Is it a regular occurance, that an Electrician in the UK, would come into contact with 415V, Phase-Phase-Phase?.
We use over here, 400V, between all phases,
but, what I would like to ask, is, is your technique, any different from working on 230 to Earth, with the risk of inter-Phase Flash-over?.
Your thoughts please-

Trumpy,

I deal with three phase ( red phase 230v, yellow phase 230v, blue phase 230v )on a day to day basis.

I have only had one flashover between phases and that was not pleasant, it was caused by my then apprentice bringing in the wrong isolator (he was a third year, so in theory he should have known his a b c).

Working on three phase (415 or it is now known 440 or 400v ) is you would use the same caution and respect that you would for 230v single phase.

about one of the only things i have noticed within the time i have been an electrician is that the bonding of the enclosures are a lot better than ordinary single phase panel boards.

if there is anything else you want to know, just ask.

John H

Well, I hope you don't mean "in contact" literally!

I mostly deal with residential, which as you know is single phase 240V here. I work with 240/415V 3-ph systems in some small commercial jobs, although these places generally have only 1-ph 240V loads, so there are no 415V circuits beyond the distribution panel. There is, of course, the very real chance that different phases have been brought into close proximity, or even into the same switch box. I've seen some DIY botch-jobs that have left a twin light switch liie this, and I wonder whether the person who "threw" those wires into rthe box realized that he was dealing with 415V between them.

Do you regularly used fused test probes in NZ when taking voltage measurements, to minimize the risk of an explosive arc if the meter was, say, set on a current range by mistake?

Paul,

we dont actually come into contact, ouch ! (i have only once, and it cost me a lot of time off)

We are sometimes called into a lot of commercial properties to fix lights and the such like and most of the time the identification of circuits and phases is not done, so you end up removing the plates from switch gear and finding a bunch of red cables and the theory should be that that set up is red phase 230v.
then when you start testing you get two different phases and sometimes three.

There are requiremnts within the regulations over here to identify each circuit and to what breaker it is fed and from what phase,

IE R1/DB3/LT1
Red phase / Distribution Board 1 / LighT number 1.

if the R changes to Y or B you automatically know you have three phase within, (also by the warning notice, Danger 415 Between Switches, that should also be placed on or about the switch gear.

Bye for now. John H

John wrote:

>the warning notice, Danger 415 Between Switches

Get real, what are the 415V going to do to you? Jump out of the switch and bite you? Geez, those British volts must be something out of the ordinary!

Proper identification of the circuits is a really good thing. Are the circuits in England identified in real life or just in the regulations? It's all too often neglected in Sweden. (New offices are good, old homes a disaster) Even experienced electricians sometimes miss that single pole breakers or diazed fuses in fact form a 3-phase group. The diazed panels are a real danger, in my humble opionion: There are three rows of fuses in the box, corresponding to the three phase busses. A poly-phase block consist of two or three fuses in a column. If there is a circuit number above the top fuse only, it tells you that it's a 3-phase circuit. The trouble begins when the box is orginally used (or identified) for single-phase circuits with a number above each fuse, but later 3-phase circuits are added.

All of a sudden the list next to the box goes:

1.) Lights, first floor
2.) Sockets, first floor
3.) Kitchen sockets, 3-phase
4.) Sockets second floor
5.) Disused
6.) Dishwasher, 3-phase
7.) Garage
8.) Basement
9.) Fridge, 3-phase

Not everybody is kind enough to write 3-phase after #3, 6 and 9... Worse, the list often gets lost. I've even seen a panel where either the list was wrong or a 3-phase block actually zig-zaged in the panel.

[This message has been edited by C-H (edited 03-23-2003).]

The warning notices go along with my comments elsewhere about the IEE's views on anything over 250V.

If you go into a restroom here and it has two or more hot-air hand dryers, then you may well see a similar sign "Danger: 415V between" with arrows. That's a requirement if the dryers are on different phases and within arms reach of each other.

John,
The identification of circuits is often sadly lacking in the residential and small commercial environments in which I work. I often spend the first hour just tracing which fuse/MCB feeds what.

I did once see a medium sized shop, full of freezers, lighted display cabinets, and so on, in which somebody had painted the fronts of the sockets red, yellow, and blue!

Paul asks:


So the buzz for awhile has been “IEC 1010-1 installation/overvoltage categories” ratings for multimeters. It may be more of a concern for those dealing in maintenance work.

Is this an issue for anyone here?

Paul,
To answer you question, regarding Fused Test leads, I've used them since I first started in this Electrical game, makes sense, doesn't it?.
But, it is really only Industrial Tech's,Faultsmen and the odd Sparkie that is in the know, that use these Leads, over here.
I have 1000V, 500mA, leads myself, how about you?.

After doing some fatal damage to a rather nice piece of test equipment when i was an appretice (many years ago) ALL my test leads are fused at 500mA,

In regarg to signage i have to agree will Paul,

most of the time in large commercial / industrial you will find the signage is usually there, but sometimes (ok most of the time) another sparky has come in and done a bit here and a bit there, added an otlet there, taken a supply from hear, wired another piece of equipment from another supply and low and behold what is written in the panel is not what is installed in the building !!

As we specialise within the liesure industry, Bars, nightclubs etc, they are the worst !!

its like ` lets see who can do this the cheapest` and when it goes wrong, then they call the proffessionals in!!

C H, if 415 jumped out at me, i think i should have to go and seek proffessional advice from my local shrink !!!

But on another topic, slightly, i have had a 100a Three Phase isolator explode at me, we contacted the manufucturer and they said it was a design fault !! took a few years of me i can tell you. !

John H

John H,
I agree with you whole-heartedly, regarding your comments on Panel labelling!.
Over here, the quality of labelling varies from poor to down right negligent.

i can understand the european system and far for north american system most home are wired for 120/240 volts ( most common ) and some case 120/208 volts also but in commercal and industrail system go much higher we have 277/480 volts system and all the panel boards are marked clear for waring the high voltages and genrally take a extra step more with 277/480 system and if you want to know if i got wire zapped with it and yeah it do pretty messy with 480 v it can do some damge fast if you dont look out but i am not sure what you guy do at U.K. and N.Z. system do but i do remeber french system very well it is very simuair to U.K. system .


for flash over on higher voltage it is very simuaur with 400/415 volts you guys metion

merci marc

Gidday Marc,
You mention 277/480VAC, where is this used, if I may ask a question?.
With regard to "Flashover", this term is really only used with HV(1000V+)systems as the voltage only jumps between phases over this voltage.
With respect to an arc-flash, however(this is what happens when 2 phases or a phase and Neutral) hit one another, wether it be because of wind or a screw-driver of a person wiring a Panel, the results are not the same.
Hope this helps.

thanks trumpy :

now i get your picture about flashover but some case we do get flashover even in very high humity conditons but not the same as "bolt falut" ( driect short) the last time i see the flash over was few week ago i was working on breaker and the humity was sooo high in one room like steam vapor it was pretty spooky when i see alot of mositure on the wall i say to myself "oh oh merde( a famous four letter word i cant print here)!!!" and i can actally hear the electic crackle (noise) and smell it then turn off the main power source at the main breaker with insluated gloves and hot stick to push breaker off and check the damage and alot of sweat on wire can flashover btw this is a big 480 volts 4500 amp switchborad!! that was amazing to see the flashover for this size and lucky did not blew up


thanks for explain trumpy

ps some very high voltage system can flash over with power surge too

opps i forgot to add this one the 277/480 volts are common on commercal and industrail systems but never for homes for safty reason

sorry about that

merci marc

Marc,
No worries, that's what I'm here for.
I can't believe that the humidity gets that bad where you are, is this true?.
So you use Hot-sticks and gloves, too!, join the club.
However, I am required to use them on 3.3kV,6.6kV,11kV,22kV and 33kV, for isolation and re-energising procedures.
Whopping great gloves and big Fibreglass telescopic Hot-sticks, the Higher voltages,22 and 33kV, give me the willies, when I am working with them!.

Trumpy,
Commercial power in the U.K., N.Z. etc. is all pretty standardized on 230/400V (or thereabouts) wye systems.

If you look back through tha threads though, you'll see that America has a multitude of systems that have been installed for commercial power. In addition to 120/208 and 277/480 wye systems, there are 240V delta, 480V delta, and the strange (from a non-U.S. perspective) 4-wire delta arrangement.

Canada has 347/600V wye as well, although I'm not sure how extensively it is used. (And I wonder whether these systems were derived from older 600V delta supplies?)
Maybe one of our members from the Great White North could add some details.

Paul,

I am so happy being only dependant on two sets of incoming supplies to our buildings over here,

good old 230v ac 100amp for (most) domestic
services.

and 400 v ac three phase (minimum) 100 amp per phase for commercial/small industrial service supplies.

I do find, on some of the larger contracts that i work on are in excess of 600a per phase on three phase, but the voltage is the same, and also on some larger domestic properties we have two phases comming in and sometimes three, depemdant on the load requirements,

The company is currently (sorry about the pun) working on a supply incomer of over 1000Amp per phase, this is going to be a fun installation to complete !!

trumpy:

the switchboard was located next to the boiler room and it was seprated by 1/2 meter thick cement wall and hevey fire door and i found where the hevey moisture came from it came thru the floor drain when the boiler go thru "blow down " and blew the steam up the floor grates and got too much condation when the electrical room exhaust fan cant remove all the vapor and that when the troble started grrrrrrrr i hate it and i did take no chance i knew that industal companie so i grab my hot stick and insluated gloves and trip the breaker manually it was hard one to trip but i got it and clean the concat and "charge springs" i mention that to my clinet that should use fuse insted of bloody expensive breaker it cost over 8.000 dollars for a piece of crap ( 8thousand dollars not a mistype) and it is my simple rule anytime want to fool around with 480 and higher just get hotstick and gloves and yes it is mantory for me work on meduim voltage system too 4160votls is most common i deal with it but i go higher as 15 kv as need the last highest one was 69 kv !!! that is spooky with that one

merci marc