I live in U.S., doing design work in Qatar but am a little mystified by differences between Qatar (Kahramaa)/British Standard requirements and NEC/Nema/ansi/UL-land design.
1) Anyone have experience with RCBO requirements? Is there a reference book which explains this in more detail than the BS...
Depends upon the context.
IEEE publishes are series of "standards" for various topics of facilities engineering - the series is known as the "Color Books."
http://standards.ieee.org/colorbooks/sampler/shop.html
UL also publishes a couple of books which tend to be known by their colors, e.g...
I have a contractor who has located a junction box within 4'6" of the front of my switchgear - contrary to the drawings. According to NEC 110.34 (A), condition 2 for 7200 volts to ground, we need 5'0".
What I would like to do is cover or coat the box with insulation to make it Condition 1...
Just take a voltage across each input of the bus differential relay (if it's for example a GE SVD bus relay). Any voltage substantially higher than zero (if your bus has tested out) will tell you if you have a failing CT - just maybe not which one.
Is there a place I can get an IEC standard impedance for a say, 20 MVA, 110 KV-11 KV transformer, 50 Hz, for use in the Middle East, without laying down 3500 bucks for the IEC transformer collection? Thanks.
On 208 or 240 volt systems when the transformer is under 150 KVA, non-fused should be fine. On nearly every 480 volt system, the interrupting current is over 10kA, so fused should be used unless it's protected by an upstream dedicated fuse sized to protect that switch/circuit.
Grounding the system will reduce the possibility of a line-line fault going through their ground system. While a fault will trip a breaker off line, and thus shut down a piece of equipment or the System! Maintenance is much easier with a grounded system. Trying to find the fault when the...
Another way to look at it is a switchboard is floor-mounted, while a panelboard is wall-mounted (although very large ones might reach the floor). One other criteria that we use is up to 1200 amps - panelboard - 1600 amp and above is a switchboard.
Look at the SFPE handbook - there is a calculation procedure in there that should give you just what you need for audible alarm coverage. The calculation is fairly straightforward - adding & subtracting dB based on the construction.
It's not listed for the application - I wouldn't do it. That starter is sized for a motor circuit, which is sized under different code and UL rules. I don't think it should be done.
