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3-phase


Tom

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Hi all - we're in the process of buying some barns to convert, there is a 3-phase supply apparently but not domestic mains. Can the 3-phase be converted or will it need to have a new supply run to the site? Any advice gratefully received! 

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Hi. 

Theyll probavly give each barn its own phase TBH but it depends on the capacity and current location of the supply. Sounds like you'll need the supply cut back and a 3-way split underground with 3x new single phase feeds rising in each 'new' dwelling. 

Others will add to this shortly. 

 

Don't forget to mention PV and ASHP ( if applicable ) when you contact the DNO for the works. 

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You might pay a slightly higher standing charge for 3 phase. But it certainly does no harm to have it.

 

If you have solar PV, them make sure your house connects to the same phase as the solar PV (otherwise you won't be able to self use what you generate and it will all get exported)

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10 minutes ago, Nickfromwales said:

No problems then. Is the head currently where you'll want it to stay ?

Lordy, don't know, really early stages with the purchase tbh. As long as we can use the supply that's there (in whatever way) then that sounds considerably cheaper than laying a new supply.

 

11 minutes ago, ProDave said:

You might pay a slightly higher standing charge for 3 phase. But it certainly does no harm to have it.

 

If you have solar PV, them make sure your house connects to the same phase as the solar PV (otherwise you won't be able to self use what you generate and it will all get exported)

Roger that :ph34r:

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On 07 March 2018 at 15:30, Tom said:

Lordy, don't know, really early stages with the purchase tbh. As long as we can use the supply that's there (in whatever way) then that sounds considerably cheaper than laying a new supply.

 

Roger that :ph34r:

You MUST use the supply that is there, as you have solar PV and the FIT contract will be tied to your MPAN (Meter Point Administration Number)  If you get a new supply it will have a different MPAN and goodbye FIT.

 

In fact I would play safe and just keep it as 3 phase. you don't want to do anything to kill off your FIT payments.

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Right, obviously I know exactly what you've all been talking about, ahem, but for the benefit of those at the back can you explain what exactly 3 phase is?!

Thanks!

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Each single phase in a 3 phase supply is typically described as L1 L2 and L3, and then you have your neutral and your earth, the earth howsoever obtained as dictated by the supply "type". Only one neutral is required to get 3 x single phase supplies. 

eg 

L1 ( red or brown ) 230v when connected between itself and neutral. 

Same for L2 and L3, so the neutral just gets split 3 ways with a Henley block ( big ass junction box ). 

 

3 phase kicks in when you have a piece of 3 phase equipment, these are typically referred to as 415 volt appliances. 

Each phase is 230 volt independently, but if you put your load across two different phases you get 415 volt, whereas any phase to neutral would only give 230 volt. 

So a true 3 phase appliance will only take power from each of the phases, and not require the neutral, other than for the control electronics sometimes. 

  

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Um...referred to now as 230 and 400V since mid '90s. 

 

Even though it may measure differently as we all know. In practice nothing has changed except us falling into line with Europe. Roll on Brexit and we can go back to proper colours where RED is live and dangerous as nature intended. :) Let's face it brown looks "cuddly"! 

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10 minutes ago, Onoff said:

Um...referred to now as 230 and 400V since mid '90s. 

 

Even though it may measure differently as we all know. In practice nothing has changed except us falling into line with Europe. Roll on Brexit and we can go back to proper colours where RED is live and dangerous as nature intended. :) Let's face it brown looks "cuddly"! 

 

I like that they changed the Blue, that nearly got me in trouble when I was wiring up the workshop, one box had both new, old and "farmer" wiring in it (3 browns and a blue)

It all got very confusing

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I have 3-phase in the new house, It supplies the Lift (required for my mother) and ASHP (soft start for both) I have also had a 3-phase 16A (22kW) run put into the garage for a future car charging point (as and when required).

I also don't have to worry about the power draw from the induction hobs (2 of for split level kitchen).

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