply asking whether I would be exposed to the higher level of regulation with just the oven. Most trailers have at least a few basic electrics and seem to manage without much scrutiny outside PAT. It looks like I may have to reconsider the idea on the basis of what's being said. Out of interest how are these regulations actually enforced? Before buying my empty trailer I looked at several used and one Lady had a gigantic generator running a multitude of electrics. She didn't mention any of these regulations and was trading from a side road quietly. Finally on the topic of woodfire, it just doesn't appeal to me they can be expensive to run and need management. Furthermore local authorities are already banning woodstoves. Who knows how long they will last with the green lobby.

 

[Strima]

Sorry Dave if I was not specific enough. I was simply asking whether I would be exposed to the higher level of regulation with just the oven. Most trailers have at least a few basic electrics and seem to manage without much scrutiny outside PAT. It looks like I may have to reconsider the idea on the basis of what's being said. Out of interest how are these regulations actually enforced? Before buying my empty trailer I looked at several used and one Lady had a gigantic generator running a multitude of electrics. She didn't mention any of these regulations and was trading from a side road quietly. Finally on the topic of woodfire, it just doesn't appeal to me they can be expensive to run and need management. Furthermore local authorities are already banning woodstoves. Who knows how long they will last with the green lobby.

A trailer installation will come under section 7 of BS7671 and will need to comply with that. And as Dave has pointed out BS7909 also comes into effect as it's classed as a temporary supply.

Dave also mentioned a lot of people use wood fired ovens, this means they only have a very small power requirement for lighting and fridges etc and compliance with BS7909 is a lot easier.

I can understand your reasoning for using an electric oven due to it's simplicity for set up, cleaning etc however gas and wood fired would be much easier from a compliance view.

Plus food prepared in a wood oven tastes much better, unless your using bitumen soaked telegraph poles as one person I knew did...

 

[davesparks]

As Dave indicates above, any size of power source to which you hook up will constitute a temporary electrical system, however BS7909 treats systems up to 6kVA as "small/simple" with the main difference being the level of testing and therefore competence required. Essentially, many end users will be able to demonstrate sufficient and suitable competence to manage a small/simple event and testing the RCD.

Above 6kVA, the testing required by BS7909 is more complex and outside the remit of most end users. A good understanding of BS7671 and an MFT are required to carry out the testing, which is why events have a dedicated person doing the power, so you can simply say "give me 32A" and then concentrate on cooking!

6kVA is suggested as a typical size for a small/simple system, not a fixed limit. I see no reason why this should not be considered a simple system if it is a single mobile unit receiving a single feed from a dedicated generator.
Also 4.5.1 if BS7909 should be applicable in this situation this simplifying inspection and test procedures.

However all this is only relevant if it falls within the scope of BS7909, which based on the OP’s earlier comments it doesn’t appear to do.

 

[davesparks]

A trailer installation will come under section 7 of BS7671 and will need to comply with that. And as Dave has pointed out BS7909 also comes into effect as it's classed as a temporary supply.

It wasn’t me this time guv, I’m not sure it does come under bs7909 yet based on what the OP has said so far.

Definitely section 7 though.

 

[norcal]

Have you considered a gas fueled appliance?

 

[hie27]

I've never seen gas ones that can hit the temperatures needed. There are some good hybrid ones available but I'm not sure what environmental health would say about their indoor use. I'm reading around and informing myself on BS7671 at the moment.

 

[Deleted member 105166]

With the sort of food i plan on making i will be looking more at privatr events.

Dave, I understand 4.5.1 is relevant here and that will indeed help the OP in simplifying his inspection and testing, but I am struggling to understand how the OP's scenario could be outside the remit of BS7909 altogether, please can you explain this?

Digressing slightly, 6.2.1 could also come into play - a probable situation if the OP is going to attend private events where another generator will be powering the marquee, toilets & entertainment.
If a caterer advises they don't need any power, most power providers will assume they are bringing gas. When said caterer then rocks up on the day with their own genny, and plonks it close to the set already up & running, this will likely impact on the existing 7909 details of supply signed off, as the METs of both sets may need to be connected.

 

[Resu]

This oven has a max temp of 300c and is 13A.

 

[hie27]

This oven has a max temp of 300c and is 13A.

You need an oven of at least 400c to make real benefit of the finer grade flours. Another practical problem is the lower the heat the slower the cooking time. So you'd have to stack a few of them to get anywhere near the output. It might be great for something like New York style though. But surely, using several of these at once would leave me with the same regulation problem regardless of phase?

 

[Deleted member 105166]

But surely, using several of these at once would leave me with the same regulation problem regardless of phase?

Yes, any/all relevant regulations in BS7671 and BS7909 apply irrespective of whether you are generating single or three phase power. Generally, the smaller sets, up to around 10kVA (will give you 34A) are single phase and above that three phase, the latter being a more efficient way of generating larger amounts of power.

 

[hie27]

In your experienced opinion, is a 3 phase more expensive to install the circuitry into a facility than a 1 phase? (but disregarding the probable need for a larger generator and greater running costs associated with more power ect)

 

[hie27]

I have another newbie question. When i looked at the oven's red 5 pin showing the electrical information, the voltage says 240/415. 415 is surely 3 phase, why then would it show 240v as well which is one phase?

 

[Deleted member 105166]

When i looked at the oven's red 5 pin showing the electrical information, the voltage says 240/415. 415 is surely 3 phase, why then would it show 240v as well which is one phase?

Phase to Phase is 400/415
Any Phase to Neutral is 230/240

In your experienced opinion, is a 3 phase more expensive to install the circuitry into a facility than a 1 phase?

It will be more expensive, but not always vastly so. Each install is different and you're in the hands of the DNO. If three phase is available very close by, you may be pleasantly surprised. Ask your DNO for a quote.

 

[davesparks]

Dave, I understand 4.5.1 is relevant here and that will indeed help the OP in simplifying his inspection and testing, but I am struggling to understand how the OP's scenario could be outside the remit of BS7909 altogether, please can you explain this?

Digressing slightly, 6.2.1 could also come into play - a probable situation if the OP is going to attend private events where another generator will be powering the marquee, toilets & entertainment.
If a caterer advises they don't need any power, most power providers will assume they are bringing gas. When said caterer then rocks up on the day with their own genny, and plonks it close to the set already up & running, this will likely impact on the existing 7909 details of supply signed off, as the METs of both sets may need to be connected.

The OP has mentioned that he is intending to set up shop outside pubs etc, this isn’t events related or related to the entertainment industry as far as I can see.
This is more closely related to street trading and kebab vans at the side of the road.

If the major use of the trailer is outside of the remit of 7909, and when it does stray in to that territory it is powered by the event electricians then I don’t see the issue.

Everyone working in event power knows that catering never know what power to order and expects a request for no power or just a 13A to be far, far more.
Much like we all know to use the old tatty kit to power the fun fair/inflatable attractions because they are going to nick some of it.

 

[hie27]

OK, so an update. I have emailed several trailer builders with the idea and some of the concerns raised here. The trailer still needs a basic kitchen fitted so I have started with the trailer guys first. I had one reply from a chap near Manchester. He said that due to safety and regulations they only put 6kw on each line anyway. He said last month he had one customer that had to have 3 separate lines in they had so many appliances. He suggested a separate line for the 3 phase oven and another 1 one for a few plugs. Basically, he said, it would be just a case of plugging each hookup to a generator that is compatible both 1 and 3 phase instead of messing around with 1 line. He said not to worry about wiring regulations and that he can get the CE certificates.

So far, does this sound like someone who knows what they are really doing? Or should I get the kitchen fitted and seek professional electrician who had dealt with 3 phase.

 

[Strima]

He said not to worry about wiring regulations and that he can get the CE certificates.

That comment has given me Forest Whitaker eye...

He should take a look as Section 7 of BS7671 as this covers wiring of transportable units etc.

 

[Deleted member 105166]

He suggested a separate line for the 3 phase oven and another 1 one for a few plugs. Basically, he said, it would be just a case of plugging each hookup to a generator that is compatible both 1 and 3 phase instead of messing around with 1 line.

The issue with that on a smaller three phase generator, is you will end up with poor load balancing. The three phase oven will draw equally across the three phases whilst the 32/1 hookup for everything else will draw all its load from the phase you choose to put it on, but with nothing else on the other two phases. Not a dealbreaker on a bigger genny, but certainly less than ideal on say a 20kVA set.

He said not to worry about wiring regulations...

That should be ringing loud alarm bells!

 

[davesparks]

Basically, he said, it would be just a case of plugging each hookup to a generator that is compatible both 1 and 3 phase instead of messing around with 1 line. He said not to worry about wiring regulations and that he can get the CE certificates.

Yeah don’t worry about wiring regulations, they only exist to prevent fires or people receiving fatal electric shocks, nothing important.

Setting up multiple small generators in one location sounds like a very tiresome, noisy, slightly dangerous affair which could be a nightmare to safely manage fuel for.

 

[Adam W]

I'm no expert on generators but from what I can make out a generator of this size will need earthing - far from just being a case of finding the best location for trade and turning on the pizza oven, every time you want to trade you'd need to find a suitable place to bang a rod in the ground, then obviously test it, before you can switch anything on, then presumably you'd need to pull the rod back out before you leave.

What I am more familiar with is the kind of questions put to this forum - in most instances it's best to go with the solution everyone else manages with.
This seems to be a case of supplying power to a wood-fired pizza van. I know you've said several times that you don't want to go down the wood-fired route, but that's how the public know the mobile pizza van - they'll be expecting an artisan street food wood-fired pizza. In many cases they'll instinctively ask for a wood-fired pizza, or refer to it as such, to which you'll have to tell them your pizzas aren't wood-fired but use the same kind of oven as the local kebab and chicken shop which also does pizzas, then see if they still like the idea.
Possibly even more important than the food is the theatre of street food - the quirky truck, the rustic signage, words like "fresh, artisan, local, hand-made, (again) wood-fired, the rustic whaft of wood smoke as opposed to the diesel fumes and clatter of a generator.

I'm not saying you can't start up a pizza van using an electric oven, just that it seems to be going against the grain.