Primary Wire for 120/240 Volts AC?

[minuteman62-64]

I'm doing some repairs on my electric spa heater. This will involve replacing some pieces of #10 and #12 stranded wire. The only stranded wire in those sizes I can find in my local hardware store/HD store is Primary wire - which I understand is usually used for DC applications in boats, autos, etc.

Is Primary wire OK for use with 120/240 volt AC applications? If no, what type of wire and where do you get it? The wire that's in there now has no identifying marks that will tell me what type of wire it is.

 

[MTboatguy]

10-12 sounds a bit small, HD should have black jacketed wire for 120/220 hanging on their spools, I know I was able to purchase it when I ran the 220 feed for my garage. What happened to the wire that is on the system now? burns, breaks, old, etc?

 

[bonz_d]

All of the big box stores should have THHN stranded wire for this purpose. It needs to be sized by the amp draw.

 

[bigdee]

If this is for a wet location use wire marked "THWN" or as "THHN/THWN"....the W means suitable for wet locations. I am assuming that this is for internal control wiring. If it is the branch circuit and not in counduit you need romex cable.

 

[minuteman62-64]

Found it! I was looking in the wrong place - in my HD it's down by the bulk wire. In fact, for the few feet I need I can buy it off the spool for about $5.

Long story/history on the existing wiring. Bought the spa in the 1980's - on of the first generation with the electronic circuit boards. First problem, I called Spa Guy - he didn't know how to diagnose the circuit boards so offered to re-build the heater system with manual (air button) controls. He must have done it OK because it has pretty much worked for the past 30 or so years. However, he was far from a neat-freak. Inside the box looks like a wire nest, constructed by a rabid rat, above the components. So, when I need to replace something (as now, with a relay), I have to dig down through the rats nest of wires to get to it.

So, hoping to get another couple of years out of this spa, I plan on re-routing the wiring, so everything is more accessible, and making a few lengths longer, so the two halves of the control box will separate (open) without taking the entire unit out of the spa.

Overall the conversion to manual operation has worked well - the circuitry is easy to follow and diagnose and I've been able to do all of the repairs since.

 

[MTboatguy]

I have found by experience, the only way to buy certain types of wire at HD, is off the spool, they have a lot of stuff, that is not pre-packaged and it turns out cheaper.