External 3 phase sockets (pme supply)

[elecreturn]

I have been asked to wire in 4x 16a 3p+N+e rcd protected sockets (rcd's fitted within each socket), to be externally mounted in a car park to connect in refrigerated vans overnight, to be used by competent operatives. My main question is the earthing arrangement. I'm sure I should run the armoured cable, earthed at the dist board (from within the building) to each socket, then at the socket don't connect the supply earth into the earth terminal, but run an earth from the socket to a local earth rod. Is this the right way as I'm sure it is. Also can I use one earth rod and loop the earths or fit one earth rod for each outlet?
The supply into the building is pme
cheers in advance!

 

[cliffed]

I have been asked to wire in 4x 16a 3p+N+e rcd protected sockets (rcd's fitted within each socket), to be externally mounted in a car park to connect in refrigerated vans overnight, to be used by competent operatives. My main question is the earthing arrangement. I'm sure I should run the armoured cable, earthed at the dist board (from within the building) to each socket, then at the socket don't connect the supply earth into the earth terminal, but run an earth from the socket to a local earth rod. Is this the right way as I'm sure it is. Also can I use one earth rod and loop the earths or fit one earth rod for each outlet?
The supply into the building is pme
cheers in advance!

Tricky one really,can,t see a problem just using the pme earth point,sockets are protected & no main bonding requirements.

 

[Darkwood]

Are the vehicles all in one van/freezer units -ie... always sitting on 4 wheels or the trailer type that can be unhitched and sat on drop stands?

There is scope here to treat it as a metal building if the latter Ill let this one bat about for a decisive answer as not every situe' is covered in the reg's and can mean finding a solution to suit using the reg's we know.

 

[davesparks]

A couple of thoughts.
You can get ready made external boxes with 4 sockets and Protective devices in them, that way you would only need one supply.

An internal means of isolation or a means of locking the sockets off externally when not in use would be a good idea to avoid unwanted use of the sockets.

 

[Rockingit]

The BGB cannot stipulate for every instance, ffs it's big enough as it is! But, whenever it references a connection to something 'mobile', be it a boat, or caravan or car or whatever it always suggests using a TT solution so I'd have thought that's where a correct method would lay.

I would: common supply to a plastic box 4 x cpd 4 x outlet, earth the armour from supply end, divorce at the other, internal iso as well to stop improper use.

 

[elecreturn]

Are the vehicles all in one van/freezer units -ie... always sitting on 4 wheels or the trailer type that can be unhitched and sat on drop stands?

There is scope here to treat it as a metal building if the latter Ill let this one bat about for a decisive answer as not every situe' is covered in the reg's and can mean finding a solution to suit using the reg's we know.

Thanks for all replies so far

Vans don't have trailers so will be on tyres all the time....thick Ocado style delivery vans.

 

[elecreturn]

A couple of thoughts.
You can get ready made external boxes with 4 sockets and Protective devices in them, that way you would only need one supply.

An internal means of isolation or a means of locking the sockets off externally when not in use would be a good idea to avoid unwanted use of the sockets.

Tried that one...the client wants each van to have its own space and its own outlet.
The proposed sockets will have provision to fit a lock but the car park is secured to the client's use only.

 

[Engineer54]

Not really sure what the problem is here? We are not talking about a situation where human or animal accommodation is involved, or where highly combustible feul is stored, but a vehicle with a refrigeration unit, that is kept in operation overnight in a secured private car park....

So someone tell me why a PME supplied socket outlet can't be used, without messing around trying to provide a TT system??

 

[elecreturn]

Not really sure what the problem is here? We are not talking about a situation where human or animal accommodation is involved, or where highly combustible feul is stored, but a vehicle with a refrigeration unit, that is kept in operation overnight in a secured private car park....

So someone tell me why a PME supplied socket outlet can't be used, without messing around trying to provide a TT system??

Thanks for reply

Im in agreement, I'd sooner not mess about trying to TT it, driving in rods, extra tests etc. thing is we all interpret the regs differently especially in the absence of a definitive answer. I'd be happy to just fit the sockets as I would with a normal tn-s supply, I just want to make sure I wasn't going to do something completely and obviously wrong.

 

[Rockingit]

Not really sure what the problem is here? We are not talking about a situation where human or animal accommodation is involved, or where highly combustible feul is stored, but a vehicle with a refrigeration unit, that is kept in operation overnight in a secured private car park....

So someone tell me why a PME supplied socket outlet can't be used, without messing around trying to provide a TT system??

Well, assuming that we classify this as a Mobile or Transportable Unit (the definitions of which do seem to fit this, btw) then 717.411.4 says that you cannot use PME except under skilled persons / assessment each time.

 

[Engineer54]

Well, assuming that we classify this as a Mobile or Transportable Unit (the definitions of which do seem to fit this, btw) then 717.411.4 says that you cannot use PME except under skilled persons / assessment each time.

It's a refrigerated Van/Lorry were talking about here, ...Not a Mobile ''home'', or transportable ''caravan'', which the regulations you quote are in all probability, referring too!! (I don't have my BGB to hand)

Whatever way you want to look at it, i would assess each and every time that these refrigerated vans, parked up over night in a secure parking area, is just fine and dandy to be supplied by whatever functional supply earthing system is available in my book!! lol!!

 

[jamie-spark]

Well, assuming that we classify this as a Mobile or Transportable Unit (the definitions of which do seem to fit this, btw) then 717.411.4 says that you cannot use PME except under skilled persons / assessment each time.

Agreed Gn7 states 717
Units are either
1. Of mobile type eg vehicles ( self propelled or towed)
2. Of the transportable type eg containers or cabins

 

[Engineer54]

Agreed Gn7 states 717
Units are either
1. Of mobile type eg vehicles ( self propelled or towed)
2. Of the transportable type eg containers or cabins

Jesus..... Think about it, just for a second or two, ....These van's/lorries will only be connected to a mains power supply during periods of non usage ,...eg, overnight in a private secure company parking area. During normal working, these refrigerated vehicles are self contained, running off battery/alternator....

PME/TNC-S restrictions generally relate to habitable mobile vehicles, shore supplies to boats, and public usage service filling stations....

 

[Rockingit]

Jesus..... Think about it, just for a second or two, ....These van's/lorries will only be connected to a mains power supply during periods of non usage ,...eg, overnight in a private secure company parking area. During normal working, these refrigerated vehicles are self contained, running off battery/alternator....

PME/TNC-S restrictions generally relate to habitable mobile vehicles, shore supplies to boats, and public usage service filling stations....

I'm 'morally' in full agreement with you, but it cannot be denied that the wording in the BGB is (for a change!) fairly clear on this. It's actually made me wonder about all the times I've been asleep in my bunk on a tour-bus whilst it's been parked up next to a venue on 'plug in', as well. As I can tell you now, when a bus driver see's a 32A outlet he's not in the slightest bit bothered about just plugging up into it!

 

[wozz]

Interesting debate chaps, I've seen many of these put in and usually they are not TT, I always thought it was a bit close to a caravan but never looked into it much further as I was never involved with the installation myself.