UK New electric supply connection

[wwilts]

New 46kVA electric supply to new backland dwelling (37m from footpath). Mains cable runs along the footpath at the road access.
Which option would you choose and why?

Option 1

Meter box near footpath. Own fuse and armoured cable (>30m distance) underground to new dwelling.

Option 2

Meter box 25 m from footpath. Own fuse and armoured cable (<15m distance) underground to new dwelling.

 

[Rockingit]

46kVA to a dwelling?? Are you sure you actually mean that?

 

[wwilts]

46kVA to a dwelling?? Are you sure you actually mean that?

Yes.
Two phase.
Future proofing for EV chargers.

Question: meter box near mains cable
OR
25m from mains cable (with SWA provided by DNO)

 

[Rockingit]

With respect, I think you need to take a second look at your demand calculations. Post up exactly what it is that you’re looking at building.

 

[wwilts]

With respect, I think you need to take a second look at your demand calculations. Post up exactly what it is that you’re looking at building.

One dwelling
with up to 2 EV chargers
22kW fast x 2
43-50kW rapid x 1

Charging point can be located near external meter box if needed to simplify cable to dwelling

Trying to understand pros and cons of external meter box located near mains cable OR nearer to dwelling

 

[westward10]

Yes.
Two phase.
Future proofing for EV chargers.

Question: meter box near mains cable
OR
25m from mains cable (with SWA provided by DNO)

You mean three phase?

 

[wwilts]

You mean three phase?

DNO states "dual phase supply installed into a secure waterproof cabinet provided and installed by customer"

 

[timhoward]

A simple sketch might be worth a thousand words with this one.

 

[Rockingit]

I'm assuming that you've already had the DNO quotation for the new transformer, etc etc?

 

[wwilts]

A simple sketch might be worth a thousand words with this one.

Here it is. Option 2 could have EV chargers near meter box.
From meter box to dwelling could be usual domestic supply (eg. 11 kVA)

 

[Rockingit]

In the meantime, to answer your question, you want to get the DNO intake and meter as close to the property as possible - the simple reason being that as/if/when something goes wrong it's the DNO's responsibility to fix it, not yours!! Remember - you only own from the meter onwards.

 

[Rockingit]

From your pic, I'd strongly suggest you just get the DNO to quote for a new supply to the property. And if you really DO want that much energy, I'd just ask to get a 100/3ph installed instead - may well be cheaper and will certainly be safer and easier to deal with on site.

 

[wwilts]

In the meantime, to answer your question, you want to get the DNO intake and meter as close to the property as possible - the simple reason being that as/if/when something goes wrong it's the DNO's responsibility to fix it, not yours!! Remember - you only own from the meter onwards.

Great. Understood, thanks

 

[brianmoooore]

You mean three phase?

If the DNO are talking two phase (230-0-230) then 3 phase may not be available. This has been a problem throughout most of my working area. Quite a few of my customers have two phase supplies, including myself, but I can count the number of customers I have with 3 phase supplies on the finger of my hands. Possibly just one hand.
In answer to the OPs question, definitely not option 1.

 

[telectrix]

agree with 3 phase option. you might want 3 phase equipment at some time in the future. and meter box as close to the dwelling as possible.

 

[pc1966]

I'm guess the two-phase is common in rural places when they just have twin HV cables to pull the supply off, and prefer to offer 230-0-230 at 100A rather than 230 at 200A for obvious reasons.

Usually I prefer the name "split phase" but it really is two phases as for a N-phase system each line is 360/N degrees different, and so when balance there is no neutral current.

The issue with single and 2 phase is you can't generate a rotating field or other phase sets from it, so motors need capacitors to get going and all of the sort of problem. In these days of VFD for motors it might be less of an issue, but there is still loads of industrial kit (and probably farming equipment) that assumes a 3 phase supply is present.

With 3-phase (or higher) you can use weird transformer arrangements to get any other phase arrangements you want, probably the most common has been the Scott-T to get 4-phase (as 2 * single phase at 90 deg to each other) or the ones using both star and delta windings, etc, for 6-phase supplies common for DC generation in the olden days of mercury arc rectifiers. Still probably used today, as it lowered the ripple on the DC supply (so less of a smoothing choke needed) and dropped the 3rd harmonic seen on the incoming HV side, but it has been years since I studied that sort of thing.

 

[telectrix]

agree with 3 phase option. you might want 3 phase equipment at some time in the future. and meter box as close to the dwelling as possible.

I'm guess the two-phase is common in rural places when they just have twin HV cables to pull the supply off, and prefer to offer 230-0-230 at 100A rather than 230 at 200A for obvious reasons.

Usually I prefer the name "split phase" but it really is two phases as for a N-phase system each line is 360/N degrees different, and so when balance there is no neutral current.

The issue with single and 2 phase is you can't generate a rotating field or other phase sets from it, so motors need capacitors to get going and all of the sort of problem. In these days of VFD for motors it might be less of an issue, but there is still loads of industrial kit (and probably farming equipment) that assumes a 3 phase supply is present.

With 3-phase (or higher) you can use weird transformer arrangements to get any other phase arrangements you want, probably the most common has been the Scott-T to get 4-phase (as 2 * single phase at 90 deg to each other) or the ones using both star and delta windings, etc, for 6-phase supplies common for DC generation in the olden days of mercury arc rectifiers. Still probably used today, as it lowered the ripple on the DC supply (so less of a smoothing choke needed) and dropped the 3rd harmonic seen on the incoming HV side, but it has been years since I studied that sort of thing.

think when i was at college, that part of studies clashed with a 2 week beer fest. no contest.

 

[brianmoooore]

It's commonly known as split phase around here, but technically it's two phase.

 

[plugsandsparks]

If it is 2 phase, might be worth re-visiting your EV charger options as the 22KW ones (AC) i know of are 3 phase and ditto for rapid chargers

 

[brianmoooore]

I'm guess the two-phase is common in rural places when they just have twin HV cables to pull the supply off and there is still loads of industrial kit (and probably farming equipment) that assumes a 3 phase supply present.

Tell me about it! I've spent many hours of my life trying to get suppliers to understand that I require equipment to be supplied with 480 volt single phase motors, not 440 volt motors.
It was common for them to deny such motors existed.