What is the spare thermowell specification?
BCA’s test probe used for site verification is 228mm long and 3.2mm in diameter. For proper insertion, the thermowell should have an open tip slightly larger than 3.2mm diameter, and the length of the assembly including isolation valve (if any) andthe test plug should not exceed 200mm length. This would ensure that the test probe is in direct contact with the water.
BCA also accepts spare test plugs without thermowell as long as the test probe is able to come in direct contact with the water especially for pipes with larger diameter.