Design Flashcards
What is the minimum lux level for escape routes in public environments?
1 lux
What is a maintained light?
A light that is used as a normal light and emergency lighting
What is a non-maintained light?
A light that is not used, unless in an emergency
What areas require emergency lighting?
Hallways of a HMO
Inside a public room
Escape stair cases
Changing height/direction of an emergency escape route
During an emergency, what lux must stairwells be?
A minimum of 2 lux
What is a distribution circuit?
From transformer to consumer unit
What is a final circuit?
From consumer unit to accessory
What is basic protection?
Covering live parts
What is fault protection?
Earthing, bonding and ADS
What is additional protection?
RCD’s, RCBO’s
What is the max ZE for a TT system?
21 ohms/ 200 ohms is unstable and needs RCD protection of 1667 mA
What is the max ZE of a TN-S system?
0.8 ohms
What is the max ZE of a TN-C-S system?
0.35 ohms
What is the earth in a TT system?
An earth electrode in the ground
What is the earth in a TN-S system?
In an old installation - lead sheathing
In a new installation - steel wired armouring
What is the earth in a TN-C-S system?
A connected neutral wire
What needs to be on all bonded extraneous and conductive live parts?
A BS 951 tag (safety electrical connection, do not remove)
What is overcurrent?
A current exceeding the rated value. For conductors the rated value is the ccc
What is an example of overcurrent?
Using a 45A cooker on a 20A breaker
What is overload?
An overcurrent occurring in an electrically sound circuit
What is short circuit?
Ab overcurrent resulting from a fault of negligible Impedance between live conductors with a potential difference under boreal operating conditions
What is an earth fault?
A current occurring between a live conductor and an exposed-conductive part or protective conductor
What is an example of overload?
A motor-driven conveyor having an additional load to be moved
What colour is a BS 3036 5A fuse? (Re-wireable)
White
What colour is a BS 3036 15A fuse? (Re-wireable)
Blue
What colour is a BS 3036 30A fuse? (Re-wireable)
Red
What is ADS used for?
Protection against the effects of earth fault current
What are the tests for 3-phase safe isolation?
N/L¹ N/L² N/L³
E/L¹ L/R² L/R³
L¹/L² L¹/L³ L³/L²
N/E
