feasibility of three-phase power in mobile catering trailer

[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.