A simple solution.

Billy Bunting

Power cuts! :mad:

I live in the back of beyond and still have to endure ESB power cuts, i did recently invest in a small 5hp Honda Geny, my thoughts (but no bottle totry it) are that during a power cut because i have power going out to the sheds i could perhaps simply plug in the Geny in the shed, turn off the supply power switch and have power for the house lighting at least, i have heard that some type of diode thingy needs to be fitted, that being beyond me i wondered if my idea held any water or am i missing something?? failing that just how difficult is my simple solution going to be ???

M cebee

i've had a few cans but it still seems very dodgy and pointless trying to backfeed it

you'd have no proper changeover for a start

bassey

Having a genny without a proper changeover switch is absolutely fùcking lethal, sorry but it's very seriously putting an ESB Network Technician's life in danger. If you plug you geny into your home circuit it energises backwards onto the network, you're 240V supply goes back through your local traffo and then then 10/20KV network is energies up to the point where either the fault is or it's been switched out.

If you're going to have a genny hooked make sure it has a proper changeover switch fitted.

Billy Bunting

Thanks for that, and I do get your point, thats why i always intended turning off the double poled supply switch, presumably if it workes for the ESB it would work for me. But it sounds from your reply that all the little solution requires is this changeover switch, is this much of a job to fit and anyone supply a link to one available ??

Bruthal

bassey wrote: »

Having a genny without a proper changeover switch is absolutely fùcking lethal, sorry but it's very seriously putting an ESB Network Technician's life in danger. If you plug you geny into your home circuit it energises backwards onto the network, you're 240V supply goes back through your local traffo and then then 10/20KV network is energies up to the point where either the fault is or it's been switched out.

If you're going to have a genny hooked make sure it has a proper changeover switch fitted.

I would imagine the esb personel will take precautions with bridging and earthing lines they are about to work on to prevent this type of event, as well as protecting engineers in the remote posibility of the lines they are working on actually being switched back on.

But its still not something that would want to be happening, and certainly presents dangers without any doubt. A proper changeover switch is essential to either automatically or probably in this case, manually swap the supply to your installation from the esb to the genny and back again.

Bruthal

M cebee wrote: »

i've had a few cans but it still seems very dodgy and pointless trying to backfeed it

you'd have no proper changeover for a start

No advising when under the influence:D

bassey

robbie7730 wrote: »

I would imagine the esb personel will take precautions with bridging and earthing lines they are about to work on to prevent this type of event, as well as protecting engineers in the remote posibility of the lines they are working on actually being switched back on.

The first thing an NT will (should) do when working on a line is earth it, but imagine this scenario.

If yer man has his genny running it means there's an outage, if there's an outage there's probably some poor on call NT going out looking for the fault and if possible fixing it. So lets say there's an outage in the middle of the night caused by terrible weather, you could have a sleep deprived NT trying to fix something as quick as possible and he doesn't bother putting on the earths because he just wants to get out of there, the last thing he wants to be thinking about is a back feed going to fry him. I know it's a small chance but still.

Also even when the line is earthed the ground around the earthing rod will become live and anyone near it would be susceptible to step voltage and the last thing anyone wants is a step voltage running up one leg, through their goolies and down the other leg!:P

Billy Bunting

Thanks very much for the ticking off, but could i get the advice now please ??

How do i go about fitting this genny to do the job discribed ??

Bruthal

bassey wrote: »

The first thing an NT will (should) do when working on a line is earth it, but imagine this scenario.

If yer man has his genny running it means there's an outage, if there's an outage there's probably some poor on call NT going out looking for the fault and if possible fixing it. So lets say there's an outage in the middle of the night caused by terrible weather, you could have a sleep deprived NT trying to fix something as quick as possible and he doesn't bother putting on the earths because he just wants to get out of there, the last thing he wants to be thinking about is a back feed going to fry him. I know it's a small chance but still.

If its a 10kv/20kv fault it will usually be switched to isolate the section of line with the problem. If its a 400v cable then it will be repaired. These will not be worked on without full precautions i would of thought. The only thing likely to be done by a sleepy sparks without this is replace a fuse/fuses. But of course that does not mean the genny scenario suggested by the OP is safe and not without serious dangers.

Also even when the line is earthed the ground around the earthing rod will become live and anyone near it would be susceptible to step voltage and the last thing anyone wants is a step voltage running up one leg, through their goolies and down the other leg!:P

The genny would be feeding into Live and Neutral from the house. The neutral being earthed as per tn-c means bridging phases to neutral cant really have an earth rod now becomming live if it was a 400v cable being worked on. I dont know what their procedures are these days on that. There are of course dangers as i already said, i did not say its fine and danger free, and can of course be a potential serious hazzard.

There certainly would be a danger if a 400v cable from a transformer to a mini pillar was being cut to remove a damaged section and now the genny is feeding onto the now open end going to the mini pillar with a sparks going to joint it, unless the mini-pillar phases and neutral are also bridged out, again i am not sure of the procedures but that would seem a viable precaution. But a mini pillar would likely be feeding a few other houses and the 5HP genny will be trying to supply these and potentially anything on the other side of the ESB 10kv traffo, and likely again would just cut out. But might not of course, especially at night with not much loads on.


If its the other side of a 10kv traffo where the problem is, and all 3 phases are bridged and connected to ground, i cant see a genny in someones house being connected to that and maintaining it and keeping on running, even though its only a single winding in the secondary side of the traffo now being fed by the genny, as bridging out all 3 phases on the primary side would still be an overload to the genny feeding from the secondary side . They would probably be bridged out in any possible location they could potentially become live.

But anyway, you are right of course, that type of thing with generators has very serious potential hazzards no matter what precautions may be taken. It would be interesting to know what precautions are taken with regards to this.

Bruthal

Billy Bunting wrote: »

Thanks very much for the ticking off, but could i get the advice now please ??

How do i go about fitting this genny to do the job discribed ??

I would not say he was giving you a ticking off, just rightly pointing out the seriousness of just connecting the generator without the proper switch to ensure it cant feed out onto the esb network.

Anyway, what you want is a manual or automatic changeover switch (manual would likely be most suitable for a manual start generator) which you can operate or operates automatically when you have a power cut, then you start your generator.

This would mean you are selecting whether to feed your MCB/fuseboard from the ESB supply or your generator. You would likely have to avoid using high load items, or the generator would not be able to keep going, or would trip any breaker it might have. To keep lighting going would work fine. You could possibly even have the changeover switch just feeding your lighting and maybe a socket for times when supply is lost, but overall in answer to your question, a change-over switch is required and needs to be fitted by a sparks.

bassey

You're right of course, the first thing any NT and any ESB apprentice does when they start is learn the earthing techniques, on LV this is simply bridging the 3 phases and neutral together on the overheads. On MV though a rod is driven into the ground and connected to a phase and then the phases bridged out. But usually if an NT becomes aware of any back feeds by doing his voltage checks he'll just earth it so as to knacker the genny.

Bruthal

bassey wrote: »

You're right of course, the first thing any NT and any ESB apprentice does when they start is learn the earthing techniques, on LV this is simply bridging the 3 phases and neutral together on the overheads. On MV though a rod is driven into the ground and connected to a phase and then the phases bridged out. But usually if an NT becomes aware of any back feeds by doing his voltage checks he'll just earth it so as to knacker the genny.

Yea on MV i said all 3 phases are bridged and earthed, although i didnt mean in that order:eek:, as abviously going and bridging the phases first would not be great if it was still on, so earthing a phase first is the procedure which probably would show its off. I thought i remember they used to touch each phase first with the earthed clamp when i was there as apprentice, then earth one and bridge the 3 phases, although the way 10kv earth faults are treated now back at the 38kv station is different these days. And now the 20kv system is in too.

bassey

Yeah that's pretty much it, the exact procedure is

Receive Proof Of Disconnection -> Carry out check for loss of voltage -> Earth S phase -> Bridge R and T phases to S phase

Billy Bunting

robbie7730 wrote: »

I would not say he was giving you a ticking off, just rightly pointing out the seriousness of just connecting the generator without the proper switch to ensure it cant feed out onto the esb network.

Anyway, what you want is a manual or automatic changeover switch (manual would likely be most suitable for a manual start generator) which you can operate or operates automatically when you have a power cut, then you start your generator.

This would mean you are selecting whether to feed your MCB/fuseboard from the ESB supply or your generator. You would likely have to avoid using high load items, or the generator would not be able to keep going, or would trip any breaker it might have. To keep lighting going would work fine. You could possibly even have the changeover switch just feeding your lighting and maybe a socket for times when supply is lost, but overall in answer to your question, a change-over switch is required and needs to be fitted by a sparks.

Thanks for that Robbie.