Which regulation says it is "forbidden to work live"? The SI can be viewed here: http://www.opsi.gov.uk/SI/si1989/Uksi_19890635_en_1.htm , I can't see where it says it is forbidden?
A Question about Wiring Colour Code Conventions
- Thread starter docboardman
- Start date
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H
holmslaw
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Why can't you ever accept you're wrong?
H
holmslaw
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How do you perform an earth loop impedence test without working live?
J
Johnmelad502
Testing Live. Permitted
Not explicitly.
All that the SI says about working live is this:
Work on or near live conductors
14. No person shall be engaged in any work activity on or so near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless-
(a) it is unreasonable in all the circumstances for it to be dead; and
(b) it is reasonable in all the circumstances for him to be at work on or near it while it is live; and
(c) suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury.
Nothing to say that testing is an exception.
And nothing to say that live working is forbidden, just that it has to be reasonable for you to do it.
P
Paul_C
Historical usage needs to be taken into account here, since the official IEE/BS7671 definition of "live" was changed. The old definition excluded a neutral or other earthed circuit conductor.
How do you figure gray for one of them? For a.c. circuits, the table of harmonized colors lists:
So I would say that if you really want to comply fully with those specifications, for a CTE 110V system both sides of the circuit should be brown (either as base colors or by sleeving blue as brown etc.).
Although it's been suggested that where brown/black/gray is used in a single-phase application with earth black should be sleeved green/yellow and gray sleeved blue, there isn't anything in BS7671 which actually requires that, just as there wasn't anything previously to say that blue had to be sleeved black and yellow sleeved green/yellow.
Just because red=brown, yellow=black, and blue=gray when matching up L1/L2/L3 for three phases doesn't automatically mean that you have to follow the same sequence when marking cores blue and green/yellow.
Frankly, the mess we're left with now is not surprising given the adoption of these harmonized colors. You can't really expect anything else when suddenly a phase color becomes a neutral and vice versa.
A single-phase feed to a sub-panel could be blue, black, and green/yellow. Is that a feed from phase C using the old colors, or from phase B with the new colors? Certainly it would be foolish to guess or assume, and testing and/or inspection would reveal which it is, but surely it has introduced unnecessary potential for confusion which we could well have done without?
Put simply, there was absolutely no need to change for the sake of some arbitrary new standard which serves us no better than our existing standard did. The "making everything the same across Europe" argument doesn't really hold up considering that (a) there are already a good few other differences in wiring and (b) buildings don't just get up and move to another country.
Re EAWR:
I'd say the "that danger may arise" clause is also very much open to interpretation. In other words, it isn't "must not work on or near any live conductor," it's "must not work on or near any live conductor in such as way as to give rise to danger," followed by the get-out clauses.
What constitutes danger is very much a subjective thing. Trying to squeeze your hand down the side of a live busbar to reach something when there isn't really enough clearance to do it would count. But not just putting your meter probes into a live panel to test something, as I've seen claimed by some.
H
holmslaw
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the phase conductor could be flagged / sleeved.
H
holmslaw
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H
holmslaw
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P
Paul_C
For a final circuit, yes. But a single-phase feed to a sub-distribution panel is permitted to use the matching phase color as an alternative. That exception goes right back to the days of red/white/blue phases.
H
holmslaw
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