argument with electrician

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mmm_max said:
I am saying that i need only # 4 for the two hot feeds to the breakers because the breakers should be balanced in amperage for each hot. 50 amps each side but the return will have to take the full 100 amps from both hots.
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What makes you think that each leg of a 100 amp service is only 50 amps?
 
MattG0311 said:
Retorque every season??????
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In the new electrical fundamentals dvd that came out this month Mr. Holt said you never are supposed to retorque. (that wasn't mentioned in the previous fundamentals dvd, I've watched that one at least 3 times) He said the wire will naturally relax after it's torqued and that is taken into account in the initial torquing requirement. Retourqing after the wire relaxes will cause the wire to deform, and over time, continuous torquing will continue to make the wire thinner. So it should be one proper torque and you are done. Also, if you ever need to take a wire off a terminal, you need to cut the part that was under the lug off so you have a fresh end for torquing.
 
Sea Nile said:
In the new electrical fundamentals dvd that came out this month Mr. Holt said you never are supposed to retorque. (that wasn't mentioned in the previous fundamentals dvd, I've watched that one at least 3 times) He said the wire will naturally relax after it's torqued and that is taken into account in the initial torquing requirement. Retourqing after the wire relaxes will cause the wire to deform, and over time, continuous torquing will continue to make the wire thinner. So it should be one proper torque and you are done. Also, if you ever need to take a wire off a terminal, you need to cut the part that was under the lug off so you have a fresh end for torquing.
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I was being facetious. But that is interesting about the wire essentially becoming thinner retorquing “every season.” While I’ve never retorqued a connection I am definitely guilty of relanding cables without stripping them back out…habits to break!
 
Phil Timmons said:
This. This whole thing.

This is why I require all customers to have successfully completed therapy.

And provide references from prior electricians.

And to pay for all services in Vodka.
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I'll tell ya what...I got a good laugh out of this one. A good chuckle each morning before real work should help my demeanor with others all day. LOL

50 + 50 = 100. I mean.....that is a true statement. :ROFLMAO:
 
mmm_max said:
Trying to resolve an argument with my electrician. He says I need awg 1 for service to a 100 amp subpanel. I am saying that i need only # 4 for the two hot feeds to the breakers because the breakers should be balanced in amperage for each hot. 50 amps each side but the return will have to take the full 100 amps from both hots. Am I wrong. Distance is around 80 feet from the feed.
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Are you and your electrician talking about the same type of conductors? It seems like he's thinking aluminum and you're thinking copper. If he's using aluminum he is correct in using #1. 310.12 says he could use #2 aluminum if it fed a panel that serves all loads in a single family dwelling but not for a sub panel. It seems that you're thinking of copper and, according to 310.12, the #4 would be correct if it was used for feeding a 100 amp panel that serves all loads in a single family dwelling. Again, not for a sub panel. For a sub panel you have to use #3 copper or #1 aluminum, so I'd say if he's using #1 aluminum, he's correct.
 
growler said:
What makes you think that each leg of a 100 amp service is only 50 amps?
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This is a valid question that apprentices will have. I also had a similar question in the past regarding total ampacity of y transformers 208/120? My question was wether nameplate current was determined based on current out put on one leg phase or total of all three legs or phase to phase. I think last info I received was answered as being current phase to phase 2 phases? thus I’m still not sure
 
Jpflex said:
This is a valid question that apprentices will have. I also had a similar question in the past regarding total ampacity of y transformers 208/120? My question was wether nameplate current was determined based on current out put on one leg phase or total of all three legs or phase to phase. I think last info I received was answered as being current phase to phase 2 phases? thus I’m still not sure
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Do not ever think about a 'total ampacity'.

Current is always per line or 'leg'

The issue is converting kVA into amps. The only tricks are to be sure of what voltage you are using and how many phases there are. I cannot think of the last time I did not use the line-line voltage when determining the current in a circuit.
 
jim dungar said:
Do not ever think about a 'total ampacity'.

Current is always per line or 'leg'

The issue is converting kVA into amps. The only tricks are to be sure of what voltage you are using and how many phases there are. I cannot think of the last time I did not use the line-line voltage when determining the current in a circuit.
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So current is 1 line Phase leg to neutral but not Phase to phase nor total of all three legs? Also what about factoring in power factor to get warts?

I keep forgetting if watts is line or phase current times line or phase voltage Times Square root of 3 times power factor

Dela and y have these Variables reversed Will have to go back to my book
 
Jpflex said:
So current is 1 line Phase leg to neutral but not Phase to phase nor total of all three legs?
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Current is determined at a point (any point) on a single wire. So phase A, phase B, phase C, and/or neutral. Each could have a different current.

Voltage (difference) is determined by 2 points. So it could be phase A to phase B; or phase B to neutral ; or phase C to phase A; or any other pair.

Cheers, Wayne
 
mmm_max said:
Dennis, Are there electrician and then there are folks that say they are electricians? I like to check the numbers. I do my own wiring but only on three phase motors and the only panels that I have burned up have been because I failed to re-torque the damn aluminum wire lugs! Now I have a temperture meter and retorque every season. I learn some.
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In our buildings, mostly distribution panels we did semi annual FLIR cam surveys for hot spots, and if we were having nuisance tripping in MCP’s also would do some picture taking. Occasionally we would retorque, but mostly it might have been reterminate, and torque to spec. Sometimes by the time you found a bad termination, the wire was melted or burnt, so no retorque was involved, just fresh connections. If you keep retorqueing I agree you are gonna destroy that conductor.


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Re-torqueing even a day later and even no loads applied you can get up to a quarter turn especially on multiwire conductors. That will eventually leed to conductor failure.
 
Jpflex said:
So current is 1 line Phase leg to neutral but not Phase to phase nor total of all three legs? Also what about factoring in power factor to get warts?

I keep forgetting if watts is line or phase current times line or phase voltage Times Square root of 3 times power factor

Dela and y have these Variables reversed Will have to go back to my book
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Current is measured on a single conductor. Voltage is measured between two points.

Watts, or more appropriately kVA, has only two formula that you need to worry about.
Single phase: Volts x Amps
Three phase: Volts x Amps x 1.732

For simplicity:
Unless you are doing some actual engineering, you do not need to worry about the difference between delta and wye.
To determine how many phases I have, I count the number of different line-line voltages, while ignoring any neutral or center point ones. Of course if the are only two conductors, there is only a single voltage.
 
jim dungar said:
Current is measured on a single conductor. Voltage is measured between two points.

Watts, or more appropriately kVA, has only two formula that you need to worry about.
Single phase: Volts x Amps
Three phase: Volts x Amps x 1.732

For simplicity:
Unless you are doing some actual engineering, you do not need to worry about the difference between delta and wye.
To determine how many phases I have, I count the number of different line-line voltages, while ignoring any neutral or center point ones. Of course if the are only two conductors, there is only a single voltage.
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But what about power factor for reactive loads such as 0.80 or 0.90 to be factored in Volt x amp x Square root of 3 x(power factor) otherwise your current will computed much lower than actual. You would be calculating the circuit at unity power factor or 100%
 
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