Electricity can be hazardous to human health and safety in three primary ways: shock, arc flash and arc blast. There are also thermal hazards that can be quite serious. OSHA and NFPA 70E define a simple hazard threshold of 50 VAC. At Berkeley Lab (and across the DOE Laboratory Complex), we are often exposed to a variety of complex electrical hazards. For this reason, Berkeley Lab has adopted the following hazard thresholds. For a complete description and breakdown of the DOE Electrical Hazard Classification System, see Sections 2 & 3 of the LBNL Electrical Safety Manual (ESM).

If a circuit is powered from a source that is rated above the threshold, then it is considered hazardous. Shock and arc flash hazards trigger QEW requirements, while thermal hazards alone do not.

Shock Hazard Thresholds

Source	Includes	Thresholds
AC	50-60 Hz nominal	≥ 50 V and ≥ 5 mA
DC	All	≥ 100 V and ≥ 40 mA
Capacitors	All	≥ 100 V and ≥ 10 J
Batteries	Lead-Acid and Lithium Ion	≥ 100 V
Sub-RF	1 Hz to 3 kHz (excluding 50-60 Hz nominal)	≥ 50 V and ≥ 5 mA
RF	3 kHz to 100 MHz	A function of frequency

From Table 2.2.13 in the ESM

Arc Flash/Blast Hazard Thresholds

Source	Includes	Thresholds
AC power	50-60 Hz nominal	<250 V and the transformer supplying the circuit is rated >125 kVA <250 V and the circuit is supplied by more than one transformer ≥ 250 V
Sub-RF	1 Hz to 3 kHz (excluding 50-60 Hz nominal)	≥ 250 V and ≥ 500 A
DC	All	≥ 100 V and ≥ 500 A
Capacitors	All	≥ 100 V and ≥ 10 kJ
Batteries	All	≥ 100 V and ≥ 500 A
RF	NA	NA

From Table 2.3.3 in the ESM

Thermal Hazard Thresholds

Source	Includes	Thresholds
Sub-RF	1 Hz to 3 kHz (excluding 50-60 Hz nominal)	<50 V and >1000 W
DC	All	>100 V and >1000 W
Capacitors	All	<100 V and >100 J
Batteries	All	<100 V and >1000 W
RF	NA	NA

From Table 2.3.5 in the ESM