ESB cable under public roadway. Allowed?

sat matt

Hi folks

Sorry if this isn't the correct place to post. Before I continue I will say that this is a completely unknown area to me so apologies when I come across completely ignorant! I've looked around but I can't seem to find anything to answer my question

I'm mulling a project over in my head here and part of it would mean getting power from an ESB pole which is on the other side of a regional (R) road. The pole in question is carrying the 10kV 3-phase network so I'm just making the assumption for now that getting a connection would mean the ESB would pop a step-down transformer on the pole and pull off this

My question is about the road crossing. My thinking would be we'd mole trench and duct deep under the road (with any relevant permissions granted) to meet the pole on the far side as the thought of a pole(s) being erected to cross the road just seems wrong to me... and this area is blighted with poles as it stands. However I've definately heard a number of times in the past that the ESB really frown upon running cables under public roads. I can't recall the exact details or reasons given but I do recall they were discussing much higher power links in all instances (an industrial site sharing a transformer for example)


Can anyone enlighten me a little. Would the ESB allow a ducted LV connection under a regional road or is it a non-runner? I know the ESB themselves commonly bury very heavy connections under regional roads around here for the likes of wind-farms but that would be their own work and their own rules I imagine

Thx

Victor

Is this a rural location?

Assuming there is space, there is no particular problem running a line underground. It would however depend on how much of the farmer's land has to be crossed underground. Digging up a main road has it's complications, while a mole could be expensive.

Doing an overhead line would likely be much cheaper and would mean using just one crew.

If you want to specify how they do it, expect them to bill you for the extra.

Luckysasha

The end pole must be on your property. So when you apply for a new connection the ESB will survey the job and quote you accordingly. You mention a three phase backbone line across the road, is it a three phase or single phase connection you are looking for. If it's a single phase supply you need more than likely you will end up with a pole and transformer in your garden. The will underground the service to your house from this pole

iwillhtfu

It's allowed but it can be incredibly expensive.

I've seen more than one job abandoned due to this exact scenario.

tiny timy

I done it on my build. Connection fee was exactly the same price as standard. I incurred the cost of laying the ducting from the pole to my esb box. Fed the rope through it as i was laying it. Sand on top, followed by warning tape followed by more sand.

It's alot better job if you can afford to pay for the extra ducts. No overhead cables, which also relates to no birds ****ting all over the place!!!

sat matt

Thanks for the responses folks. I'll add some detail and try answer some points raised

@Victor, yes this is a very rural R road with open bog on one side (commonage or "mountain" as the farmers call it) and where the poles run is an unclaimed strip, a small bank of land that runs to the waters edge. Access or dig permissions won't be an issue and judging by some of the repsonses, impact moling and ducting under the R road should be allowed also. There are no services under the road, only an old council water main barely buried under the grass verge

The project is a small comms tower which I've been asked to lend some thought to. I understand this end of it, I have a fair understanding of power distribution but I wouldn't be up to speed on the practices of the ESB or getting a connection from them. The tower will be about 1,100 meters from the nearest power pole and I figured the fact that the nearest poles are core 10kV network would work in our favour as we wouldn't be looking for power at the end of an over-subscribed LV spur... possibly avoiding the need for heavy network modifications, additional transformers, long runs of poles, etc.

Having worked with and from querying contractors of other isolated comms towers, the contractors ran long runs of SWA (unducted in some cases) down to an existing ESB pole. Here the ESB usually put in a small cabinet to patch the SWA into their own cable running down the pole. However it's difficult to gather what accepted practice is as standards of work vary greatly and there are many, many examples of things not meeting the requirements set out by the ESB themselves!

I guess the first step is dropping into the local ESB office and requesting a connection. I wouldn't intend on "specifying how they do it" as you say but I and others would be greatly against poles being run, even if just across the road. Where the existing poles are is particularly scenic and a few years back a contractor for the ESB done something of a hatchet job when upgrading this line. It's an eye-sore at present with poles all over the place, most of them not even erected straight. Second reason is if they cross the road with an overhead cable to meet a transformer, there's telephone cables on the far side which may need to be buried.

We would hope to approach them with something that's easy for them to work with even if it requires much more effort, cost and work on our end. The road crossing was my biggest concern so if they do in fact allow under-road ducts, this is a good start

Victor

sat matt wrote: »

@Victor, yes this is a very rural R road with open bog on one side (commonage or "mountain" as the farmers call it) and where the poles run is an unclaimed strip, a small bank of land that runs to the waters edge. Access or dig permissions won't be an issue and judging by some of the repsonses, impact moling and ducting under the R road should be allowed also. There are no services under the road, only an old council water main barely buried under the grass verge

Assuming it isn't busy, trenching sounds more practical.

The tower will be about 1,100 meters from the nearest power pole [/QUOTE]At that distance, I wonder if it would need to be higher than the typical 200-400 volt supply to most residences / businesses.

additional transformers, long runs of poles, etc.

Well, A transformer would be needed somewhere. And you need to cover that 1,100 meters somehow - by poles or trenches.

Having worked with and from querying contractors of other isolated comms towers, the contractors ran long runs of SWA (unducted in some cases) down to an existing ESB pole. Here the ESB usually put in a small cabinet to patch the SWA into their own cable running down the pole.

That sounds shoddy - what happens if in years to come someone is using a JCB to clear out a ditch or similar?

Second reason is if they cross the road with an overhead cable to meet a transformer, there's telephone cables on the far side which may need to be buried.

that can be managed by using poles of specific heights to manage the swing of the cables.

sat matt

Victor wrote: »

Assuming it isn't busy, trenching sounds more practical.

We'll have to weigh them against either I suppose. I would have thought an impact mole and duct pull would be cheaper and cleaner than cutting, trenching and repairing the roadway

At that distance, I wonder if it would need to be higher than the typical 200-400 volt supply to most residences / businesses.

Well, A transformer would be needed somewhere. And you need to cover that 1,100 meters somehow - by poles or trenches.

There'd be a voltage drop on the run alright but can be managed with the correct cable. The end load would be light though, a few bits of comms gear, most of it stepped down to low-voltage DC. Our hope would be to trench the entire run as it's open bog, so fairly easy to bury some duct, cable and tape in

As for the transformer, I would hope they'd entertain popping it on a core pole and let us feed from there but they don't seem to do this too often. They usually break two cables off from the core to a nearby pole and mount the transformer there, except for their own work for powering their telemetry units... I've seen them mount both a 3 and single phase trans on one core pole for this. We'll have to call in and see what they'll allow I guess

That sounds shoddy - what happens if in years to come someone is using a JCB to clear out a ditch or similar?

These instances would have been on exposed hill tops. I've actually saw SWA to comms tower sitting on the top of the heather (!!) but hey, it's not my place to say

air

Will it be an un-metered supply?

sat matt

air wrote: »

Will it be an un-metered supply?

I wasn't aware of these until they were proposed to me recently. Un-metered sounds good and from reading around it seems it can work out cheaper and would be less hassle than a meter + standing charge + units, etc...

One small concern I would have about un-metered connections is the 2kVa limit. This is about 1600 watts and while it's not too shabby for what it is, it's still a hard limit to be observed. I see over on some older posts on the farming forums mentions of an 8kVa un-metered connection but many of these connections seem to have required a fair bit of nudging, winking and fancy form filling... not my thing at all!

I haven't got to spend any time on it this past week so I need to get a picture of my power requirements before I go ruling anything out

Calahonda52

tiny timy wrote: »

I done it on my build. Connection fee was exactly the same price as standard. I incurred the cost of laying the ducting from the pole to my esb box. Fed the rope through it as i was laying it. Sand on top, followed by warning tape followed by more sand.

It's alot better job if you can afford to pay for the extra ducts. No overhead cables, which also relates to no birds ****ting all over the place!!!

So you dug the public road up yourself?

Tifosi

sat matt wrote: »

I wasn't aware of these until they were proposed to me recently. Un-metered sounds good and from reading around it seems it can work out cheaper and would be less hassle than a meter + standing charge + units, etc...

One small concern I would have about un-metered connections is the 2kVa limit. This is about 1600 watts and while it's not too shabby for what it is, it's still a hard limit to be observed. I see over on some older posts on the farming forums mentions of an 8kVa un-metered connection but many of these connections seem to have required a fair bit of nudging, winking and fancy form filling... not my thing at all!

I haven't got to spend any time on it this past week so I need to get a picture of my power requirements before I go ruling anything out

Small comms tower, for Who?, why would ESB supply an unmetered supply ?, Who will take the Tower in charge.

Why not make an application , discuss with the local ESB engineer

sat matt

Tifosi wrote: »

Small comms tower, for Who?, why would ESB supply an unmetered supply ?, Who will take the Tower in charge.

Why not make an application , discuss with the local ESB engineer

[edited to stay on topic]

The concept of an un-metered connection sounds like a good fit for infrastructure like small comm towers but it'll be the ESB's call as to what they supply in the end. The whole thing's barely past idea stage so a little early to make an application, other stuff to be figured out yet

Thanks for the help so far folks

air

Tifosi wrote: »

Small comms tower, for Who?

Not really a relevant query at all.

Tifosi wrote: »

why would ESB supply an unmetered supply ?

ESB Networks are in the business of installing electrical connections so they'll install one based on an application and payment for same.

Tifosi wrote: »

Who will take the Tower in charge

Not really a relevant query at all

Tifosi wrote: »

Why not make an application , discuss with the local ESB engineer

He needs to decide what type of connection he's applying for first, so you're putting the cart before the horse here.

Overall a post filled with questions not relevant to helping out the OP at all and some poor advice.

Tifosi

air wrote: »

Not really a relevant query at all.


ESB Networks are in the business of installing electrical connections so they'll install one based on an application and payment for same.


Not really a relevant query at all


He needs to decide what type of connection he's applying for first, so you're putting the cart before the horse here.

Overall a post filled with questions not relevant to helping out the OP at all and some poor advice.

Gees the air is filled tonight.

All relevant queries, work with the ESB frequently

sat matt

Tifosi wrote: »

Gees the air is filled tonight.

All relevant queries, work with the ESB frequently

From your experience, would the ESB usually provide a standard metered connection to the likes of small comm towers? Seems a bit overkill for something that would be sipping a few 100 watts constant

Also, I mentioned the 8kVa un-metered connection above. Do these exist or is it a myth I took from the farming forums?! Is 2kVa a hard limit on un-metered connections?

air

sat matt wrote: »

One small concern I would have about un-metered connections is the 2kVa limit. This is about 1600 watts and while it's not too shabby for what it is, it's still a hard limit to be observed.

ESB connections are current limited.
The standard unmetered connection has a 10A fuse so you have 2070W to play with at minimum supply voltage.
Virtually all telecoms power supplys nowadays have power factor correction included and operate with a power factor that is very close to unity so in reality you have a minimum of 2000W available - before cable losses which should be significant.
If you have a usage of only a few hundred watts then the whole thing is very straightforward. If it's only over 2000W at certain times you could use a battery bank to get through the peaks and operate the PSU in output current limitation mode to ensure the supply capacity isn't exceeded.

ESB will provide a metered supply for a few hundreds watts no problem, my own house only averages 200W over the course of the year.

The most practical approach to this installation will be to install a metering or demarcation cabinet near the source of ESB supply and have ESB complete their works to there. Look after the run from there to the tower yourself.

The key aspect that will define how best to do it is the power consumption and load profile.

air

Tifosi wrote: »

Gees the air is filled tonight.

All relevant queries, work with the ESB frequently

Who the connection is for makes no odds.
ESB provide unmetered supplies.
Who takes the tower in charge is irrelevant. ESB Networks will only want to see that it has planning.
As stated, it's better to know what type of application you want to make before you approach ESB Networks.

All in all, irrelevant questions / poor advice.

sat matt

air wrote: »

ESB connections are current limited.
The standard unmetered connection has a 10A fuse so you have 2070W to play with at minimum supply voltage.
Virtually all telecoms power supplys nowadays have power factor correction included and operate with a power factor that is very close to unity so in reality you have a minimum of 2000W available - before cable losses which should be significant.
If you have a usage of only a few hundred watts then the whole thing is very straightforward. If it's only over 2000W at certain times you could use a battery bank to get through the peaks and operate the PSU in output current limitation mode to ensure the supply capacity isn't exceeded.

ESB will provide a metered supply for a few hundreds watts no problem, my own house only averages 200W over the course of the year.

The most practical approach to this installation will be to install a metering or demarcation cabinet near the source of ESB supply and have ESB complete their works to there. Look after the run from there to the tower yourself.

The key aspect that will define how best to do it is the power consumption and load profile.

A quick question about running some cable under a road has revealed much more than I expected! Great info so thanks all

A demarcation cabinet was suggested to me the other evening and makes better sense so we'll opt for it regardless of what connection we might get

As for cable loss, this will be signifigant indeed, higher than I had in mind. I had a quick chat with our spark so he's to come back on it but to give 2kW at 240v over 1,200 meters while trying to maintain 3% or less of a voltage drop will take quite a chunk of copper. I won't pretend to understand cable sizing so I'll leave it to him

air

While a smaller cable mightn't meet regs for voltage drop for a standard installation, rectifiers generally accept a really wide range of input voltages. The ones I use will work down to 90V which makes the voltage drop irrelevant apart from the energy cost of the cable losses if you have no other equipment at the comms tower - which is quite likely.
Your primary concern then just becomes using a cable big enough to generate a large enough fault current to activate whatever supply breaker you have protecting the main supply cable.
It's also possible to put a transformer at either end, I've experience with another run done with 230->690V transformers.
There is a trade off however between the cost of the cable and the transformers. The transformers will have a finite lifetime also and will need to be enclosed which adds further cost. The cable won't cost anything more once it's in.

sat matt

air wrote: »

While a smaller cable mightn't meet regs for voltage drop for a standard installation, rectifiers generally accept a really wide range of input voltages. The ones I use will work down to 90V which makes the voltage drop irrelevant apart from the energy cost of the cable losses if you have no other equipment at the comms tower - which is quite likely.
Your primary concern then just becomes using a cable big enough to generate a large enough fault current to activate whatever supply breaker you have protecting the main supply cable.
It's also possible to put a transformer at either end, I've experience with another run done with 230->690V transformers.
There is a trade off however between the cost of the cable and the transformers. The transformers will have a finite lifetime also and will need to be enclosed which adds further cost. The cable won't cost anything more once it's in.

Okay, I'll pass this bit on wholesale as it's beyond me. I do recall being told by an electrician years ago that if you "boosted" voltage, you lost amps or watts capacity... there was some trade-off basically!

I'll see what the electrician comes up with cable wise. I got to witness a cable pull in an industrial estate in the UK a few years back where they were pulling about 150 meters of cable across the yard from an onsite substation. The cable was so heavy they had to get in a huge Volvo shovel in the end to pull the cable through the duct. I never knew cable could be so big or so heavy... this stuff was like a tree trunk!! I'm already having visions of us having to run that same cable up the hillside to power a few radios

air

An experienced contractor will know how to do it in the easiest possible fashion.
If the ground conditions are as soft as you've described it could well be possible to mole in the cable directly without any excavations being required. This could be very cost effective.
The warning tape could be installed concurrently with the same rig.
Interval posts should be installed along the route to mark it further.
The transformer route would be worth looking at if you go this way, a smaller cable would go in very easily indeed.