Vijay Posted September 2, 2017 Share Posted September 2, 2017 I've done a search but only 1 short thread came up so I assume not many have bothered, but is there good reason to get a 3 phase supply installed? There's not much in it for the initial connection, but what downfalls are there for day to day usage? My DNO has said I can meter it art single phase or downgrade at a later time, but how would the effect the actual supply costs and availability? Any advice would be appreciated Vijay Link to comment Share on other sites More sharing options...
ProDave Posted September 2, 2017 Share Posted September 2, 2017 Put simply, a 3 phase supply will give you 3 times the capacity, and allow you to use 3 phase machine (e.g a lathe for instance) Unless you expect a particularly large demand, or you own a 3 phase lathe, then there is probably not much point? I believe you pay a slightly higher daily standing charge for 3 phase, but the unit price should be the same. 3 phase may or may not be available where you are. e.g. were I am we are on a single phase overhead supply. It's almost a mile of cable to where it joins the 3 phase network, so the cost of getting 3 phase here would be astronomical. However you may be lucky and there might be a 3 phase supply available right next door. Link to comment Share on other sites More sharing options...
A_L Posted September 2, 2017 Share Posted September 2, 2017 It means you can get 3x as much renewables as well, you will be able to export at least 3.68kW per phase. Link to comment Share on other sites More sharing options...
Vijay Posted September 2, 2017 Author Share Posted September 2, 2017 I don't expect a large demand or own any 3 phase equipment, but as with everything, I'm trying to future proof. I was quoted approx. an extra £150 to get 3 phase installed, so I'm thinking it might be worth it cos then it's there if I ever want it? I don't think I'll have enough roof space in the right direction to extend the renewables but I wasn't planning to export anyway due to having to have the accredited fitting charges Link to comment Share on other sites More sharing options...
Alexphd1 Posted September 2, 2017 Share Posted September 2, 2017 For the renewable argument it is possible to get more than 3.68kw on a single phase but this has to applied for to your DNO. It may become a advantage for charging a electric car but other people on here are more clued up on this. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted September 2, 2017 Share Posted September 2, 2017 We have 6.25kWp of PV on a single phase supply OK, and I have two electric car chargers on the same supply (one 7 kW one, one 3.5 kW one that's upgradeable to 7 kW). No problem with the DNO at all, although I did need to get permission from the DNO for the G59 PV connection. No cost associated with this at the time, just a form to fill in. The DNO had already verbally confirmed that they were OK with up to 10 kWp generation on a single phase if we wanted it. Link to comment Share on other sites More sharing options...
AliG Posted September 2, 2017 Share Posted September 2, 2017 I got a three phase supply, as electric cars become the norm as well as induction hobs then it becomes increasingly possible to max out the capacity of a single phase supply. I am just about to order up my Tesla charger which can connect pretty much to any supply that you have. As far as I can see there was little extra cost. The CU was more expensive, but it made no other difference to internal wiring. Link to comment Share on other sites More sharing options...
dpmiller Posted September 2, 2017 Share Posted September 2, 2017 £150 extra? break their arm for it. 1 Link to comment Share on other sites More sharing options...
Ferdinand Posted September 3, 2017 Share Posted September 3, 2017 (edited) 9 hours ago, JSHarris said: We have 6.25kWp of PV on a single phase supply OK, and I have two electric car chargers on the same supply (one 7 kW one, one 3.5 kW one that's upgradeable to 7 kW). No problem with the DNO at all, although I did need to get permission from the DNO for the G59 PV connection. No cost associated with this at the time, just a form to fill in. The DNO had already verbally confirmed that they were OK with up to 10 kWp generation on a single phase if we wanted it. Jeremy is right. The 3.68 (or whatever) limitation on PV is on "right to connect". We have 9.98kwp of solar pv on a single phase, and had to ask the DNO. And on of the faster of the normal car chargers, that was £100 extra when they were installing the normal ones free. Think it is a 7kw device. Ferdinand Edited September 3, 2017 by Ferdinand Link to comment Share on other sites More sharing options...
Vijay Posted September 3, 2017 Author Share Posted September 3, 2017 The only disadvantage I can possibly see is if I get any 3 phase stuff, I have to keep the supply to use it - unless the 3 phase to single phase converters are any good? Link to comment Share on other sites More sharing options...
Jeremy Harris Posted September 3, 2017 Share Posted September 3, 2017 4 minutes ago, Vijay said: The only disadvantage I can possibly see is if I get any 3 phase stuff, I have to keep the supply to use it - unless the 3 phase to single phase converters are any good? I had an ex-commercial garage 3 phase compressor for a while. I ran it on a second-hand three phase converter box (one of the ones that just used big chokes and capacitors) and it worked fine. That was around 35 years ago. Modern 3 phase converters are far smaller and probably far more reliable, too. My small milling machine uses what amounts to a 3 phase motor, a brushless DC motor with a speed control drive that is just a variable frequency 3 phase supply. My lathe is about to have it's motor changed for a similar set up, just because it's nice to have constantly variable speed with maximum torque at any speed. Link to comment Share on other sites More sharing options...
ProDave Posted September 3, 2017 Share Posted September 3, 2017 I actually run my lathe on a 3 phase variable speed drive (even though it is a single phase motor) so that is probably the way to go for a small 2 phase machine at home. The VSD lets me change speed without faffing about changing belts and pulleys Link to comment Share on other sites More sharing options...
Vijay Posted September 3, 2017 Author Share Posted September 3, 2017 Looking on Ebay, they do digital ones but prices vary from £300 to over a thousand. I'm looking at a 3 phase steam pressure washer now and don't want to get it if it can't be used............... Link to comment Share on other sites More sharing options...
dpmiller Posted September 3, 2017 Share Posted September 3, 2017 how many HP/kW/A is the pump motor? And is the heater electric or diesel? Link to comment Share on other sites More sharing options...
ProDave Posted September 3, 2017 Share Posted September 3, 2017 I would want to know more about the pressure washer. My bet is it could be rewired so the heaters are all on single phase (probably not possible if they are wired delta) leaving only the motor needing 3 phase, which a small inverter would deal with. Link to comment Share on other sites More sharing options...
Vijay Posted September 3, 2017 Author Share Posted September 3, 2017 Waiting on the model number and power rating. I believe the heater might be diesel Link to comment Share on other sites More sharing options...
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