Working out Kw usage

[OllyO]

Not sure if this is the right place for this topic but here goes.

I am moving into a new workshop and I have just had a call from the landlord to say that the power company that is installing the meter want to know what my Kw usage will be. I presume this is so they can install the correct size cables etc? Don't know much about this kind of thing.
I got to be honest, I have no idea how much power I use. Does anyone out there have an answer for the power folk? or do I literally have to calculate the usuage of each of my machines? If so I need to allow for the fact I'll be buying more and more gear over the next x amount of time.
The space has 3 phase and 230v if that changes anything?

 

[skotl]

It's a very tricky question to answer without some actual measurement.

You certainly don't add up all of your devices, which would give a theoretical load if everything was running at full tilt at the same time, cos that's never going to happen.
You can't even really add up all the devices that you think you'll be running at the same time as the concept of diversity applies. A simple example of diversity is your double oven and two electric hobs being switched on - firstly, none of them will likely be turned up to the max but also each one is constantly being turned off and on to maintain the temperature. So diversity suggests that you don't add the max ratings of your oven and hobs together.

In a workshop, the suggestion is that (if there's just one of you) then you can't be running the lathe, chopsaw and welder at the same time.

I'd tot up a few hundred watts for lighting, the radio, etc. then add heating for the winter (3Kw?) and perhaps 1.5 to 2.0 x the max sustained power requirement of your heaviest (electrically-speaking) bit of kit.

Or, perhaps more simply, 20A for the ring sockets (say 5Kw) and 30A for a welder type circuit (7.5Kw) so circa 12-13Kw? Of course, I don't know what tools you have!

 

[the snooper]

Just tell them what type of business you are how many people work in the unit and what machines you have and likely to have they will get an idea of what supply you need as they will be used to decking with it

 

[Kent]

work on the bigger side as it will still do the job, that's what I did

 

[OllyO]

Cheers all, yes I'll give them a bell directly and see what they say. I've got a fairly standard set of machines at present (MMA, MIG, Lathe, grinders, polishers etc) but will be expanding in the future. I may also take someone on so there is always the possibility of multiple machines running at the same time.

 

[Justme]

Just remember they tend to charge more daily charge & higher unit rate for larger supplies.

 

[MrFluffy]

More is always good.
I have to turn my cnc mill off to use my wire edm as the inrush current as it saturates the 100v 3phase transformer that runs it (japanese machine tool) throws the breaker out otherwise. Its not really a pain, but as both machines can run automated unattended once set up, it'd be a right pain if I used them to make a living and wanted to do this.
I have 3 phase 30amp per phase in my supply. I was going to buy a din rail mount inrush limiter then I had a quote for the price of a 3phase 30amp unit...