FAQ

• + What is an MCB?

  MCB = MINIATURE CIRCUIT BREAKER

  Miniature Circuit Breakers are designed to protect people, cables and equipment from two main types of fault:
  
  (A)  Overloads: the gradual build-up of heat due to increasing current flowing through a circuit. A thermal device in the MCB detects this build-up and trips the MCB. The speed of this depends upon the severity of the overload and the tripping curve of the MCB as indicated below.

  (B)  Short circuit: sudden increases in current flowing through a circuit causes a magnetic device in the MCB to operate in a fraction of a second, protecting the installation and any persons in contact with the supply.
  The correct tripping curve of the MCB depends upon the type of equipment being protected. For example, florescent lighting and motors can cause an initial surge on start-up which may cause nuisance tripping with a B Curve MCB, therefore a C Curve MCB should be installed. If this is still inadequate then a D Curve should be selected. Our standard distro boxes are fitted with Type C.

• + What is an RCD?

  RCD = RESIDUAL CURRENT DEVICES 
  
  RCD’s work on the principle of a load being in balance – that is, the current on the Phase conductor is equal to that flowing out of the Neutral conductor. The Phase and Neutral cables in an RCD pass through a magnetic ring which detects any imbalance. If equal, the RCD remains operational, if imbalanced it causes the mechanism to trip. 
  
  Modular RCDs come in 2-pole and 4-pole versions. 2-pole versions are usually mounted in consumer units to protect a number of circuits at once. However, both 2-pole and 4-pole versions can be used separately as protection devices in enclosures.  
  
  There are two usual ways in which an imbalance of the load can occur:
  
  Indirect Contact: defined in the IEE Wiring Regulations as ‘contact of persons and livestock with exposed conductive part made live by a fault which may result in an electric shock e.g. the casing of an appliance or motor.

  Direct Contact: defined in the IEE Wiring Regulations as ‘contact of persons and livestock with live parts which may result in an electric shock.’ e.g. exposed damaged cable. In both cases RCDs should not be the only method of protection used - see BS7671 wiring regulations for further information. To provide all-round protection RCDs must be used in conjunction with suitable MCBs.

  RCDs are available in the following sensitivities:

  30mA the most popular sensitivity in the UK. In a shock, current flowing through body at 240V could be 80 to 240mA, depending on the resistance of the body in question. To ensure no harmful effects the RCD operates within 300mS at 30mA and 40mS at 150mA.

  100Ma may provide protection against electrocution. However, there is a likelihood that the earth fault current may be below the sensitivity of the RCD - increasingly likely if additional resistances to that of the human body are in the current path.300mA - provides protection against risk of fire only, not against electrocution in shock situations. A typical application is lighting circuits where risk of electric shock is small. Note, a current of <500mA flowing in a high resistance path is enough to cause metallic parts to potentially start a fire.

• + What is an RCBO?

  RCBO’s are a combination of an RCD and MCB in one unit. This enables both over-current protection and earth fault current protection to be provided by a single unit, which allows earth fault protection to be restricted to a single circuit, ensuring only the circuit with the fault is interrupted, limiting inconvenience tripping of many circuits.

  Two versions are available:

  1 module 1 pole version (17.5mm wide). Although the same width as a standard MCB it is twice the height. Ideal for use in consumer units where more control is required as to which circuits are protected by RCDs and which by RCBOs, as individual circuits can be protected as opposed to groups of circuits in a standard split-load consumer unit.

  Standard 2 Module RCBO (35mm wide). These usually switch both the live and the neutral connections

• + How much power consumption?

  The Socket Calculator has been brought to you by Electrical Safety First.

  For more safety information visit http://www.electricalsafetyfirst.org.uk

• + I'm looking for a custom built solution. Can you provide these?
  We can supply custom made power distribution boxes in many different configurations, these are available in rubber, thermoplastic, polypropylene, or steel frame. We can also have cables made to order,IEC - PowerCon - 13A or 15A.
  Please call or send your requirements to our technical departments email: enquiries@distributionzone.com
• + What areas do you deliver to?
  We can deliver to anywhere in mainland UK and Islands using DPD or others. We also deliver further afield including to the EU, Australia, NZ, Middle East, Africa and the USA. We have FedEx and DHL accounts, anywhere is possible.
• + Can you deliver same day?
  We use an established local courier company who can guarantee same day delivery throughtout the UK, subject to delivery charges. If your order is urgent and the products you require are in stock, we can arrange for same day delivery. 
  
  Please note, this is also subject to availability and the time that the request is made; if the request comes too late in the day, it may not be possible to arrange for same day delivery. 
• + I'm local to you – can I collect from you?
  We don’t mind if you want to collect your order from us, we’ll try to be as flexible as possible. Please give us plenty of time to pick your order though, please also let us know prior to arriving.
• + What about project pricing?
  We love to work on projects large or small however, we can often offer special pricing on the larger opportunities. Call us with your requirements - we would expect to be able offer you the most competitive of quotations.
• + After-sales support
  Despite our best efforts there is occasionally a need for after-sales assistance. Rest assured that we will always provide prompt and helpful support for any problems you may encounter. Please contact us if you require any further information.
• + Why buy from us?
  We have a direct relationship with our manufacturers, all based in the EU. This is your guarantee of a great product, sourced from a great company. Our mission; to bring you the very best products at the most competitive prices, from the very best companies in their chosen fields.