Questions tagged [nec]
6 questions
12
votes
4 answers
Why does the current carrying capability of a cable increase with temperature
I'm specifying cable for a VFD application and came across this table regarding NEC ampacities and corresponding cable size.
What I found interesting is that the ampacity increased with temperature for any environment (Free Air, Single Tray,…
SRR
- 917
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2
votes
1 answer
Why isn't this IR NEC signal being accepted by the receiving device?
I'm trying to transmit an IR NEC signal to a portable air conditioning unit. I have the remote control that came with the unit, and it appears to use the NEC IR protocol.
I've setup a receiving circuit so that I can observe the signal transmitted by…
John O'brien
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- 3
2
votes
4 answers
Difference between phase and polarity?
Long story short, I did a bit of a career change, I'm now doing electrical engineering with an architecture firm instead of embedded systems. So I've jumped from the simple world of DC to the land of AC electronics and it's definitely different…
audiFanatic
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1
vote
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NEC asic information from around 1990
I'm looking for datasheets with specification for the NEC ASIC/Gate Arrays from around 1990.
More preciselly, any information with specifications of their ASIC/Gate Array lines.
I would like to known the typical gate count and things like that from…
Hernandi F. Krammes F.
- 131
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0
votes
1 answer
Patch into IR receiver output signal
I have a LED string lights that can be controlled with an IR remote (e.g. ON/OFF, blinking mode, brightness, etc.) and the circuit looks like this:
FYI the lights work like this: The U1 IC controls the signal that is fed to the LED, with the BUTTON…
Razero
- 187
- 3
0
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0 answers
Transformer secondary conductor protection: how do NEC 240.21(C) and NEC 240.4(B) make sense together?
NEC 240.21 says all ungrounded circuit conductors require overcurrent protection, with a list of exceptions:
One of those exceptions is 240.21(C):
240.4(B) says that if you're under 800 amps, you can up-size your breaker to the next available…
Stephen Collings
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