Voltage drop over long run to shed

tedimc

Hi folks,

have a shed nearly 500m from the house and wanted to supply power for a few lights and perhaps a winch or a few power tools.

Reckon 10amps would be loads. Talking to an electrican at the weekend and he reckoned I may need 16mm square pwa due to the voltage drop over that long a distance. Out of interest, asked in a local electrical suppliers for the price and explained the long run, but they worked it out at around 25mm square was needed.

Either way, the cost is going to run into thousands on cable alone. Is this worth doing and what size cable should I go for? Or am I better asking the esb to put Ina separate supply and see if that will work out a lot cheaper.

Sir Arthur Daley

A seperate connection would be a better overall solution. A standard esb connection is just shy of €2k.

freddyuk

Consider battery system with solar re charge. Depending on your actual loads this could be a fraction of laying cable.

2011

tedimc wrote: »

Hi folks,

have a shed nearly 500m from the house and wanted to supply power for a few lights and perhaps a winch or a few power tools.

Reckon 10amps would be loads. Talking to an electrican at the weekend and he reckoned I may need 16mm square pwa due to the voltage drop over that long a distance. Out of interest, asked in a local electrical suppliers for the price and explained the long run, but they worked it out at around 25mm square was needed.

There is no cheap solution to this.

The biggest issue that you have to deal with here is volt drop. For a given load this is dealt with by selecting a larger (more expensive) cable.

According to table A52-J3 of ET101:2008 there is a volt drop of 2.9/mV/A/m (installation method C & E) for a 16mm sq. XLPE cable.
So the total volt drop would be 0.0028 x 10 x 500 = 14.5 volts. Although these values are considered "conservative" they do not take into account the volt drop from the ESB meter to the main distribution board or the volt drop within the shed itself. The problem is that 525 states that the maximum permissible volt drop is 4%, which is 9.2 volts.

My advice would be to see if the load can be reduced, this will reduce the cable size. First of all select energy efficient lighting.
Would it be practical to operate one tool at a time? What is the rating of the largest power tool?

Sir Arthur Daley wrote: »

A seperate connection would be a better overall solution. A standard esb connection is just shy of €2k.

Agreed, the best solution would be a separate supply.

The main problems with this are:
● This may cost far more than €2,000 (depends on many factors) -I suggest you get a quote.
● There will be a monthly charge associated with the shed.

Time to cut down the money tree

2011

freddyuk wrote: »

Consider battery system with solar re charge. Depending on your actual loads this could be a fraction of laying cable.

Solar would be far too expensive to install and maintain.
Then there are issues during overcast days as well as having to have lots of batteries.

I would rather buy a small generator than do this to be honest.

2011

2011 wrote: »

Solar would be far too expensive to install and maintain.
Then there are issues during overcast days as well as having to have lots of batteries.

Depends entirely on the frequency of use.
I'd take it you haven't got/used PV with a statement like that.
They still work on overcast days.

600W solar = €750 installed
60A Charge controller = €250
2 x 1.2kW 12V second hand inverter = €600
4 x 6V semi traction batteries new = €600

2.65kWh storage to 50% DOD of batteries.

Rough figures (compensated for charging/inverter inefficiencies);
2.9kWh on a sunny day.
1.5kWh on an overcast day.
160Wh in Winter.

+15% on figures if using while sun is shining and not from storage.
Carbon neutral after 4 years. No standing charges or price per unit.

There's more upkeep and maintenance on a generator. Not to mention 60% waste energy in heat, noise and friction.

2011

Sir Liamalot wrote: »

Depends entirely on the frequency of use.
I'd take it you haven't got/used PV with a statement like that.

I certainly have not seen nor would I recommend a solar power workshop, no.

They still work on overcast days.

10 amps @230 volts for a couple of hours on an overcast day? I doubt that.

600W solar = €750 installed
60A Charge controller = €250
2 x 1.2kW 12V second hand inverter = €600
4 x 6V semi traction batteries new = €600

2.65kWh storage to 50% DOD of batteries.

Rough figures (compensated for charging/inverter inefficiencies);
2.9kWh on a sunny day.
1.5kWh on an overcast day.
160Wh in Winter.

+15% on figures if using while sun is shining and not from storage.
Carbon neutral after 4 years. No standing charges or price per unit.

There's more upkeep and maintenance on a generator. Not to mention 60% waste energy in heat, noise and friction.

Sounds too good to be true :rolleyes:

How many hours can the above system supply 10A for at 230 volts?
Why has this not caught on in Ireland if it is so cost effective?
How many amp hours are the batteries?
All generators have the losses and maintenance you mention including the ESB's.

2011

I'm not selling anything.
It's just a look at the alternative.

2011 wrote: »

How many hours can the above system supply 10A for at 230 volts?

Assuming my spec. as a suitable example although I'd be inclined to get more storage for less with used forklift batteries.
440Ah @ 12v = 2.6kWh to 50% capacity from storage and 1.8kWh from incoming photons. = 4.4kWh - ~10% inverter inefficiency = 3.95kW/h / 2400W load = 100mins overcast day
2hrs20mins on a sunny day.

Actually less if you want to get into the nitty gritty of battery discharge curves or more with greater storage.
Assuming a full 10A discharge (load spread over two inverters 5A per inverter...best have two; redundancy system).
Obviously it would be required to tailor the system to demand.

Not a lot but then. However I'm guessing 10A is just an arbitrary figure as a potential maximum, given the actual demand is

tedimc wrote: »

for a few lights and perhaps a winch or a few power tools.

Generally motors and power tools are rated for the in-rush not the running load. So expect a lower consumption than these back of a cigarette packet maths might allude.

Also power tools have mostly start stop run time so the kWh is not a fair figure to use here.

If the shed has some downtime between use you don't have to worry about maintaining the capacity as it's replenishing in the downtime.

2011 wrote: »

Sounds too good to be true :rolleyes:

Maybe you'd appreciate this (link)

2011 wrote: »

Why has this not caught on in Ireland if it is so cost effective?

Might have something to do with sparkies recommending generators every given opportunity.

2011 wrote: »

How many amp hours are the batteries?

440Ah parallel, series. Shop around, have a look at ex-service deals...it's just an example.

2011 wrote: »

All generators have the losses and maintenance you mention including the ESB's.

All combustion based generators...indeed.

Bruthal

Sir Liamalot wrote: »

Generally motors and power tools are rated for the in-rush not the running load. So expect a lower consumption than these back of a cigarette packet maths might allude.

So a 1kw motor is really only a 100 to 150 watt motor?

2011

Sir Liamalot wrote: »

Assuming my spec. as a suitable example although I'd be inclined to get more storage for less with used forklift batteries.

Used batteries?
Why do you think someone is replacing these batteries?

440Ah @ 12v = 2.6kWh to 50% capacity from storage and 1.8kWh from incoming photons. = 4.4kWh - ~10% inverter inefficiency = 3.95kW/h / 2400W load = 100mins overcast day
2hrs20mins on a sunny day.

So when you start off the batteries are 50% charged?
The you add further charge from the solar panels?
How do you charge them to 50%, from another source?

At best 1 hour and 40 minutes of use on an overcast day :eek:

Not much use really.
I don't think that running down your second hand batteries will do them much good either.

For the prices you quoted I could buy a brand new 5kVA generator and have enough change to buy a spare.

Generally motors and power tools are rated for the in-rush not the running load.

This is incorrect.
A motor rated at 1kW motor will in fact output 1kW of power and when it does the input will be higher as no motor is 100% efficient.

The current marked on the nameplate of a motor is the full load current (unless otherwise stated). The starting currents are often far higher depending on the starter type.

If the shed has some downtime between use you don't have to worry about maintaining the capacity as it's replenishing in the downtime.

Not during hours of darkness and if your batteries are flat and it is overcast the following day you are bunched!

Maybe you'd appreciate this (link)

I would be more interested in seeing a good example of an Irish one.
The reason that these systems are more popular in the UK & Northern Ireland is because of government grants.

To be honest this example looks a bit amateurish to me, more like a student project for lentil eaters.

Interesting project, yes.
But practical for a shed with power tools? No
Second hand inverters and second hand batteries, seriously?

Might have something to do with sparkies recommending generators every given opportunity.

Like it or not most of the country is fed from generators.
In fact according to Sir Arthur Daley a generator would be the "best overall solution"

Might have something to do with sparkies recommending generators every given opportunity.

Are you seriously suggesting that photovoltaic solar panels are not catching on because electricians are more interested in selling generators? I have no doubt that there are electricians out there that sell generators, but I have yet to meet one. I would have thought that it would be far more lucrative to install solar panels.

My understanding is that the best way to utilise solar power is to sell or use the electricity as it is generated, not to store it. Battery stored solar power has gone out with the indians. There will always be someone that wants to "live off grid" and will tell you that it is the best thing since sliced bread, but they are few and far between.

Bruthal

Bruthal wrote: »

So a 1kw motor is really only a 100 to 150 watt motor?

It's whatever it reads on an ammeter. Which more often than not is not what's written on the side of it.

2011

Sir Liamalot wrote: »

It's whatever it reads on an ammeter. Which more often than not is not what's written on the side of it.

That conflicts with your position in post #8 which was "Generally motors and power tools are rated for the in-rush not the running load."

Sh1tbag OToole

Go with a single 100w panel, couple of used car batteries in parallel or a marine deep cycle battery or Lifepo4 battery if you want to splash out a few 100 quid. For lights get some 12v LED ones that run directly off the battery.

You can get a decent 1 or 2kw used inverter, try and get a pure sine wave one because motors will run much smoother off one.

If you have bother with the battery running out you can always get more later or buy a generator.

2011

Sh1tbag OToole wrote: »

Go with a single 100w panel, couple of used car batteries in parallel or a marine deep cycle battery or Lifepo4 battery if you want to splash out a few 100 quid. For lights get some 12v LED ones that run directly off the battery.

So with 100% efficiency for the batteries, inverter and solar panels as well as 10 hours of ideal conditions you will be able to provide the OP with 10 amps for less than 30 minutes :rolleyes:

If you have bother with the battery running out you can always get more later or buy a generator.

Or you could just use the generator for everything and save yourself a lot of hassle

Bruthal

Sir Liamalot wrote: »

It's whatever it reads on an ammeter. Which more often than not is not what's written on the side of it.

Ammeter will read the current supplying the motor for its present mechanical loading. Loading can vary from none to full. So that reading can vary quite a way anywhere from the motors rating, downwards to unloaded current.

The ammeter won't be reading the starting current during a run test. So that's not agreeing with the rating being it's starting current.

gctest50

pair of transformers and run 10kv ground return ?


losses though....

not long enough distance to be worth it though - and simple wins

.

2011

2011 wrote: »

Used batteries?
Why do you think someone is replacing these batteries?

Telecom's, emergency standy-by systems, forklifts etc. All throw out decent batteries that are old but serviceable. They won't have their plated capacity but they are near scrap prices and for running odds and ends are still entirely viable.
Overall you can get a much better price per kW if you look around, sort the good from the bad and sell the bad for scrap lead.

2011 wrote: »

So when you start off the batteries are 50% charged?

100% but discharged to 50% for maintenance reasons (cell longevity...return on investment).

2011 wrote: »

The you add further charge from the solar panels?

Lead acid charge efficiency 85%, use the power directly then what's coming from the panel goes direct to load.

2011 wrote: »

At best 1 hour and 40 minutes of use on an overcast day :eek:

If the OP is using 2.4kW out of the gate until the cows come home.
As I say entirely based on frequency of use.

2011 wrote: »

Not much use really.

Application dependant

2011 wrote: »

I don't think that running down your second hand batteries will do them much good either.

Not good for any battery thus the 50% rule

2011 wrote: »

For the prices you quoted I could buy a brand new 5kVA generator and have enough change to buy a spare.

Sure and waste 60% of your fuel on running it. Then waste more on what it's producing but you're not using. That's how we do it.

2011 wrote: »

This is incorrect.
A motor rated at 1kW motor will in fact output 1kW of power and when it does the input will be higher as no motor is 100% efficient.


The current marked on the nameplate of a motor is the full load current (unless otherwise stated). The starting currents are often far higher depending on the starter type.

Granted. I've little experience with industrial motors. Half the electrical items in my life are running well under their ratings.

2011 wrote: »

Not during hours of darkness and if your batteries are flat and it is overcast the following day you are bunched!

50% or they will be bunched.
Then you'd need a larger system.
So far all we have to go on is

tedimc wrote: »

Reckon 10amps would be loads.

2011 wrote: »

I would be more interested in seeing a good example of an Irish one.
The reason that these systems are more popular in the UK & Northern Ireland is because of government grants.

Here was me thinking some people might care about climate change.
There's no feed in tariffs for batteries. There is a lesser incentive in the UK for what you use but don't buy from the state.

Irish are slow to adapt anything: we're still putting radiators under windows behind curtains and non-mixing hot and cold taps.

It's a similar climate and fit for purpose.

2011 wrote: »

Second hand inverters and second hand batteries, seriously?

I think we have very different ideas what takes place in a shed. For DIY; yes it can work and work well. For a fully tooled home run commercial workshop then no it's not viable.

2011 wrote: »

Are you seriously suggesting that photovoltaic solar panels are not catching on because electricians are more interested in selling generators?

Nope. I'm just advocating the restraint of swatting flies with cannonballs. Generators waste more energy than they supply that is all. The benefit to having alternatives is you can take them or leave them.

2011 wrote: »

My understanding is that the best way to utilise solar power is to sell or use the electricity as it is generated, not to store it.

True. In this instance it would still require a mains connection so there's little to be gained.

2011

I am not going to argue around in circles about this.

I think that solar power will be part of the solution to the energy crises that we face. There are lots of advantages to solar power such as low maintenance and almost no moving parts (so low mechanical wear). If we had the same grants and / or tax incentives that they have in other countries I have no doubt that they would be far more popular here.

However they work best when used in conjunction with another system, not as the only source of power. When used with batteries they become a far less attractive option and the carbon footprint increases dramatically.

In this instance I would think that they are an expensive and unreliable choice. The fact that they are so infrequently used in this way speaks for itself.

Bruthal

gctest50 wrote: »

pair of transformers and run 10kv ground return ?


losses though....

not long enough distance to be worth it though - and simple wins

.

Pair of transformers would work fine. But 500 metres of 10kv rated underground cable or overhead line with poles, not to mention the transformers, would be some price I'd say.

It was the first thing in mind myself when I seen 500 metres to shed, but not a serious thought though.

2011

2011 wrote: »

I am not going to argue around in circles about this.

I've no desire to either. I'm outta here.

2011 wrote: »

However they work best when used in conjunction with another system, not as the only source of power. When used with batteries they become a far less attractive option and the carbon footprint increases dramatically.

I agree in the normal run of things. For a shed with a lot of downtime however I think is a suitable application.

Lead acid batteries are wholly recyclable.

2011 wrote: »

In this instance I would think that they are an expensive and unreliable choice.

I've lived on batteries 5 years, no power cuts...that's a bit more reliable than the state iirc.

2011

Sir Liamalot wrote: »

I've lived on batteries 5 years, no power cuts...that's a bit more reliable than the state iirc.

Really? Now that is interesting.
Are you saying that you have no connection to the ESB ?
Is all of your electrical power solar?

I would be very interested in hearing from someone with direct experience.

It's a lot simpler than you think. :pac:
Currently I'm outsourcing a workshop but looking to up-scale and searching for a site in the UK to plant my battery powered workshop on. The house will have mains due to marital reasons.
Wholly PV March to October, diesel as a secondary, mains on rare occasion and still tinkering with wind for the rest of the year but I may just scrap the notion and triple my PV.

I reckon my consumption has increased lately on my previous 16kWh per 6 months. I'll post updated controller figures at the end of the month.

Sh1tbag OToole

2011 wrote: »

So with 100% efficiency for the batteries, inverter and solar panels as well as 10 hours of ideal conditions you will be able to provide the OP with 10 amps for less than 30 minutes :rolleyes:



Or you could just use the generator for everything and save yourself a lot of hassle

I don't know if the OP wants to draw the full 10A for the whole day or just drill a few holes. Even with a generator it's probably worth the trouble of having the lights running off 12V batteries. Not worth it to have a generator running under feck all load

Sir Liamalot

And another thing...:pac:...best correct myself now....

Sir Liamalot wrote: »

Actually less if you want to get into the nitty gritty of battery discharge curves

If discharging a battery at the C3 rate (complete discharge in 3 hours) the discharge curve will only allow for 30mins of runtime (to 50%) from storage and the batteries won't live very long.

I was working under the notion that the OP is probably more likely in and around <5A intermittent @240V for nominal operation and saying 10A for merit.

Working to a 2.4kW sustained load, realistically to keep a healthy bank you'd need to work to the C20 rate which means 1200Ah @ 48V and 10 hours runtime so no room in the shed with all them forklift cells and ~2kW PV to support them.

freddyuk

freddyuk wrote: »

Consider battery system with solar re charge. this could be a fraction of laying cable.

Well let's try again.....

The question still not answered is ... "Depending on your actual loads"
So tell us what the daily average load and peak load requirement is ... and then we can have a sensible discussion about renewable energy options.

If your work load can be adapted to the stored power available you can "work with nature" by adapting your lifestyle to use renewable energy much more effectively. Anyone living off grid will understand that you do the washing, hoovering and baking on the good solar days.
If you are using high powered tools all day, day in day out then hopefully your business is financially sound enough to have the power cable laid and paid for. A generator running all day may become tiresome and expensive.

A generator can be tied to a solar system and work in tandem with it to cover high short term peak loads automatically. Thus a smaller generator can be used as you have constant solar input for smaller loads long term loads. it's all about balance.

markad1

better put the kettle on at 8 for a cuppa at 10

2011

Sir Liamalot wrote: »

It's a lot simpler than you think. :pac:

Impressive, fair play.

Will have to agree to disagree with you on the shed though

markad1

markad1 wrote: »

better put the kettle on at 8 for a cuppa at 10

Gas hob or induction hobs are v. efficient if you can run them at >C5 with a true sine wave.

tedimc

Thanks lads for all your input - its greatly appreciated!

To address some of the questions,
it will not be a fully fledged workshop or anywhere near
- 12V lights would be fine
- 10A will be a worst case scenario and I could probably reduce the load, but the cost differential of laying 6mm/10mm armoured versus 16mm/25mm doesn't appear to be actually that much.
- Load would be made up of outdoor light, internal light, maybe a security camera, a bit of light drilling. However, it would be nice to also have the option to plug in a welder down there if needs be.
- Realistically, tooling will be used 2 days per week max and probably only for an hour or so at a time.
- I'll investigate the mains connection and see what it costs in connection fees, and on-going charges.
- Will also look into the solar and generator as an option. Might come to that if mains connection or spur of the house is running into the €2k+ mark.
ㅥ

.G.

Build a new shed a lot nearer the house

evosteo

set up your own supply, invest in a diesel generator like something similar. maybe size it bigger if planning on expanding the shed.

http://www.ebay.ie/itm/5KVA-SILENT-RUNNING-LDE6800T-DIESEL-GENERATOR-5KVA-/380267759845




hard wire it to a distribution board in your shed. consult a qualified electrician about the idea. the earthing will need to be up to a high standard if there is livestock involved.

just top up your generator as you need it. or have a separate tank supplying the genny.

i think agricultural diesel (if you are legally obliged to use it) is ok to use with these diesel generators so you would save an extra few bob vs standard diesel

i think this is the simplest option for you

steve