Electrifying a barn

[g2c]

Hello to everyone,

This is about electricity practice

In my home I have a ground rod which 'distributes' ground to my outlets.
The two phases coming from the pole goes to the counter (one through a physical 63A fuse)
then the phases go to a differential line breaker (one through a thermal 40A breaker) and are distributed to the house loads and outlets via breakers

One of the loads is a barn situated 30m from the house, connected with a cable made of 3 1.5mm^2 wires. The cable is plugged to an external wall plug.

Now I want to replace this cable by a permanent connection so I dug a .5m deep tunnel in which I burried a 7cm tube and I intend to run though the tube power (2.5mm^2 wires) and signaling/telecom.

My questions:

1) where should I connect these power wires? a) after the house differential breaker or b) directly after the counter with a new differential breaker at the barn?
2) Where should I take the ground from? a) the house ground? b) a new ground rod at the barn? in this later case I'd only need to run two 2.5mm^2 wires

Thanks a lot for your time!

 

[Nigel Goodwin]

I can't suggest anything, as I've no idea on the regulations where you are (presumably the USA?).

But, your wires don't seem very thick for a 30m feed to the barn?, do you only have very low power requirements?, and presumably you use a mix of 120V and 240V sockets, so would need a neutral wires as well.

For the amount of bother digging a trench (and I'd suggest a bit deeper anyway) and running a pipe, I'd prefer to run some decent size wires through it - at least 4mm, and perhaps 6mm (due to the high currents at 120V).

Whatever you're planning running in the barn, you're likely to soon exceed the capacity of 2.5mm.

 

[Beau Schwabe]

Where we live in the US, I have a house, Barn, and a guest house ... ALL three structures are considered separate from one another and each require their own meter. And yes, that means 3 electric bills.

 

[g2c]

Nigel Goodwin : It's in Israel (230V) and the power requirement is low: few electric tools consuming ~500W even if I assume ~2kW ~10A
resistance @30m is 1.6*10^-8 * 30 / 2.5*10^-6 ~ 0.2ohm so each wire would drop 2V, total drop 4V should not be a problem. Regarding the
'regulations' well, nobody here to control so I just want to do it right whatever the regulations.

Beau Schwabe whatever the configuration, joules will be metered even if in just one bill

 

[ronsimpson]

Because we don't know what requirements there are for where you live ...… 220 only 110/220 ??
Look at the wiring you have now. The barn will be wired much the same as a stove, dryer, hot tube or any other large item.

My house has a main breaker for the entire house. (50A or 100A or 200A) It cuts off both line1 and line2.
Next are many little breakers 20 or 30A for lights and plugs.
There is a 100A breaker for the oven. 50A for the stove. 100A for the hot tube. 50A for a welder in the garage. These are all double breakers (L1 & L2).
It is ok to have the total of all the breakers to be larger than the main breaker. Not all loads will be on at the same time.

I would add a new breaker to the box just like adding a second stove.
Where I live you need to run Line1 (optional line2) neutral, ground. Then add a ground rod at the barn and connect it to the barn. Years ago the barn would use the house ground but that was not strong so now the barn used a ground rod and the house ground.
--edited--
I see 230V:
Add a 20A or 30A breaker. You will need lights and more.
In my case; I do not like having tools and lights on the same service. If my tool pulls too much power and kills the power then the lights go off. It is very dangerous to be working with power tools at night and have the power go off because I did something bad. BANG and every thing is dark and I do not know if I am alive or dead. I can not find my way out of the barn. So I have the lights on a different breaker and different wires.

 

[KeepItSimpleStupid]

In the US;

"detached structures" in the US require their own ground rod.
G, N, L1 and L2 are sparated at any sub-panels.

Panels are known as "Main breaker" and "Main Lug"
"main lug" panels do not have a breaker that turns off the entire panel.

Above a certain number of circuits in the sub-panel, you must use a "main breaker" panel.

To use a "main breaker" panel as a sub-panel, you:
1. Need an ground bar kit
2. You need to sever the neutral-ground bond
3. ground rod required if structure is "detached"

The main breaker panel breaker can be >the fed fuse.e.g. 60A feed in the main panel, 200A main breaker in sub-panel.

Edit: Added In the US

 

[Nigel Goodwin]

Nigel Goodwin : It's in Israel (230V) and the power requirement is low: few electric tools consuming ~500W even if I assume ~2kW ~10A
resistance @30m is 1.6*10^-8 * 30 / 2.5*10^-6 ~ 0.2ohm so each wire would drop 2V, total drop 4V should not be a problem. Regarding the
'regulations' well, nobody here to control so I just want to do it right whatever the regulations.

Basically you need to check what the local regulations are - but electricity regulations in Israel are a bit esoteric for these forums - there's been a few Israelis on here, but none have ever mentioned such things.

 

[g2c]

Hello again, Attached here a schematic drawing of what I intend to do. Just as a reminder, 230V, single phase, 40A contract.
I know that regulation matter and yet, proper design prevail to my very modest opinion so please tell if you see an issue

with this.

BTW, if IEC (Israel electric cy) were so well founded we wouldn't face so many shortage to the point that I had to purchase a UPS for my arduinos, and router-modem

 

[ronsimpson]

Where I live the ground is dry and ground rods do not work as well as they should. It does not hurt to have more than one.

 

[Nigel Goodwin]

Where I live the ground is dry and ground rods do not work as well as they should. It does not hurt to have more than one.

I remember reading an excellent article about doing the PA for LARGE gigs - and as part of the power requirement they specified three phase, with a SOLID neutral. For the earthing requirements, they weren't prepared to accept the supplied ones - and so carried with them a number of large earth rods, PLUS sacks of salt to make brine to soak in the ground round the earth rods to ensure good conductivity.

So multiple rods, as deep as you can go - and sprinkle with salt water occasionally

Dry ground isn't an issue here - its raining yet again - after the wettest June on record, following the driest May on record.

 

[Nigel Goodwin]

Hello again, Attached here a schematic drawing of what I intend to do. Just as a reminder, 230V, single phase, 40A contract.
I know that regulation matter and yet, proper design prevail to my very modest opinion so please tell if you see an issueView attachment 125823 with this.

BTW, if IEC (Israel electric cy) were so well founded we wouldn't face so many shortage to the point that I had to purchase a UPS for my arduinos, and router-modem

Ignoring any unknown regulations, I would still say use thicker cable - or run two pieces of 2.5mm to give you double the capacity, and a 100m drum would give you some left over for 'extras'.

 

[ronsimpson]

If you are going to be digging in the ground:
I have dug ditches for electricity, water, air, internet wires. What a pain.
Next time I will put in a 1" to 4" pipe. Then I can add more things later. Leave a pull string so you can pull in another wire later.

 

[mab2]

looking at your schematic, you are taking the barn supply from the 40A line breaker - so the cable to the barn must be sized to handle the max continuous current the 40A breaker can supply (if it's an en60898 breaker thats about 46A) so you need 10mm2 - might get away with 6mm2.

If you're using 2.5mm2 i suggest you protect the cable with a 20A line breaker or less.

I cannot advise on Israel regs or on what makes for effective earthing there. I would think a local earth rod at the barn would be sensible - if the barn is the steel frame type then earthing the steels is probably required (it is here (uk)) and they usually make good earth rods where they bolt into the foundations.

 

[KeepItSimpleStupid]

Generally, you don't break neutral.

I would suspect that ground, Neutral and Line should be run from the house to the barn.

The house to pole probably has a ground wire too.

So, the barn keeps ground and neutral separated except there is a ground rod for lightning and other stuff.

In the US, set up one system that had a neutral breaker. It was 90A, 3 phase, 208 and it was a Telmark ebeam power supply.

 

[g2c]

Few pics of the work. The cable -15mm internal diameter sleeve- runs in a PVC tube, in the ditch and then, unseen along the pétanque so that intruders won't find it easily. In the sleeve 2x2.5mm2 wires that should do, considering my residual life expectancy, also a 4 pairs ftp ethernet cable and a 4 pair phone cable for inter arduino serial (uart) communication, using differential transceivers - suggestion are welcome. The enet will run from the barn's arduino enet shield, through a switch, to the home's router modem. Per mab2 suggestion, i'll have 20A breaker so that in case if a 'clean' overload, equal and opposite current overload, I won't risk to melt the wires nor run home to re-establish the juice

 

[KeepItSimpleStupid]

Why bother with "phone cable"? Make it CAT6 or better.

 

[KeepItSimpleStupid]

Am I reading those pictures as, the "The PVC tube will fill with water"?

 

[g2c]

no, the pvc tube helps prevent rodent from chewing the cable and get accidentally electrified. Also, it'll facilitate future upgrade if I happen to leave too long

 

[Nigel Goodwin]

Am I reading those pictures as, the "The PVC tube will fill with water"?

Probably so, but that's no reason not to do it - you can't just bury mains cables in the ground, unless you use armoured cable (as you should really) - but a MUCH cheaper alternative is to place it in piping (even in hose piping) to give it a lesser degree of protection, but still FAR better than nothing.

If you can use a decent size pipe, it also gives you the option of replacing the cable by 'pulling it through', or even adding extra cables at a later date.

If you've got a digger, and a supply of 'free' pipes you could even fit big sewage pipes so you could walk (crouch) through them.