3-phase split load design

[podz]

Please educate me. Why are you calculating your current with a power factor of .8? Your element should be pretty much purely resistive, no inductance or very very little.

Here in the states it would be (8500/2)/120 = 35.5 amps. Which would require 2 X 8awg or (I think for metric) 3.5mm wire. Thats a pretty big difference between that and 3 X 14awg or 1.5mm wire if I had your electric system.

I just use .8 for safe measure as a general rule, but you're right - I could run an even bigger element on my 16 amp circuit.

The law here regarding fixed wiring: 1.5mm for 10 amp breakers, 2.5mm for 16 amp breakers, 4mm for 20 amp breakers (although I'm running 6mm to my sub panels that are connected with 20 amp breakers). So, my 3-phase socket is wired to the panel with 5x2.5mm.

For extension cords and underground cable, you can run 16 amps on 1.5mm wires but I buy 2.5mm extension cords anyway. Skinny wires start fires.

 

[lschiavo]

hot water heater

I only bother to heat cold water I thought this was a regional misnomer. Makes me feel better that it is a global phenomenon.

For geothermal heat pumps, the motor is either to be wired as 3-phase or 1-phase connected via a safety switch. A safety switch is a switch that shuts off power if it notices the wire heating up i.e. the motor is not spinning for some reason.

The motor that circulates hot water in my house for heating and showers is wired with a safety switch. And it's a real bitch because every time I shut off power to the house, that motor refuses to restart on it's own. I need to unmount it, stand it on a shelf and hit the fins with my finger to kick start them. Then I need to let it run like that for about 15 minutes before it will restart on it's own with the safety switch before I can remount it.

That does sound like a motor issue. Thermal protection should not affect the motor especially if it is external.

Not sure if the calculation is correct, but with 400v, 3-phase, power factor 0.8, an 8500 watt element should pull about 15.5 amps. So, that will clearly fit within my 16 amp circuit. I don't know if that power factor is correct or not, I just guessed it.

Assuming I heat 25 litres of water from 20c to 100c with an 8500 watt element, it should take 16.5 minutes. Not bad.

http://processheatingservices.com/water-heating-time-calculator/

I finally get it after reading the previous posts. You have a 400V wye system with 230V to neutral. Derp. Well now I know.

Be as it may, I am still able to run an 8.5kW heating element on my puny service whereas most of you are not able to do it even on your huge ass services. ;-)

A watt is a watt my friend. I have plans to build a 22kW 1 bbl brewery on my 100A 120/240V service. The family may have to sit in the house in the dark until the brew day is over Actually my brew buddy seems to have lost interest so I may just get my 50A 10 gal system going again.

Unbelievable. That's less than 50 KVA. I guess pottery isn't a common hobby over there. In the US they'll install as much as you are willing to pay for - even three phase if you want it (you don't when you see the price tag).

It is not far from a 200A 120/240V which is way oversized for just about any residence except for the one with a guy with 3 kilns trying to run a business from his garage. I wired that guy's garage BTW

Podz,
I've noticed your pics show 'surface mounted' cabling. Are any wires concealed in the walls, attics, sub flooring?

'da Kid

It seems my finely tuned wire fishing skills would be worthless in Europe. I never fished through sawdust insulation though. We are not that far removed from Finland around here but I have yet to find a wall insulated with sawdust

 

[podz]

I only bother to heat cold water I thought this was a regional misnomer. Makes me feel better that it is a global phenomenon.

Yeah, it's a funny one!

I finally get it after reading the previous posts. You have a 400V wye system with 230V to neutral. Derp. Well now I know.

Yes, I get 400 volts between phases and 230 volts between phase and neutral.

It seems my finely tuned wire fishing skills would be worthless in Europe. I never fished through sawdust insulation though. We are not that far removed from Finland around here but I have yet to find a wall insulated with sawdust

It sucks quite badly. It's not even sawdust, it's more like wood shavings from the sawmill planers. Even when using a 40cm long 30mm wood boring bit, the holes get clogged when trying to pull anything through them. I did have to pull a 5x6mm2 cable above the ceiling from the foyer to the kitchen because the room between them had a lowered ceiling and this was the only route.

Fact is, though, that most walls in european dwellings are solid concrete. Drywall is not an incredibly popular thing here and almost everybody owns a hammer drill even for the purpose of mounting pictures on the wall. And in the houses that do use drywall, they lay flexible piping first and then pull a bunch of phase / neutral / ground wires through it - always leaving the pulling string in place for future work. So, yeah, drywall fishing skills are not of much use here.

 

[podz]

I have 3-phase 400v in my garage now, with it's own 4-pole GFCI.

 

[lschiavo]

Progress! I was wondering what happened to you. Sexy looking connectors. So you can run that cable straight through concrete without a sleeve? I wanna see some brewery pics soon

 

[podz]

Progress! I was wondering what happened to you. Sexy looking connectors. So you can run that cable straight through concrete without a sleeve? I wanna see some brewery pics soon

It's not illegal, where the f... is the concrete going to go?

Brewery will be completed when 1) I win the lottery and 2) swmbo loses her attitude about helping me organise the garage! Or maybe sooner...

 

[lschiavo]

It's not illegal, where the f... is the concrete going to go?

I agree. I guess it is more the issue of exposed cable on concrete. I suppose some ******* crushed a cable against concrete and got dead somehow. Now its a rule around here

Brewery will be completed when 1) I win the lottery and 2) swmbo loses her attitude about helping me organise the garage! Or maybe sooner...

I would start buying tickets. Much better odds than a SWMBO loosing her attitude. I just got reamed a few minutes ago for no reason I can imagine. I even had dinner ready when she got home from work. Hopefully..."maybe sooner"

 

[podz]

I agree. I guess it is more the issue of exposed cable on concrete. I suppose some ******* crushed a cable against concrete and got dead somehow. Now its a rule around here

Tort does not exist in Finnish law; you can not sue an electrician or cable manufacturer because you chop a cable in half with a full-metal axe and get a shock. GFCI would trip in 30 milliseconds, anyway.

I would start buying tickets. Much better odds than a SWMBO loosing her attitude. I just got reamed a few minutes ago for no reason I can imagine. I even had dinner ready when she got home from work. Hopefully..."maybe sooner"

TIP: not a good idea to start drinking before SWMBO is able to start drinking. Jealousy of the situation and all that.