Exhibition display cabinets

[frank999]

Hi

I have to make and supply 6 display cabinets on a public trade show stand (which we are building also).

The client wants LED strip lighting in each cabinet (about a mt p/cabinet- so about 5w) can a spark kindly advise regarding Regs if it is OK to use simple bell wire from all 6 cabinets going back to one multi out (12v) LED power supply, input is 240v. The bell wire will be trailed under the stand floor.
My understanding (of Exhibition halls electrics - a special location) is that it is not possible ... even though 12v, if that is connected to a device which in turn is connected to 240v ... then it makes it a no no. Could any one verify that.

Seems daft ruling - or maybe I am wrong and its passable.

Thanks.

 

[PrenticeBoyofDerry]

The cable will need to be rated sufficiently to handle the loading/demand current and be rated equal or greater than the protective device serving the circuit.
Current carrying capacity of cables could vary, defending on the method of installation and voltage drop.
The cable most also rated in the correct voltage band, so if you are using 230V, the cable must be in the respective voltage band.

 

[stillp]

The cable will also need to be capable of handling the mechanical stress. "trailed under the stand floor" might not be within the capability of bell wire. Why do you want to use bell wire anyway?

 

[frank999]

Hi thanks, wanted something flat - and its used for wiring between LED strips.
A 1mm BS6004 cable from Power supply to cabinet, which has a rating exceeding the 12v 5w draw from the cabinet lighting.
As I am not an electrician qualified to lay cables (even though only 12v 5w) - if I RCD protected the circuit (of the 240v cable feeding the powersupply) would I then be legal to do so.

 

[PrenticeBoyofDerry]

The cable needs to be suitable to carry 240V, having RCD protection does not exclude that requirement.

 

[Taylortwocities]

Methinks you should aquaint yourself with Section 711 of BS7671 with particular attention given to the paras relating to Wiring Systems.
IIRC wiring cables must have minimum csa of 1.5mm²

 

[flameport]

Separate LED power supply for each cabinet, fixed inside/underneath and fully enclosed so it can't be touched.
1.5mm flex from that, suitably attached to the cabinet with strain relief, normal mains plug on the end with a 1A fuse.
Repeat for each cabinet.

Each cabinet can then be individually tested and the appropriate documentation produced, which will inevitably be required by whoever is organising the event.

On another point, 5W of LEDs for a display cabinet seems rather low, unless these things will be tiny? Roughly equivalent to a single 50W halogen spot.

 

[bernardgreen]

In years gone by the electricians employed by exhibition venues used to be very militant about who could do what with the electrics on the stands. Even wiring a 13 amp plug onto a piece of equipment being exhibited had to be done in the back out of sight or risk the supply to the stand "developing a fault". I suspect ( hope ) that is no longer the case but maybe worth checking on any demarcations between what exhibitor's staff can do and what only the venue's electricians can do.

 

[frank999]

Flameport - thank you for your comment, yes we will have each cabinet PAT tested - is this guidance written down anywhere official that I can refer to ?

1 amp fuses, would a 3 amp be passable ?

We will be using crude LED rope light (as requested by client), cut as required and wired together in the cabinet, probably about 1mt in length, which draws 4.8w.

 

[Taylortwocities]

Section 711 of BS7671

 

[JohnW2]

I'm a bit confused by this thread. AFAICS, the OP has asked specifically about wiring on the ELV side of 12V power supplies, but many of the responses seem to be assuming that we are talking about LV wiring. Am I missing something?

Kind Regards, John

 

[Taylortwocities]

IIRC, the "book" section 711 talks about wiring systems being a minumum csa of 1.5mm². There is no distinction made as to if this size being specific for LV or for ELV wiring.

 

[JohnW2]

IIRC, the "book" section 711 talks about wiring systems being a minumum csa of 1.5mm². There is no distinction made as to if this size being specific for LV or for ELV wiring.

That may be true (I don't currently have my book to hand!), but that doesn't alter the fact that a lot of the discussion here seems to have been about the need for cable with "230 rating" and RCD protection, whereas the question was about the ELV wiring.

Kind Regards, John

 

[frank999]

I spend a lot of time in Trade show venues, admitedly some venues are more strict than others, but you must always be prepared for a 'visit' during build up.
On the larger 'space only' stands, when experienced stand contractors wheel the large parts of the stand in - I see 'Weiland' type connectors on 3 core white flex cable (the type of cable you find on appliances) dangling out of the base of each part, they connect this to similar Wieland's coming up out of a hole in the stand floor (this is not to be confused with the mains coming up from the venues duct, and the floor is the temporary floor of the stand, not the venue floor), these no doubt running under the floor, I assume back to a 13amp socket supply, which is connected to the stands mains isolator - which is in turn connected via armoured cable and then disappears down a duct - in the actual floor venue.

Flameport seems to know whats required, no mention of Weilands there, I have discussed this with one or two big venues - and they all say Weilands are a big no no.

At present we are paying a lot of money in venue supplied 500w 13a sockets, to simply power very low consumption LED lit cabinets and lights spread over a stand approx 10mt's in length ... how much cheaper it would be to be able to connect all these items in parrallel back to one point feeding the 12v, then plug that into a 13amp socket (as I assume others are doing with Weilands), at present its almost one mains 500w 13a socket to feed one cabinet/light - seems daft, hopefully that explains the point of the thread better.

Is there a cable length limit ?, I understand 2mt is for four way extensions plugged into venue supplied 13a sockets, how about PAT tested display cabinets ?

 

[stillp]

In years gone by the electricians employed by exhibition venues used to be very militant about who could do what with the electrics on the stands. Even wiring a 13 amp plug onto a piece of equipment being exhibited had to be done in the back out of sight or risk the supply to the stand "developing a fault". I suspect ( hope ) that is no longer the case but maybe worth checking on any demarcations between what exhibitor's staff can do and what only the venue's electricians can do.

Many years ago my company had a stand at Electrex, with 8 panels that needed about 50W each, run off two 4-way extension leads plugged into the very expensive NEC-supplied 13A sockets. Sometime between the close of the first day and start of the second, both 4-way adapters disappeared.