Hazardous Voltages

Scope

This experimental work instruction applies to experiments with hazardous voltages (>50 volts AC, or >120 volts DC) and involving:

• Non-propriety or modified electrical equipment; and / or,
• Experimental setups with open conductors or contacts (not meeting IP2X rating).

 

Pre-visit

User Principal Investigator shall provide the following to the Diamond Local Contact at least eight weeks prior to the experiment at Diamond:

• Essential Information Requirements (see below).

Assurances that User-provided equipment achieves the relevant:

• Essential Safety Requirements (see below).

Assurances that Users coming to Diamond achieve the relevant:

• Essential Competency Requirements (see below).

Assurances that the equipment is compliant with the safety requirements of the home institution.

Diamond Local Contact shall ensure compliance with the following for Diamond provided equipment:

• Essential Information Requirements (see below);
• Essential Safety Requirements (see below);
• Essential Competency Requirements (see below).

 

Pre-experiment

Diamond Local Contact shall ensure that the above pre-visit requirements for User provided equipment is reviewed by a competent electrical technician or engineer.  This shall include inspection of the equipment.

 

Experimental Setup

Diamond Local Contact & User Visit Principal Investigator shall collaborate to ensure adherence to:

• Essential Experimental Setup Checklist (see below).

 

Operation

Diamond Local Contact & User Visit Principal Investigator shall collaborate to ensure adherence to:

• Essential Operational Checklist.

 

Essential Safety Requirements

Experimental setup and equipment shall be:

• Rated and compatible for the intended voltage, current, sample environment and setup conditions at Diamond
• Suitably tested by a competent person or body to ensure safe operation at Diamond.  Non-standard set-ups shall be commissioned and tested prior to coming to Diamond;
• Safely packaged & transported to Diamond to prevent damage that could affect safe operation;
• Suitably risk assessed, identifying failure modes, safety controls and emergency controls (ref. Essential Hazard & Failure Mode Checklist);
• Electrical conductors are not exposed and cannot be contacted by persons when the equipment is energized (must be shielded to achieve IP2X rating).  Where IP2X cannot be achieved, access to hazardous voltages must be controlled (e.g., via interlocks);
• Fitted with suitable safety devices (e.g., grounding, emergency stops, RCD / RCCB / RCBOs, MCB / MCCBs, fuses, etc.);
• Labelling: Equipment CE / UKCA marked or has an appropriate declaration of conformity; and
• In compliance with the Electricity at Work Regulations, including the requirements relating to work on or near live conductors and competency.

 

Essential Information Requirements

Information required:

• A full description of the proposed experimental setup & technical specifications.
• Energy details including voltages, current, possible unsafe or fault conditions, etc.
• Sample environment details including what the equipment will be used for, energies used, etc.
• Risk assessment and safe operating procedure / instructions for any equipment not provided by Diamond.
• Unique Identification mark of any equipment not provided by Diamond, i.e., its serial number.
• Assurances and evidence that equipment has full up-to-date test and calibration certificates (where applicable).

 

Essential Competency Requirements

Person setting up experimental equipment shall:

• Have sufficient experience of setup, test and operation of the equipment, hazardous voltages, risks and required safety controls to ensure safe setup;
• Have sufficient skills and be practiced in the setup and operation of the equipment, hazardous voltages, risks and required safety controls used in the experiment; and
• Have sufficient knowledge of the essential safety requirements of the equipment to ensure safe setup.

Persons operating equipment shall:

• Have sufficient experience and be practiced in safe use of the specific equipment, power and required safety controls to ensure safe operation;
• Have sufficient skills and be practiced in safe use of the specific equipment, power and required safety controls used in the experiment;
• Have sufficient knowledge of the essential equipment safety requirements, power, and safety controls to ensure safe operation.  This includes knowing when to stop operations and what to do in the case of an emergency; and
• Be suitably supervised if they do not have sufficient skills, knowledge, and experience.

 

Essential Experimental Setup Checklist

• Persons setting up the equipment meet the Essential Competency Requirements.
• Electrical conductors are not exposed and cannot be contacted by persons when the equipment is energized (IP2X achieved).
• Guarding: Sufficient guarding is in place to achieve IP2X, where open conductors are needed (e.g., for sample contact).
• Component ratings are suitable for the working voltages / currents.
• Protective devices are in place and appropriate for the duties of the equipment – consider voltages and current when examining RCD, MCBs, fuses, etc.
• Power status: It is clear and unambiguous when the equipment is live or powered off.
• Stored energy: Where there is a stored energy risk, components are discharged or shorted as part of the make-safe process.
• Energy setting of the equipment (voltage, current, power, etc.) has been set to the lowest level possible for the work.
• Grounding: Where appropriate, equipment and test set-ups are grounded with sufficient capacity cable / braid.
• Electrical safety devices are in place (e.g., emergency stop) and tested & confirmed as functional.
• Remote shutdown is enabled for all electrical experimental equipment.
• Visual inspection of the setup.
• Manufacturer’s instructions (where applicable) have been followed during setting up.
• Modifications (where applicable) from planned setup have been checked by a competent person.
• Signage and labelling are sufficient to warn of hazards and risks.

 

Essential Operation Checklist

• Persons operating the equipment meet the Essential Competency Requirements.
• Visual check of the setup is carried out before every operation.
• Modifications to the planned setup are done by a competent person and checked against the Essential Experimental Setup Checklist.
• Safety controls stated in the User Experimental Risk Assessment (ERA) (or lab form) are applied, and the ERA has been graded and validated.
• Safety controls stated in both the beamline risk assessment and any Diamond equipment risk assessment are applied.
• Lone-working prohibition is in place and understood by all persons supervising the experiment.
• Suitable supervision of the experiment is in place to ensure safety.
• Failure modes of the set-up are understood by all persons supervising the experiment.
• PPE identified on the risk assessment is provided, it fits, it is in good condition, and all operators are proficient in its correct usage.
• Emergency conditions and required action is understood by all persons supervising the experiment.
• Emergency actions on equipment failure, un-commanded energy discharge or “trip” (of e.g., supplies) is understood by all persons supervising the experiment.
• Emergency action on the fire alarm sounding is understood by all persons supervising the experiment.
• Emergency action / first aid action on electrocution is understood by all persons supervising the experiment.
• Emergency action on gas detection sounding is understood by all persons supervising the experiment.
• Emergency action on power outage is understood by all persons supervising the experiment.
• If safety issues are identified, the Principal Beamline Scientist (PBS) must be contacted, and the issues resolved before continuing with the experiment.

 

Essential Hazard & Failure Mode Checklist

The main hazards are:

• Electrical energy burns from contact with energized circuit / stored energy;
• Electrocution from contact with energized circuit / stored energy;
• Arc-flash from high voltage failure;
• Hot surface contact;
• Fire resulting from ignition of flammable materials due to spark / overheating;
• Fire resulting from ignition of equipment / cabling / samples;
• Explosion resulting from catastrophic failure of equipment / component (e.g., HV capacitor failure); and
• Physical injury resulting from constant current supply shorting (e.g., across rings on fingers).

Principal failure modes are:

• Poor equipment and / or system design;
• Poor installation / setup;
• Poor maintenance of equipment;
• Inadequate repairs or modifications;
• An unsafe system of work; and
• Operator error, poor training / supervision.