3 Phase supply at race tracks

[cater_racer]

I was at silverstone last week and the outer paddock only had 4 pin 415v sockets. I needed to plug in my camper van, fortunatley the people next door had a 4 pin plug which lead off into three tails of 'normal' 16A camper connections.

How have they wired this? is the 4th pin the ground? and they have gone across two phases for live and neutral? or have they used the forth (larger pin ) as Neutral and one phase as live? With no earth?

I'd be greatful for ideas.

 

[Nigel Goodwin]

The fourth pin MUST be neutral - you get 415V between phases, and 240V between neutral and any one of the phases.

 

[cater_racer]

Thanks Nigel, as I thought, must be without a earth.

 

[Hero999]

Do you have a picture or either the outlet or the plug?

I don't think I've seen a 3P+N socket before. They're probably three phase no neutral, the fourth pin is earth, if one pin is slightly longer than the others then it's certainly earth.

You might be able to get away with using it as a neutral (if there is no RCD) but it wouldn't be safe or legal.

There should be an earth anyway for safety reasons, unless it's a neutral (like Nigel said) and each caravan is earthed via a large metal spike burried in the ground.

The only legal and safe way is to use a transformer to convert two phases to 230V. You can buy control panel transformers for this kind of thing; RS, Farnel and Rapid all sell them.

How much power do you need?

 

[cater_racer]

Thanks Hero999 the forth pin is fatter and longer, it's probably a Neutral, but could be earth. But the chap next door must have used it as Neutral. I only needed about 2 Kw to run the kettle and mircrowave so probably pulled about 8 amps max. The normal blue plug is 16A and I'm pretty sure the red 4 pin was a 32A 3 phase connector. No RCD trip in the way so it worked. They take a dim view of you burying spikes in the paddock, so it was probably illegal, and it worked

But I was only there for 24 hours, next week Donnington, I'll look around with a bit more interest. Thanks.

 

[Nigel Goodwin]

A quick google finds:

Plugs are available in 2P+E (single phase), 3P+E (3 phase no neutral), and 3P+N+E (three phase with neutral). Current ratings available are 16 A, 32 A, 63 A, 125 A and 200 A.

So presumably earth and not neutral (which are the same thing anyway), but I wonder how 'allowed' it is to tap a single phase like that?.

 

[Hero999]

To do it legally you need a 2kVA transformer, a heavy and bulky item.

Both RS and Farnell sell them.

Block | Transformers | Transformers | Din-Rail, Panel, Wall Mounting Transformers | Multi Output - DIN, Rail and Panel Mounting
BLOCK|STEU2000/23|TRANSFORMER, 2KVA, 230/400V, 2 | Farnell United Kingdom

 

[RODALCO]

Plugs and sockets for 3 phase and neutral (4pin) and earth (5pin) do exist in Europe and Australia and New Zealand.

Although most common 3 phase and earth are used.

 

[tcmtech]

Around here many public buildings have three phase outlets that are the same sockets as the 4 prong stove type outlets used on 120/240 single phase.
The three phase is typically 120/208 or 240 only with the fourth prong working both as ground and common line. While in single phase the third leg is common and the odd shaped fourth prong is ground.

NEC says this is illegal but I have seen it every place that is a public building and in many locations across the country as well.
Our state fair grounds buildings and a number of local public buildings have both the 120/240 single phase and 120/208 three phase coming out of the same style of sockets. Often with both voltages available in the same room!
Plug into one and your three phase stuff doesn't work. Plug into the other and your single phase stuff either gets 208 or 240 volts on the 120 connections and you have no ground lines actually connecting to ground.