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.