Is a 250V fuse appropriate for a 115V AC IEC320 connector?

Sun May 13 10:53:22 EDT 2018

Hey, I'm playing with a simple ADC circuit being polled by a Raspberry PI, but almost any other microprocessor with SPI could do the job. A faster ADC with I2C is on my project list right after this one, so I am getting interested in the field. 

What would the safety considerations / requirements for an ADC logger application monitoring AC mains voltages:  

(from here <https://www.quora.com/Is-the-power-system-in-the-US-technically-110-115-or-120VAC-How-about-220-or-is-it-240-or-235VAC> )

Today utilities are required to supply you with voltage that doesn’t vary from 120 volts by more than 5% either way. So that would mean your voltage should be between 114 and 126 volts.

Would this be a case of a bi-polar single-ended input SAR ADC application? Any recommendations for a chip that does this (AC mains applications) already? 

-----Original Message-----
From: Rob Seastrom [mailto:rs at seastrom.com] 
Sent: Friday, May 11, 2018 10:23 PM
To: Zachary Yarashus <zyarashus at gmail.com>
Cc: Robert Seastrom <rs at seastrom.com>; samudra.haque at gmail.com; tacos AMRAD <tacos at amrad.org>
Subject: Re: Is a 250V fuse appropriate for a 115V AC IEC320 connector?

Zach is right.  One footnote is that the AC and DC interruption ratings for fuses are not the same (make some sense when you consider that the AC has 120 zero crossings a second.  My recollection is that your typical glass north american automotive fuse (type SFE or AGC) is rated at 32 volts DC and 250 volts AC.  Learned this when designing equipment to run off -48vDC in a CO environment.

-r

> On Apr 27, 2018, at 6:29 AM, Zachary Yarashus < <mailto:zyarashus at gmail.com> zyarashus at gmail.com> wrote:

> 

> A fuse with a higher voltage than the line voltage is fine. Given that, the amperage is the critical part, and maybe fast/slow blow depending on your application.

> 

> If you intend to use it with a switching supply that accepts 120-240VAC (which are becoming more common) it should have a 250V fuse in the case that it is ever run from the higher voltage. If it can only be run from 120VAC, than any fuse with a voltage rating of greater than or equal to 125VAC should be fine.

> 

> Personally, I'd just use a 250V fuse since they seem to be more widely available than lower voltage fuses from what I've seen.

> 

> On Fri, Apr 27, 2018, 09:11 < <mailto:samudra.haque at gmail.com> samudra.haque at gmail.com> wrote:

> Requesting project design tips.

> 

>  

> 

> I’m designing a box that will be AC powered. I like an on/off switch, fuses, lights to indicate the box has power.

> 

>  

> 

> I wanted to use something like shown here.

> 

>  

> 

> The requirement for 250V fuse is embossed in the plastic. In north America, 115V is the pole-neutral house voltage for residential circuits. Is 250V here correct, or should we fit with another fuse voltage? Essentially the first device after this receptacle is a switched mode power supply.

> 

>  

> 

> 73, N3RDX

> 

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