Testing resistances.

[Matt0029]

If testing resistance and and you are say within 2-3 ohms of what the manufacturer specifics is that close enough? Is there a degree of error. Thanks

 

[ShaunCorbs]

Yes normally way off so anything 15 +below or above normally find above goes mental eg supposed to be 45 and it’s reading 300 etc

 

[Chuck]

For typical heating / plumbing fault-finding as long as resistances are within 10% of nominal they're almost certainly okay. If the values are critical the manufacturer's fault-finding guide will specify an acceptable range. Most components fail by going either (nearly) short- or open-circuit, very few fail by changing their value by a few percent.

 

[Ben-gee]

And don’t panic if your measuring a floor temperature probe and you looked up the values for 19 deg C and yours is way off -you’ve probably been warming it up in your hand too long, or left it next to your tea!

 

[Deleted member 120897]

Also don’t forget to disconnect it from the circuit.