50 amp spa panel

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TSET

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Ignoring the question of voltage drop, is it allowable to use copper 8-3 NM cable for 50 amp spa panel feeders, or is the heater question a factor, increasing the cable size to 6-3 (125%)?
The manufacturer has specified 8-3 in the drawing, if under 100 ft.
 
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8/3 NM should be ok for the spa panel if used under 100ft and running inside home (main to spa panel). the 125% is not require because the spa is not consider continues load. The heater in the spa does cycle. The conductors you should be consider about the heat factor are those from the spa panel to the spa.
 
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TSET said:
... is it allowable to use copper 8-3 NM cable for 50 amp...
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Ignoring everything but the above, the answer is NO.

334.80 ~ 310.16.

60? column as marc stated.

A #8NM has an ampacity of 40A.
 
The Panel is beint supplied by Manufacturer, Olympic Hot Tubs. It has a 50A gfi and 20 amp gfi breaker, as I recall form the pdf on the website.
 
QES said:
that was unprofessional of celtic to tell other be ignored. We are all professional in here.
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HUH?

PM me if you would please.

EDIT:
I think you have misunderstood my "ignore comment".

I did not mean to "ignore" the other posters (on the contrary, I even cited marc's post), but rather ignore all the other items in the OP.

TSET said:
Ignoring the question of voltage drop, is it allowable to use copper 8-3 NM cable for 50 amp spa panel feeders, or is the heater question a factor, increasing the cable size to 6-3 (125%)?
The manufacturer has specified 8-3 in the drawing, if under 100 ft.
Click to expand...
TSET said:
... is it allowable to use copper 8-3 NM cable for 50 amp ...
celtic said:
Ignoring everything but the above, the answer is NO.
Click to expand...
Click to expand...
 
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celtic said:
Ignoring everything but the above, the answer is NO.

334.80 ~ 310.16.

60? column as marc stated.

A #8NM has an ampacity of 40A.
Click to expand...


Based on the rule of thumb, as I understand it, you size your conductors in the 60 c column under 100 amps, unless you know the the equipment terminals are rated for 75 c, and then the 75 c column becomes available to size your conductors. While it may not be safe for me to assume that the terminals are so rated, based on some small print in an install diagram, do I otherwise have my facts correct?
 
TSET said:
While it may not be safe for me to assume that the terminals are so rated, based on some small print in an install diagram, do I otherwise have my facts correct?
Click to expand...
No! NM cable is always sized from the 60 degree column, regardless of the terminal rating.

334.80 Ampacity. The ampacity of Types NM, NMC, and
NMS cable shall be determined in accordance with 310.15.
The ampacity shall be in accordance with the 60?C (140?F)
conductor temperature rating...​
 
NM is never based on anything other than the 60? column [334.80]..you can use the 90? column for derating, but the final value cannot be higher than the 60? column - REGARDLESS of the terminations degree value (75?/90?).
 
TSET said:
Based on the rule of thumb, as I understand it, you size your conductors in the 60 c column under 100 amps, unless you know the the equipment terminals are rated for 75 c, and then the 75 c column becomes available to size your conductors. While it may not be safe for me to assume that the terminals are so rated, based on some small print in an install diagram, do I otherwise have my facts correct?
Click to expand...

Celtic,
I self-correct myself based on your reference to 334.80. My apologies for not checking this before the above reply. NM is strictly limited to the 60 amp column, other than derating. Thankyou for answering my question.
 
TSET said:
Celtic,
... Thank you for answering my question.
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Don't thank me....marc beat me to the punch both times :)



On the install instructions....was it #8 NM or just #8?
 
QES said:
equipment terminals will be in effect from main all the way to spa? or just just spa panel to spa?
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110.14(C) Temperature Limitations.
The temperature rating associated with the ampacity of a conductor shall be selected and coordinated so as not to exceed the lowest temperature rating of any connected termination, conductor, or device. Conductors with temperature ratings higher than specified for terminations shall be permitted to be used for ampacity adjustment, correction, or both.
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The lowest rated is your weakest link...everything else is also dependant on it.
 
celtic said:
On the install instructions....was it #8 NM or just #8?
Click to expand...
From the Olympic Spa website:

230 VOLT SUBPANEL WIRING INSTRUCTIONS
NOTE: The subpanel must be placed within 100 feet of the main electrical service panel, and between 5 (1.5 m) and 50 feet (15 m) away from the
spa. All electrical connections must be made in accordance with the wiring information contained in this manual and on the back of the field wiring
access panel of the control box.
Refer to the wiring diagram below.
1. Connect the #8 AWG, WHITE [NEUTRAL] wire from the Neutral/Ground Bar on the main electrical service to the WHITE [NEUTRAL, Panel
Neutral, Pigtail] of the subpanel.
2. Connect the #8 AWG, BLACK [L1] wire from the main electrical service to the subpanel [terminal L1].
3. Connect the #8 AWG, RED [L2] wire from the main electrical service to the subpanel [terminal L2].
4. Connect the #10 AWG, GREEN wire from the Neutral/Ground Bar on the main electrical service to the GROUND terminal of the subpanel.
5. Connect the #8 AWG, WHITE [NEUTRAL] wire from the subpanel breaker to the Neutral terminal on the spa?s control box.
6. Connect the #8 AWG, BLACK [L1] wire from the subpanel breaker to terminal [L1] on the spa?s control box.
7. Connect the #8 AWG, RED [L2] wire from the subpanel breaker to terminal [L2] on the spa?s control box.
8. Connect the #8 AWG, GREEN wire from the GROUND terminal of the subpanel to the GROUND terminal in the spa?s control box.
9. Bond the spa to all exposed metal equipment or fixtures, handrails, and concrete pad pre N.E.C. and all local codes.​
Click to expand...
 
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