All conductors can be affected by EM fields. Thermocouples containing iron, 
like Type J and K, are more susceptible than others.

I’ve experienced some susceptibility of Type T thermocouples in some instances.

I don’t have any experience with, “The J and K type thermonuclear probes.”☺

FWIW, even though there are some sources that state constantan is a 
copper/nickel alloy (Type T thermocouples use a copper/copper-constantan 
system), NIST once held the position that they would not calibrate 
thermocouples containing constantan, unless the allow used to draw the wire was 
assayed, due to impurities in and other uncertainties with the alloy’s content. 
IIRC, iron was a constituent commonly found in constantan.

Peter Tarver

From: Doug Powell []
Sent: Tuesday, September 20, 2016 08:58

The first thing you should check however, is if there is any interference.  The 
J and K type thermonuclear probes do have iron (Fe) content and are susceptible 
to magnetic or RF fields.  If you have such fields present they can result in a 
much wider range of readings than you might otherwise expect.

Also type T thermocouples have no iron content
The information contained in this message may be privileged and confidential. 
It is intended to be read only by the individual or entity to whom it is 
addressed or by their designee. If the reader of this message is not the 
intended recipient, you are on notice that any distribution of this message, in 
any form, is strictly prohibited. If you have received this message in error, 
please immediately notify the sender and delete or destroy any copy of this 

This message is from the IEEE Product Safety Engineering Society emc-pstc 
discussion list. To post a message to the list, send your e-mail to 

All emc-pstc postings are archived and searchable on the web at:

Attachments are not permitted but the IEEE PSES Online Communities site at can be used for graphics (in well-used 
formats), large files, etc.

Instructions: (including how to unsubscribe)
List rules:

For help, send mail to the list administrators:
Scott Douglas <>
Mike Cantwell <>

For policy questions, send mail to:
Jim Bacher:  <>
David Heald: <>

Reply via email to