Separation distances

Every person who stores explosives at a site must ensure that the relevant separation distance is maintained.

There are some exceptions to having to maintain separation distances:

• stores holding small quantities of explosive, ie 100 g or less
• stores holding 5 kg or less of a combination of shooters powders and model rocket motors
• stores holding 30 kg of shooters powders or less and/or up to 300 g of percussion caps, subject to certain conditions
• stores holding up to 200 detonators and 5 kg of water-based explosive and detonating cord; or 5 kg of water-based explosive or detonating cord, subject to certain conditions
• stores used by the police to keep no more than:
  • 4 kg of explosives for use for operational purposes including the training of dogs used for the detection of explosives
  • up to 30 kg of explosives kept for ordnance disposal or explosive means of entry and associated activities

provided that the explosives are stored in a safe and suitable place, with all due precautions for public safety.  More information on storing such explosives safely can be found in the Overarching guidance – Safety provisions (L150).

Where the explosives listed above are being kept with small arms ammunition, any separation distance required due to the presence of small arms ammunition will continue to apply.

Some other stores will not be subject to the separation distance requirements of the regulations. They are stores:

• other than those where HSE or ONR have granted a licence under regulation 13(6), where the only explosives being kept are desensitised explosives
• licensed by *HSE or ONR where the local authority has given its assent to the grant of the licence or where, in certain circumstances assent was not required for the grant of the licence
• controlled by the Ministry of Defence

Stores controlled by contractors on establishments owned or controlled by the Ministry of Defence are not exempt from the separation distance requirements.

Separation distances also apply to the storage of explosives even when a licence is not required and to stores operated by organisations which are exempt from the licensing requirements. This includes any stores operated by local authorities and police forces not detailed above.

*When they grant licences HSE and ONR will normally follow the distances given in Schedule 5 of ER2014 (or distances interpolated from these tables and the mathematical formulae which support them). HSE and ONR will normally follow the same approach to the aggregation hazard types and quantities of explosives required by Schedule 5. HSE and ONR may follow an alternative approach where it has been shown to provide an appropriate level of safety.

Buildings that are not normally occupied

Where the presence of people within a building on an explosives site is transient and that building would be a protected place of Class F, then for the purposes of applying separation distances, that building may be considered to be not normally occupied or unoccupied when it is being used by the people who are engaged in the site's explosives activities.

Examples of such unoccupied buildings could include toilets, changing rooms and switch-rooms. The requirements of regulation 26 of ER2014 would however mean that dutyholders will need to take account of the risks posed by such buildings in deciding where it might be appropriate to locate their stores and also have systems in place to ensure that appropriate measures have been taken to protect people using those facilities from the effects of a fire or explosion.

Buildings that are not on the explosives site and which are only occupied for a few minutes per day, such as:

• stores  which are only occupied whilst goods are removed or deposited; or
• stock sheds in farms only occupied for a few minutes per day to feed and water the stock.

should be treated as being occupied or inhabited and appropriate separation distances should be applied.

Building and construction type and the use of separation distance tables

* Tables - Guidance on Explosive Regulations 2014 lists all the tables referenced above.

Where a building contains more than one hazard type

Where a building contains a mixture of Hazard Types 1, 3 or 4, add the quantities of the various hazard types together and treat as the lowest numbered hazard type for example treat 20 kg of Hazard Type 1 plus 30 kg of Hazard Type 3 as 50 kg of Hazard Type 1.

Where a building contains a mixture of Hazard Types 2, 3 or 4, add the quantities of the various types together and treat as the lowest numbered hazard. For example, treat 50 kg of Hazard Type 2 and 50 kg of Hazard Type 4 as 100 kg of Hazard Type 2.

Where a building contains a mixture which includes Hazard Type 1 and 2 with or without other hazard types, add the quantities of the various hazard types together and treat as Hazard Type 1 or Hazard Type 2, whichever requires the larger separation distance.

Building construction type

Hazard Type 1 – Tables 1, 2, 3, 4, and 5