5-inch ESD Casters Measured at 10⁹ Ω: Why PRIMEAG Did Not Ship This Lot

Written by the PRIMEAG engineering team. Measured 10/2026.

An ESD trolley only works if its casters actually carry charge to the floor. Many casters are sold with an “anti-static” label but have never been measured. So for every lot of ESD casters (photo: 5-inch swivel casters for parts trolleys), PRIMEAG measures resistance with a dedicated meter before the casters go anywhere.

How we measured

Instrument: TR1800 Environment & Megohmmeter with two external 5 lb electrodes placed on the caster tread, test voltage 10 V (the quick-screening level). The meter also logs temperature and humidity, because the resistance of ESD materials changes with ambient humidity.

Results

Both readings are above the 1 × 10⁹ Ω limit that ANSI/ESD S20.20 and IEC 61340-5-1 set for ESD casters, trolleys and chairs (point-to-ground resistance through the caster). In plain terms: this lot of turquoise PU casters does not pass for trolleys used inside an EPA, even though the manufacturer’s catalogue calls it “anti-static”. That is exactly why this article exists — without the measurement, these casters would have been fitted to trolleys and delivered.

What PRIMEAG did

• This lot is not shipped for ESD trolleys. The turquoise casters are used on standard (non-ESD) trolleys only, with no ESD label.
• Retest at the right voltage. For materials at 10⁶ Ω and above, acceptance testing must be done at 100 V; 10 V is for screening only. Following ESD caster lots are measured at 100 V, including point-to-ground once fitted to the trolley.
• Only passing lots are shipped: point-to-ground resistance through the caster < 1 × 10⁹ Ω, with %RH, temperature and test voltage recorded on the delivery test sheet.

For the full test method for benches, floors and mats, see ESD resistance testing for incoming acceptance.

What to ask when you buy ESD casters

• Is there a measured value? Ask for an actual resistance reading, not just an “ESD” label in a catalogue.
• Under what conditions? Low humidity raises resistance; a result should state %RH, temperature and test voltage (10 V or 100 V).
• Is the caster bonded to the frame? An ESD caster only helps when frame, shelf and caster form a continuous path to an ESD floor.

PRIMEAG supplies 3–5 inch ESD casters (swivel, fixed, braked) loose or fitted to lean pipe and aluminium profile trolleys; only lots with point-to-ground resistance < 1 × 10⁹ Ω (measured at 100 V) are shipped as ESD casters, with the measured values.