temporary supply for marquee

[xr4x4]

How would you not export the pme? Don't run a earth in the supply cable?

 

[flameport]

How would you not export the pme? Don't run a earth in the supply cable?

If using armoured cable (which it certainly should be trailing across a field), then the armour is not connected at the load end, probably by fitting the end of the cable & gland into an insulated enclosure.

 

[Spark123]

Also rodding down the install and using RCD protection, effectively turning it into a TT installation.

As other have said though, I'd consider a generator (probably a 3 phase one) and a distro, a good generator hire company should be able to supply you with the lot.

 

[bernardgreen]

Definately a job for a generator.

QUick. efficient and the generator company do all the hard work for you.

The additional cost ( compared to a high risk connection to a domesti supply ) is well worth it for the peace of mind.

Having seen the service that Aggreko provide I would recommend them. Tell them what will be needing power and they will work out the package you need.

There are other hire companies.

 

[ricicle]

....If using armoured cable (which it certainly should be trailing across a field......

H07RN-F is perfectly acceptable as well for temporary set-ups.

 

[Buzx1313]

why would you be worried about PME being in the tent??

ESQCR which is statutory.

so where in esqcr does it say you can not export pme?

i really do not see the problem here,, if you have a supply to a tent or what ever protected by rcds then what is the problem?

 

[JohnW2]

i really do not see the problem here,, if you have a supply to a tent or what ever protected by rcds then what is the problem?

Stand with bare feel on the wet floor of the tent and hold onto some exposed-conductive part pf the exported supply whilst I introduce a break into the house supply's neutral - and, if you survive, you'll maybe at least discover something about the principle of operation of an RCD

Kind Regards, John.

 

[Buzx1313]

i really do not see the problem here,, if you have a supply to a tent or what ever protected by rcds then what is the problem?

Stand with bare feel on the wet floor of the tent and hold onto some exposed-conductive part pf the exported supply whilst I introduce a break into the house supply's neutral - and, if you survive, you'll maybe at least discover something about the principle of operation of an RCD

Kind Regards, John.

So lets get this right so we are both singing from the same song sheet..

you want to break the neutral at the cut out? yes this is possible but in reality unlikey.. so this senario is quite possible and i agree would have dreadful outcome.. this would also cause most of the house to be live if cross bonded..
also if that was the case and it was deemed so dangerous then all installtions would be TT.
so whilst i agree in principal i feel it is highly unlikey this would happen.

so the basic principle of an rcd is .. what goes out must come back. if this doesnt occur then the rcd will trip, so assuming the neutral is ok at the cutout then if you were in your bare feet and the mic became live then all should be well becuse the rcd would trip before your recived a shock great enough to kill you..

to take your theory to the extreme any extension lead you export from the house would be subject to your example, not practical at all.

also what about your shed at the bottom of the garden etc etc etc

 

[JohnW2]

...you want to break the neutral at the cut out? yes this is possible but in reality unlikey.. so this senario is quite possible and i agree would have dreadful outcome.. this would also cause most of the house to be live if cross bonded..

Exactly.

...also if that was the case and it was deemed so dangerous then all installtions would be TT. so whilst i agree in principal i feel it is highly unlikey this would happen.

TN-C-S does carry that potential serious danger (and I think probably only exists because it saves DNOs a bit of cable money). Using PME with it reduces the risk, but the risk still exists, in its worst form if the neutral fault develops between the last earthing point of the PME and the property's installation.

It's allowed because of the compulsory existance of bonding - so that, even if the whole of the house's CPs and exposed-conductive parts may rise to a high potential relative to true earth, if the bonding has effectively created an equipotential zone within the house, there should be no dangerous potential differences.

The problem in the tend is that one cannot bond a lawn!!

...so the basic principle of an rcd is .. what goes out must come back. if this doesnt occur then the rcd will trip, so assuming the neutral is ok at the cutout then if you were in your bare feet and the mic became live then all should be well becuse the rcd would trip before your recived a shock great enough to kill you..

Nope. The current through your body would have a complicated course. It would start at the L of the supply, flow through one side of the RCD, then through any loads connected to the installation, thence via the N wiring back and through the other side of the RCD, then, when it got to the cutout, it would find no path to the neutral of the supply (broken) - but. instead, would flow along the earthing conductor to the installation's MET and CPCs, along the SWA armour, through your body and then through your wet feet to true earth. The important point being that all of that current would flow equally through both sides of the RCD - hence no current imbalance and no operation of the RCD. You could well be dead.

...to take your theory to the extreme any extension lead you export from the house would be subject to your example, not practical at all.

Yep, if you use an extension lead from a PME supply in a garden, the same hazard potentially exists. That's why you should only use 'double insulated' things with such an extension, so that the PME 'earth' is not exposed anywhere.

Kind Regards, John.

 

[timbim]

Indeed in some circumstances there could exist a dangerous potential difference between the local earth potential at the marquee and the house, if the PME were exported but badly such that the body of the marquee were not bonded, then the potential for a shock when touching the frame and an accessory earthed to the house PME certainly exists, and no protective device can protect you from that. If the frame were properly bonded, then a significant current could flow along the earthing conductor, with potentially dangerous consequences.

 

[Buzx1313]

lets imagine what happens if a drunk pulls up the earth rod??

look guys you can give all the senarios you want and i aint got time to argue with you all because i am going to get ****ed..

but we have to make a risk assement of the venue, so a private wedding in someones garden i would have no hesitation in run a sub main from the house and keeping it (pme).

Glastonberry maybe is something else..

oh and one last scenario .. your cutting your lawn with your 2 core flex fed hovver mower, it cuts the lead , your in your wellies, you pick up the lead and put your thumb across the phase and neutral.. whoops..

 

[RF Lighting]

Marquee.

Metal burco boiler at PME earth potential

Caterer stood on wet ground at true earth potential.

= Injured or dead caterer.

Do not export PME earths for tents / caravans / garden supplies.

Ever.

If you have no hesitation in running out this sort of supply is demonstrates that you do not fully understand electrical principals, earthing supply types, and potential difference.

 

[ban-all-sheds]

but we have to make a risk assement of the venue, so a private wedding in someones garden i would have no hesitation in run a sub main from the house and keeping it (pme)

Yes, but that's because you are a f*****g idiot.

 

[Wontdothatagain]

but we have to make a risk assement of the venue, so a private wedding in someones garden i would have no hesitation in run a sub main from the house and keeping it (pme)

I think that is the most stupid and dangerous quote that i have ever seen on this forum.

 

[bernardgreen]

look guys you can give all the senarios you want and i aint got time to argue with you all because i am going to get p****d.

With that attitude you might end up with one of more of the guests being frissed. ( frizzled ) and your bank account emptied.

If the tea urn hot tap is only a few volts above wet ground potential then a fatal electric shock is un-likely but a person running boiling water from the tap might react to the mild electric shock and end with with serious scalding.

And it matters not that the party is in a private garden. If there is an electricity related incident the person who installed the power is responsible.

If one of your guests is injured due to your negligence and / or ignorance and is off work then it is quite possible you will have to pay compensation to the person for loss of wages and maybe their employer as well ( for loss of the employee's skills while off sick ). If that person has income protection insurance that pays him while off sick then that insurance company will come after you to recover the money they pay the injured person.