Rectifiers

[quantum]

I do not see any section of the NEC that covers AC to DC Rectifiers. Am I overlooking it? I'm looking to size a breaker and fuses for the input circuit.

 

[zbang]

I don't think rectifiers are generally considered different from other utilization equipment. Unless it's specifically covered elsewhere*, I'd go with the nameplate input current and the usual branch circuit rules.

*It does depend on what the rectifier supplies and how it is built- motors, welders, theater equipment, telecom(?), and pipe organs all have separate code sections (I didn't look for others), but you can always call the manufacturer.

 

[quantum]

I was leaning towards contacting the manufacturer, but I wanted to be certain that I was not overlooking any NEC sections regarding them. Thanks for the info.

 

[310 BLAZE IT]

I agree with the above, you just need to take into account that it produces harmonics so I would count the neutral a current carrying conductor

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[Jraef]

Article 430.122 is generally considered to be referring to VFDs because article 430 in general is about motor controls, but it actually says "power conversion equipment". If you want to make an argument to NOT have to follow 430.122 for a general purpose rectifier, you could, because of it saying "as part of an adjustable speed drive", but it might just be easier not to fight it and size the input conductors accordingly. But even this doesn't address the OCPD requirements, just the minimum conductor size. The OCPD requirements are generally handled by the mfr during the listing process. If you are using something that is not listed, you are going to be using the "courtesy" untested SCCR of 5kA anyway, so what breaker or fuse rating in terms of kAIC is going to be somewhat irrelevant now. ANYTHING can handle 5kAIC, the real trouble is using something with that low of a rating, at least in any industrial environment.