Guidance for Entry into Substations and Switchrooms

This informal CPD article Guidance for Entry into Substations and Switchrooms was provided by Horizon Engineering Solutions, established in 2015 to fill the gaps in the marketplace within Northern Ireland for the provision of specialist Electrical and Mechanical Engineering support services to major industrial clients.

An untrained or inexperienced person, which could include members of the public, children, vandals, client employees, apprentices, non- electrical trades persons and in some cases client management could have little or no conception of the many hazards which could exist within a substation or switch room. It is therefore essential that all substations and switch rooms are secured to prevent any unauthorized entry.

Even for those trained and experienced in the hazards which may exist it is still vitally important that they carry out safety checks in a methodical manner before entering any substation or switch room.

The Role of the Authorised or Competent Person

As an Authorised or Competent Person, you must not enter or allow anyone else to enter a substation or switch room until you are satisfied that it is safe to do so. You must not endanger yourself or endanger anyone else who may be under your supervision or who will be carrying out work under a Permit to Work. 

The pre-Entry and Entry Safety checks highlighted in this article should be considered as the minimum required. Depending on site conditions additional safety checks may be required and these need to be documented on your Method Statement and Risk Assessments for the work which is going to be carried out. This should also include amending and adding to your Safety Checklist as required.

Even if you are very familiar with the substation or switch room it is essential that you carry out safety checks before you enter them. You should not assume that it will be safe to enter without checking.

Things can change! So be prepared!

When planning your work ensure that your Method Statement and Risk Assessment, or Standard Operating Procedure (SOP) identifies:

• All the potential Hazards which you may encounter
• The control measures which need to be put place to either eliminate or reduce the Risks
• The PPE, tools and equipment which will be required to carry out the work safely

It is also recommended that special attention is paid to the presence of

• Fire Protection Gas Suppression systems
• Asbestos
• Gas
• Vermin
• Ingress of water
• Mineral Oil, MIDEL or
• SF6 Gas and its decomposition products

Pre-Entry Procedure

Before you approach a substation or switch room check that the Fire Detection and Alarm System is indicating normal healthy conditions. When approaching a substation or switch room the most obvious and most important thing you must do is to verify that you are at the right substation or switch room.

Mistakes have been made when people have entered the wrong substation or switch room to carry out work. To verify your location, always use up to date site drawings and information, and check the external identification and warning signage usually found on the door of the substation or switch room or gate leading into a transformer or substation compound.

Having verified that you are at the correct location the following observations can tell you a lot about what you may encounter:

• Broken locks, doors or gates may indicate that unauthorized entry has taken place
• Storage of non - electrical materials adjacent to or within the substation and switch room buildings or transformer compounds may indicate that the security of these area has been compromised, i.e., unauthorized persons have keys
• The storage of flammable materials next to electrical apparatus may also create a fire risk
• The storage of any materials may also impede safe access and egress to and from these areas
• Building defects such as roof leaks, broken guttering and downpipes and blocked drains may indicate that water ingress into the substation or switch room has occurred
• Smoke damage around vents may indicate that a fire has occurred
• Smoke emanating from vents and doors warm to the touch may indicate that there is a fire 

In external areas

• Accumulations of water may indicate that there are problems with the drains or bund dewatering systems
• Major oil leaks may indicate that switchgear or transformers have leaked

Do not enter any area where you suspect there is a fire, accumulations of water, major oil leaks, or the storage of materials which may cause a fire or may impede your safe access or egress. Always report your findings to your management and await further instructions.

Entry Procedure

Before you open the door of the substation or switchroom ensure that any Fire Protection Gas Suppression systems have been properly isolated by a competent person and secured.

When you first open the door and before proceeding into the substation or switch room use your senses to check for:

• Gas
• Pungent rotten egg smells which would indicate the presence of decomposed SF6 gas
• Crackling sounds and smells of Ozone which would indicate the presence of electrical arcs
• Evidence of oil leaks or ingress of water

If you detect any of these conditions do not enter, secure the door, report your findings to your management and await further instructions.

Although you may have established at the entry point that it is safe to continue to enter the substation or switch room you must still proceed with caution as there may be unsafe conditions within the substation or switch room which are not detectable from the doorway. You must continually use your senses to check for the presence of any unusual sounds, smells, or conditions as before.

Before you proceed into the substation or switch room check that there is an in-date operational fire extinguisher and that the emergency and normal lighting systems are operating properly. Check the Logbook to ensure that there are no existing conditions or warnings which would prevent the planned work taking place. If applicable also ensure that any in-switchboard fire protection gas suppression systems have been properly isolated by a competent person and secured.

As you proceed further into the substation or switch room, if you become aware of any unusual smells, sounds or conditions such as gas, major oil leaks, flooding of basement areas or the presence of any dusts or powders due the decomposition of SF6 gas immediately leave the area, secure the door, report your findings to your management and await further instructions.

• Once that you have established that there are no unsafe conditions it is recommended that the following engineering checks are carried out before any work is carried out:
• Check all circuit breakers are in their normal operating positions
• Test all battery tripping units are healthy
• Check all protection relays are indicating normal healthy conditions
• Check for any signs of compound leaks from cable termination chambers
• If applicable check all power factor correction units are indicating normal healthy conditions
• Check all heating and ventilation systems are operating normally
• Check for roof leaks or ingress of water
• If applicable check the basement de-watering pumps are operating normally
• Check that all safety equipment and tools are available and free from defect
• If applicable check that the First Aid box is correctly stocked

If any of these conditions are detected investigate further and report them to your management and await further instructions. And finally make an entry in the Logbook summarising the checks you have carried out and the purpose of your visit.

We hope this article on Guidance for Entry into Substations and Switchrooms was helpful. For more information from Horizon Engineering Solutions, please visit their CPD Member Directory page. Alternatively please visit the CPD Industry Hubs for more CPD articles, courses and events relevant to your Continuing Professional Development requirements.