26 Ammonium nitrate or ammonium nitrate mixed fertilizers containing residual process heat and having a temperature exceeding 130°F shall not be accepted for storage in a storage facility subject to these Regulations.
[...]
(6) Ammonium nitrate or ammonium nitrate mixed fertilizers in bags or bulk shall not be stored in contact with hot pipes, conduits, ducts, light bulbs or any other object with a surface temperature exceeding 100°F and should be stored at least 30 inches from such objects.
2 The principal properties and hazards of ammonium nitrate are as follows:
(a) ammonium nitrate is an oxidizing material that, at elevated temperatures, will support the combustion of materials such as wood, paper, fuel oil and sulphur; but self-sustaining burning reactions are not usually obtained unless more than one per cent of combustible material is present;
(b) ammonium nitrate undergoes thermal decomposition when heated to temperatures above about 150°F and, under certain conditions, some of which are mentioned below, this decomposition may become dangerous; because ammonium nitrate is usually stored in very large quantities, it has the potential to escalate an ordinary fire into an event approaching disaster proportions and for this reason, even a very small probability of occurrence cannot be ignored;
2 In these Regulations,
ordinary location means a location in which electrical equipment, under normal conditions of use, is not unduly exposed to damage from mechanical causes, excessive dust, moisture, extreme temperatures or corrosive, flammable or explosive atmospheres; (emplacement ordinaire)