DEFENDER2.NET - View topic - Power Supply to Garden Workshop

↓ Advertise on Defender2 ↓

Home · FAQ · New Posts · My Posts · PMs · Search · Members · Map · Calendar · Profile · Donate · Register · Log In

Home > Off Topic > Power Supply to Garden Workshop

Page 2 of 3

Print this entire topic ·

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20347

This is quite an interesting thread!
After reading through what does PME actually stand for?

We have a commercial installation here, and when it comes to the underground SWA. (Steel wire armoured.) cable the power line company said it can be put in on its own.
(Can't imagine any conduit would do any harm bar added cost only add even further protection.)
But* it must be at least xx depth. (Figure eludes me.) and xx distance above use SWA live cable yellow warning tape that you bury underground above the cable. The tape is BS xxx (again I can't recall the number.) standard marked and designed just for the job.

We apparently need this year to get the Consumer Unit. (MK) changed to a metal one to meet new regs.
Inc testing already done total about £800.

Hate to think what a line in, inc meter install now costs plus whole Consumer Unit install and hook up.

Brands wise always liked MK, BG & Steinel for outdoor lighting sensors.
Not a Crabtree brand fan though..

Straying off of the OP's original question. (Hope he doesn't mind a touch OT.

)

We have overhead HV lines outside which power feeds are brought down from to houses.
There isn't any transformer in sight that close that I am aware of, as the feeds are tapped off which I would imagine two live lines and two neutrals. (Unless I'm assuming wrongly.) with the 4x lines.
How is the voltage reduced down to the 220 - 240v range when reaching the house? I can't imagine the lines up there are such low voltage as that or is there some form of voltage trickery I'm missing literally closer to Home?

I find it an interesting subject, I would imagine they are somewhere between 6 KV and 32KV, 4 lines per pole mounted vertically one above the other.
There are some further away that are 3x lines mounted on a horizontal bar, I would imagine these are higher voltage again as these sometimes have transformers mounted just below also.
All are timber poles.

The power network company have been inspecting a lot with the helicopter of recent years.
I take my hat off to the linesmen that deal with all the HV network that we all rely on so much!

$W33T $0U7H3RN $UG4R
🇬🇧🏴󠁧󠁢󠁥󠁮󠁧󠁿🏴󠁧󠁢󠁷󠁬󠁳󠁿🏴󠁧󠁢󠁳󠁣󠁴󠁿🇮🇪🇺🇸⛽️🛢️⚙️🧰💪

30th Aug 2018 11:45pm

dorsetsmith

Member Since: 30 Oct 2011
Location: South West
Posts: 4554

PME Protective multiple earthing

Last edited by dorsetsmith on 31st Aug 2018 11:22am. Edited 2 times in total

31st Aug 2018 7:15am

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 17372

2007 Defender 110 Puma 2.4 DCPU Stornoway Grey

custom90steve wrote:
This is quite an interesting thread! ...

Agree

custom90steve wrote:
We have overhead HV lines outside which power feeds are brought down from to houses.
There isn't any transformer in sight that close that I am aware of, as the feeds are tapped off which I would imagine two live lines and two neutrals. (Unless I'm assuming wrongly.) with the 4x lines.
How is the voltage reduced down to the 220 - 240v range when reaching the house? I can't imagine the lines up there are such low voltage as that or is there some form of voltage trickery I'm missing literally closer to Home?

That sounds to me more like a 415V three-phase supply. Perhaps you are getting your mains from one (or more) phases.

31st Aug 2018 7:19am

Caterham

Member Since: 06 Nov 2008
Location: Birmingham
Posts: 6298

2011 Defender 110 Puma 2.4 XS CSW Stornoway Grey

/\ as you say either it's not HV or it's 400v (415v is old school

) or there is a transformer somewhere - and it's usually fairly obvious.

31st Aug 2018 7:32am

Caterham

Member Since: 06 Nov 2008
Location: Birmingham
Posts: 6298

[quote="apt100"]

Rashers wrote:

Just to add about 30mA RCD...
Many people call the green/yellow wire "earth", but there is usually a voltage difference between it and true earth. Inside a building it doesn't usually matter. When you take it outside it can be dangerous. If you have a PME supply, and there is a broken neutral in the supply network, then the green/yellow wire (and anything metal connected to it) can be close to the full 230V supply voltage above true ground. And an RCD won't be any help at all.
Hence it is illegal to have PME supply at eg caravan parks and marinas. And usually not recommended for supplies to outdoor buildings.

Would I not be right in thinking without a neutral supply the RCD will trip ie there'll be a potential difference between the phase and neautral?
If not then a guess there's no need to worry because you'll be no worse off than 95% of people in this country and guess there's also the questions of whether your looking to carryout an install that meets current regs or looking to overcome every possible eventuality?
not trying to have a dig here but more concerned that what little knowledge I have / had as either gone or become rusty

31st Aug 2018 7:45am

dorsetsmith

Member Since: 30 Oct 2011
Location: South West
Posts: 4554

RCD

Under normal circumstances, the current flowing in the two wires is equal. When an earth leakage occurs due to a fault in the circuit or an accident with the equipment, an imbalance occurs and this is detected by the RCD, which automatically cuts off the power before injury or damage can result.

31st Aug 2018 9:32am

Caterham

Member Since: 06 Nov 2008
Location: Birmingham
Posts: 6298

/\ exactly.

an inbalance (fault) will cause the RCD to trip. an overload which is generally a different type of 'fault' will not trip an RCD but should take out a fuse or MCB.

30mA RCD for protection to life
100mA RCD for protection of property
(typically)

31st Aug 2018 9:36am

leeds

Member Since: 28 Dec 2009
Location: West Yorkshire
Posts: 8581

apt100 wrote:
.
.
.
.
.
Hence it is illegal to have PME supply at eg caravan parks and marinas. And usually not recommended for supplies to outdoor buildings.

Going OT and just to satisfy my curiosity what is correct/legal/conforms to part 17/18 way of earthing/providing electrical safety at caravan parks?

Just curious as we sometimes plug into outdoor supplies on caravan sites.

How are caravans protected electrically?

Brendan

31st Aug 2018 10:13am

Caterham

Member Since: 06 Nov 2008
Location: Birmingham
Posts: 6298

I believe you'll find it's via an RCD.

31st Aug 2018 10:16am

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2642

As far as power distribution networks go, usually (but not always) if you have wires mounted vertically above one another than it's a low-voltage circuit (i.e. 230/415v). The lines with the wires mounted in a line horizontally will be HV so most likely be 11kv minimum, potentially 32kv. If you trace your vertically-hung wires back you will get to a transformer on the HV line somewhere. The three lines can also sometimes be combined into one three-core insulated wire.

When I put the power supply in to my workshop I dug the trench, laid the conduit, pulled the cable (10mm^2 SWA) through and mounted the workshop consumer unit. Then the sparky hooked it up to both consumer units for a few hundred quid. I did all the subsequent circuit wiring inside the workshop. That's for a 40A supply from the house.

The requirement to use a Part P certified electrician doesn't exist in Scotland however, everything just has to be done to the correct standard.

31st Aug 2018 11:03am

Intercept

Member Since: 27 Feb 2017
Location: Suffolk
Posts: 587

2002 Defender 110 Td5 Black LE Java Black

Re: Power Supply to Garden Workshop

Rosco wrote:
Mrs Rosco is having a garden workshop to do her arty wool dying delivered this weekend, which will then need kitting out, insulating, etc, etc and will need a power supply running too it.

https://www.tlc-direct.co.uk/Book/7.14.1.htm has useful information for this and other types of installation.

31st Aug 2018 11:45am

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20347

Interesting. I'm no expert on it so many of you probably know a lot more than I do.
We have quite a nest of overhead lines here!

There are some very large NG metal pylons out in Wilts and South Glos. Some of which are networks across the Severn Bridge and Avonmouth etc.
Such large pylons that the have a large V formation of insulators on them and you can hear them buzzing especially in damp weather in the winter with a high load. Corona Discharge basically. Rather un-nerving if your close especially knowing they are 250kv upward minimum.

NG have a map I think on their pages somewhere. $W33T $0U7H3RN $UG4R
🇬🇧🏴󠁧󠁢󠁥󠁮󠁧󠁿🏴󠁧󠁢󠁷󠁬󠁳󠁿🏴󠁧󠁢󠁳󠁣󠁴󠁿🇮🇪🇺🇸⛽️🛢️⚙️🧰💪

31st Aug 2018 2:49pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20347

Interesting photo Corona Discharge 500kV:

Click image to enlarge

Further info:
https://en.m.wikipedia.org/wiki/Corona_discharge $W33T $0U7H3RN $UG4R
🇬🇧🏴󠁧󠁢󠁥󠁮󠁧󠁿🏴󠁧󠁢󠁷󠁬󠁳󠁿🏴󠁧󠁢󠁳󠁣󠁴󠁿🇮🇪🇺🇸⛽️🛢️⚙️🧰💪

31st Aug 2018 3:13pm

Retroanaconda

Member Since: 04 Jan 2012
Location: Scotland
Posts: 2642

The biggest transmission lines (line the one across the Severn at Aust, by the bridge) are 400kv. With the rest of the transmission network being made up of 275kv and 132kv. Distribution then generally takes over for lines at 33kv, 11kv and low voltage (230/415v).

The bigger the line, the more important it is. There are two lines feeding from Scotland into England, and the capacity of these lines being exceeded is often the reason why windfarms are required (and paid) to turn off up here. Most of the grid demand is in England after all. I heard a while back that a new third link via subsea cable in the Irish sea was being considered.

Try phoning them up and asking if they can shut down the 400kv western England/Scotland link so you can fell some trees alongside it - worth a laugh for their response

31st Aug 2018 3:17pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 20347

$W33T $0U7H3RN $UG4R
🇬🇧🏴󠁧󠁢󠁥󠁮󠁧󠁿🏴󠁧󠁢󠁷󠁬󠁳󠁿🏴󠁧󠁢󠁳󠁣󠁴󠁿🇮🇪🇺🇸⛽️🛢️⚙️🧰💪

31st Aug 2018 3:28pm

Page 2 of 3

All times are GMT

Jump to

< Previous Topic | Next Topic >

Posting Rules

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum