3 phase ovens - why?

[Steve]

What is the point in 2 or 3 phase ovens and hobs? And why sell them for the domestic market? Is it just to confuse average DIYers? Shouldnt they come with warning labels stating "warning 415v"?

I have seen 3 phase commercial ovens. Why 3 phase? Why not wire them to a 32/40A MCB on one phase? It would certainly be easier to wire.

Do 3 phase 250A (each phase) supplies exist? I overheard an electrician at a shop i was at which is having a refit, saying something about a 250 something or other! Its a big shop with a big plant unit with loads of compressors for fridges and freezers and 3 big coldrooms, loads of lights, electric fan heaters, a couple of 3 phase ovens, possibly air conditioning in the near future, would this warrant such a supply?

 

[andy]

What is the point in 2 or 3 phase ovens and hobs? And why sell them for the domestic market? Is it just to confuse average DIYers? Shouldnt they come with warning labels stating "warning 415v"?

I have seen 3 phase commercial ovens. Why 3 phase? Why not wire them to a 32/40A MCB on one phase? It would certainly be easier to wire.

Do 3 phase 250A (each phase) supplies exist? I overheard an electrician at a shop i was at which is having a refit, saying something about a 250 something or other! Its a big shop with a big plant unit with loads of compressors for fridges and freezers and 3 big coldrooms, loads of lights, electric fan heaters, a couple of 3 phase ovens, possibly air conditioning in the near future, would this warrant such a supply?

dunno, but the last place i done some work in had a 400A each phase

 

[supersparks]

dont you know why we use 3 phase?!!!?!?!?!?!

 

[plugwash]

3 phase is used for two reasons

one is to save cable though most of this saving can also be gained by using split phase.

the other reason is because it makes motors and generators run far more smoothly.

the reason you get domestic cookers that can be wired for 3 phase is that in older houses in some parts of europe 3 phase at 20A or so per phase is common. in an install like that you just can't go putting a large cooker on one phase.

 

[Steve]

3 phase is used for two reasons

one is to save cable though most of this saving can also be gained by using split phase.

the other reason is because it makes motors and generators run far more smoothly.

the reason you get domestic cookers that can be wired for 3 phase is that in older houses in some parts of europe 3 phase at 20A or so per phase is common. in an install like that you just can't go putting a large cooker on one phase.

i knew about 3 phase for motors, i did a-level physics, i know all there is to know about phases and sine waves and motors etc (i think, im sure someone on here will spout a load of super-intelligent stuff about sine waves that i didn't know!)

just didnt see the need for 3 phase commercial ovens. I did have a look at the supply head at work today, it is 100 amps on each phase, into 2 big distribution boards via big important looking metal cabinets that are locked up.

I didnt know about the 3 phase 20a supply issue. Seems a bit awkward.

 

[mapj1]

Well its as easy for the oven maker to bring some rings to one live lug, and some to another, or have 1 big lug, and the electricity suppliers prefer a balanced load, and thinner wire can be used on each phase, so if the house has a 3 phase supply, it is sensible to share the load about.
In practice its nice, not a problem, as even if the worst happens you don't normally lose the lot at once. -In a way the UK system has the company fuse as single point of failure - could be seen as a weakness by some.