interesting new requirement in 2017

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petersonra

petersonra

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670.6 Surge Protection. Industrial machinery with safety
interlock circuits shall have surge protection installed.
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I wonder what this means in practice.

Is surge protection at the service acceptable?

How about at the main disconnect/OCPD for the machine?

Or is it asking for surge protection on the safety circuits themselves, or at least the power to them.

And what do they mean by safety interlock circuits.

Note that it does not require a surge protection device, only surge protection. Most DC power supplies these days have some kind of surge protection built in. if the requirement is for the safety circuits themselves to have surge protection wouldn't the power supply already provide that?
 
How come these new ridiculous worded codes get past us.

There needs to be a better way. I tried to look at the new proposals once and got overwhelmed as to how many ,and unorganized it seemed.
 
I found this doing a quick Web search.

Article 670.6 addresses industrial equipment with safety interlock circuits. It states that “industrial machinery with safety interlock circuits shall have surge protection installed.”
The concern is that electrical surges may cause the interlocks to fail independent of the machine operation. This could pose a significant safety factor for operators, as the intended safety mechanisms may be disabled unbeknownst to the operator.
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https://blog.nema.org/2016/11/17/2017-nec-broadens-requirements-for-surge-protective-devices/
 
Article 670.6 addresses industrial equipment with safety interlock circuits. It states that “industrial machinery with safety interlock circuits shall have surge protection installed.”
The concern is that electrical surges may cause the interlocks to fail independent of the machine operation. This could pose a significant safety factor for operators, as the intended safety mechanisms may be disabled unbeknownst to the operator.
Click to expand...

I thought that the NEC doesn't get involved with design issues. Requiring surge protection here as a cure for this problem makes me wonder even more about the qualifications of people on the CMPs.

If there is a concern about interlocks failing it should be up to UL to come up with a fail safe standard.

-Hal
 
hbiss said:
I thought that the NEC doesn't get involved with design issues. Requiring surge protection here as a cure for this problem makes me wonder even more about the qualifications of people on the CMPs.

If there is a concern about interlocks failing it should be up to UL to come up with a fail safe standard.

-Hal
Click to expand...
just 1 of many "??" in NFPA-70.
 
hbiss said:
I thought that the NEC doesn't get involved with design issues. Requiring surge protection here as a cure for this problem makes me wonder even more about the qualifications of people on the CMPs.

If there is a concern about interlocks failing it should be up to UL to come up with a fail safe standard.

-Hal
Click to expand...



Manufactures have found that mandating device and various services results in more revenue than any other investment is cable of returning.
 
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