I am looking to be able to produce a numbering system for structured wiring voice/data outlets, such that when I produce the number on the drawing via say a data point block, the number automatically increments by one for the next block inserted.
Is there any routine for doing this?
Many...
lyledunn,
The Electricity at Work Regulations should prevent someone from accessing live busbars. In the MoD we used to operate a Permit to Work System where any person working downstraem of a UPS had to be issued with a Permit to Work. The Authorised Person is responsible for writing a safety...
Lyledunn,
To provide shock protection on the supply side of the UPS I always use RCD's. Whilst this tends to negate the principle of the UPS, if you correctly design the circuits for earth leakage in equipment i.e. limit the earth leakage to within say 10mA via, dedicated circuits I have not...
I would be interested to know if the US fire alarm system regulations require a minimum noise levels.
In the UK the requirement is 65dB minimum in any normally occupied room or 5dB above ambient noise levels. For sleeping accommodation it is 75dB minimum.
We are also required to provide a...
In the UK we use single phase 220V supplies. Three phase suppies are rated at 440V.
I know in the American continent it is common to use bi-phase supplies from a 120V ph-n system to achieve 220Vac. This is a method of wiring not considered acceptable in the UK.
Over the years I have used UK...
Lyledunn,
Basically with a 3 wire system the ground current return to the source (the transformer or generator) is via the phase-earth conductor and earth rod mat i.e. in this case the earth loop impedance includes the 5 ohm resistance of the mat plus the phase-earth conductor impedance.
For a...
Just an iteresting additional point on PVC/SWA cables - it has become practice in the UK now to replace the old 11kV paper/lead cables with PVC/SWA. The advantage of the paper/lead cable was that it acted as an auxiliary electrode and reduced the overall earth impedance at the substation. As the...
We tend to test general fixed electrical installations every 5 years.
If the installations are in hazardous areas this reduces to 6 months or 12 months depending on the hazardous area classification.
Do UK local authorities or Insurance Companies make any recommendations?
Lyledunn
I spend a little time working in Eastern Europe and South America. The idea of testing electrical installations is very little understood, and I generally have to teach people everywhere I go. For example RCD tests, and earth loop tests are not often carried out nor is test equipment...
I think that basically for say motors and generators at altitude, as the air is thinner or less dense it's ability to remove heat decreases. It is the mass flow rate of air across say motor or generator windings that is important rather than the volume flow rate.
General rule of thumb is for cables up to about 120mm2 the cross sectional area is sufficient to be used as the earth conductor. Over that then you may have to run a separate CPC. I sometimes run a separate CPC if you are using a large MCCB (without time graded RCD protection) where you cannot...
