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Three Phase Power and Cross Phasing

#1 User is offline   frazer 

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Posted 28 August 2006 - 07:44 PM

Are there rules over whether or not having two or more phases on a lighting bar is allowed? I've been to various venues; some are relaxed about keeping phases apart and some are really strict. Is there a law governing it?

#2 User is offline   Andrew C 

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Posted 28 August 2006 - 07:56 PM

Tried searching? We've been here before!

No, the rules requiring a 2m separation lapsed with the 15th edition of the IEE wiring regulations. They lapsed due to the improved earthing standards.

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#3 User is offline   Rob_Beech 

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Posted 28 August 2006 - 07:56 PM

This is one for the search engine. The topic comes up too often. If you search around you should find the answer.

If you then have any specific questions either ressurect one of those threads or add it here.


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#4 User is offline   Tomo 

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Posted 28 August 2006 - 07:58 PM

This was a requirement in the 14th Edition regs (IIRC - may have been 13th)

However, the 16th (lastest) edition of the IEE electrical regulations has relaxed this requirement.

That said -
You may not be able to send two phases down the same multicore, as some places have chosen to use lower-rated insulation on the cable.

Other places have used the more expensive 500V rated cable, which eliminates the restriction.
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#5 User is offline   gareth 

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Posted 28 August 2006 - 10:15 PM

Do a forum search for "phase separation" - it's been well-covered on several occasions. Mods, perhaps this topic needs closing with a redirection to one of the many other existing threads?
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#6 User is offline   robloxley 

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Posted 28 August 2006 - 10:19 PM

But you will find the following paragraph of HSE guidance sheet "Electrical safety for entertainers INDG247" repeated many times as "law":

"Three-phase supplies
If lighting is connected to two or three phases of the electrical
supply, use separate dimmer cubicles on different phases to
avoid confusion. Only supply a single phase to any one boom."

To be fair this info sheet is aimed at pub & club performers rather than theatres, but it still gets quoted.

#7 User is offline   andystone 

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Posted 28 August 2006 - 10:25 PM

I think I'm right in saying that this is OK, but if you do it the bars (and anything else involved such as the patch) must have 415V warning labels on them.
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#8 User is offline   Dmills 

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Posted 29 August 2006 - 12:12 AM

View Postandystone, on 28 Aug 2006, 11:25 PM, said:

I think I'm right in saying that this is OK, but if you do it the bars (and anything else involved such as the patch) must have 415V warning labels on them.

I seem to recall that for most standard three phase installs the 415V labels are actually not REQUIRED as a close reading of the regs makes it clear that it is voltage to earth that requires labelling if greater then 240?

Now, I know that everyone puts 415V warning labels on three phase kit, and this is probably a reasonable thing to do, but I don't think it is actually required for compliance with BS7671?
IIRC one of the guidance notes mentions something about this?

Anyone have chapter and verse?

Moderation: This is only re-hashing material that has been covered several times. Please see the latter postings in this thread and several others. Also, the "power" forum is arguably a better place for this discussion. Therefore, this thread is now closed.

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