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Author Topic: Wire Question  (Read 4670 times)

SPA-stick

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Wire Question
« on: June 08, 2004, 10:15:45 pm »
Basic Wire question

I'm having an old spa removed and a new one put in. I'm looking to determine what guage of wiring I have.  How can you tell if its 6 or 8 gauge wire?.  It doesnt say anything on the wire caseing.

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Wire Question
« on: June 08, 2004, 10:15:45 pm »

Brewman

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Re: Wire Question
« Reply #1 on: June 09, 2004, 07:14:58 am »
The wire should be marked somewhere along it's insulation.  
If it really isn't then you have a few options.
Can you remove a few inches of your hot lead wire, scrape the insulation off maybe 1/2" on one end, and take it to either a shop which sells this type of wire?
Compare it to the 6 and 8 gauge on the shelf and see what size yours is.  Or if you have a place nearby that has knowledgable employees take them a sample and ask for their opinion.  This would be an electrical supply store that caters to professionals.  I wouldn't trust a big box employee for advice in this instance.
Or measure the diamater of the wire only, not including the insulation, and see if there is a chart somewhere that gives the diameter of wire by the various gauges.
Not sure if this exists or not.
What size breaker is on that wire.  If you have a 50 amp or larger breaker, you need 6 gauge wire to comply with the NEC.  A 40 amp breaker would need 8 gauge wire minimum.  That wouldn't guarantee the size of your wire, but it might be a rough indicator.
Brewman
« Last Edit: June 09, 2004, 07:16:38 am by Brewman »
Brewman

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Re: Wire Question
« Reply #2 on: June 09, 2004, 10:02:57 am »
I am a scientist, I convert beer, wine and whiskey into urine.

Brewman

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Re: Wire Question
« Reply #3 on: June 09, 2004, 10:14:14 am »
Thanks!
Brewman

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Re: Wire Question
« Reply #4 on: June 09, 2004, 04:13:59 pm »
Hi Guys,

The table at the web site is not very useful to most folks in the U.S.  It is given in funny units, wherein a comma that appears to be for the thousands column is really a decimal divider to us.  Also, it is given in millimeters and the square millimeter for area.  And, this table provides only one of many overall diameters of the cable, including insulation (which can and does vary in thickness).

Try Table 8, Conductor Properties, in the National Electrical Code (NEC).  The actual sizes (diameter) in regular units of the 7-stranded conductors are:

AWG 8     0.049 inch (1.23 mm)
AWG 6     0.061 inch (1.56 mm)    

Brewman, the sizes and breaker ratings that you mentioned would be correct, if you used 60 degrees C (140F) wire.  But, you shouldn't.  THHN wire or equivalent 75 degree wire is usually required, in order to meet the UL standard and to be in compliance with the NEC.  There are 3 regular wire ratings - 60, 75 and 90 C.  The one that should be used for spas is 75C (167F).  Here are the ampacities as listed in Table 310.16, Allowable Ampacities of Insulated Conductors ... for copper conductors:

                  60degree          75degree          90degree
AWG 8          40 amp              50 amp              55 amp
AWG 6          55 amp              65 amp              75 amp

Additionally, manufacturers may specify somewhat different sizes, as specifically approved by the testing agency (UL, ETL, etc.).  And, they may require that the connection to the spa be done in a different standard size, e.g. #6. Usually, the electrician may select an appropriate size conductor up to the spa, but may need to connect to and use a short piece of another size wire to connect to the spa.  There are many reasons for other size wire.  One example is when there is a need to use a larger size, because a long wire run in the typical size would cause more than a 3% voltage drop.  This is not acceptable and a larger size wire is required.

Electro

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Re: Wire Question
« Reply #4 on: June 09, 2004, 04:13:59 pm »

 

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