Eddy Current
Senior Member
Can anybody tell me where they are getting the 1.59 multiplier for the practice problem on page 230?
If the ungrounded conductors for a 40A circuit are increased in size from 8AWG to 6AWG the circuit equipment grounding conductor must be increased from 10AWG to ____?
There's no need for a multiplier when proportionate upsizing is within gage size range. If you upsize 2 gage sizes, then you upsize 2 gage sizes... i.e. #8 to #6 ungrounded is two (2) AWG sizes, so you upsize #10 grounding to a #8.Where does the multiplier 1.59 come into play?
I would not accept that as a useful rule of thumb, without first creating a spreadsheet of possible upsizes, and proving it works in all cases. Have you already done just such an analysis? If so, I would appreciate getting a copy of the spreadsheet, so that I can put it in my binder of "technical tidbits" that I keep at the office.There's no need for a multiplier when proportionate upsizing is within gage size range.
Actually I do have a spreadsheet analysis. However, to accept the "rule" mentioned earlier you only have to adopt the AWG diameter formula as the basis for proportioning...I would not accept that as a useful rule of thumb, without first creating a spreadsheet of possible upsizes, and proving it works in all cases. Have you already done just such an analysis? If so, I would appreciate getting a copy of the spreadsheet, so that I can put it in my binder of "technical tidbits" that I keep at the office.
Link to spreadsheet:I would not accept that as a useful rule of thumb, without first creating a spreadsheet of possible upsizes, and proving it works in all cases. Have you already done just such an analysis? If so, I would appreciate getting a copy of the spreadsheet, so that I can put it in my binder of "technical tidbits" that I keep at the office.
It's supposedly the 'framework' for all this, just like E = IR, so it's an unchanging reference point. But, it's very difficult to go the other way, from real world diameter measurements and then correctly infer the rule behind it.Therefore, why should we use accepted math proportioning standards to do this evaluation???
Does it provide a tolerance?
but who is to say how close it must be?