Solid Core Alum #8 Conductors

[Chip O'Brian]

Opinions on 40 amp breakers supplied with #8 gauge solid core aluminum conductor. 1984 Build date. 1 dryer & HVAC condenser unit.

[Kevin Barre]

A 40 amp breaker should have a # 6 if it's aluminum. However, most dryer circuits require a 30 amp breaker. It may be possible to switch out the breaker for the dryer rather than rewire the circuit.

The data plate on the A/C unit should be reviewed as for minimum circuit ampacity and max breaker size for that unit. You can't make a final determination without that info. Depending on the size of the unit, it's possible that either the breaker or wire size is incorrect. Or they both could be if it's a large enough unit.

[John Arnold]

Chip - I assume you're asking specifically about the solid aluminum wiring, not the size of the breakers or conductors?
I would certainly write up any solid aluminum conductors as potential fire hazards due to excessive expansion and contraction with temperature changes resulting in poor connections, arcing sparking, overheating, etc.

[Scott Patterson]

This isn't branch wiring we're talking about here. Both circuits are 240 volt appliance circuits. Properly sized aluminum is approved and widely used for that use. However, I didn't mention it before since I can't really tell from the photo, but I don't think that the wire shown is #8. I suspect it's #10. In that case, it's too small even for a 30 amp dryer circuit.

That is true for stranded wire, but as far as I have seen not for solid alum wire.

[Chip O'Brian]

Kevin nice catch, breaker is over sized for conductor. It is definitly #8 conductor. Just ran back to property to verify.
As to solid core I appears accepted for 240.

As to HVAC it is not uncommon for OCPD's not to be changed when unit is repalced and I report it. In this case 35 amp max unit MFD2003. So more than 3 issues.

[Kevin Barre]

Well, I accidentally deleted my earlier post trying to clarify it. I've never modified a post here. Anyway, I skimmed the post quickly and didn't think about the fact that it was solid wire in question. I was focused on the gauge in general relative to breaker size. That will teach me to talk on the phone and post at the same time. My bad.

[Chip O'Brian]

That is true for stranded wire, but as far as I have seen not for solid alum wire.

Scott not being branch would 40 amp breaker to # 8 gauge 240 be accepted?

[Kevin Barre]

I couldn't recall whether solid wire is allowed (even if available in the proper gauge) for 240 v circuits. I know I've never seen it in use. I just called an electrician friend with about 30 years of experience and he couldn't say whether it was OK either. His 2003 code book didn't address it anyplace he could find. I'm sure someone else will chime in.

[Joe Klampfer]

The first photo on left appears to be a stranded # 8 alum conductor not solid, the photo on the right appears as a #10 solid aluminum. Typically aluminum conductors are req'd to be one size larger to carry the same amperage as their copper equivilants. So to carry a 40 amp load you would need either a #8 copper or a #6 aluminum. Whether it 120 v or 120/240 doesn't matter, it's the load amps which is of concern when discussing guage.

[charles buell]

Here is a picture of some brand new #8 solid conductor aluminum that I scavenged off some new construction. It is certaintly being used and allowed----still don't like the stuff much but I think as copper prices get higher we are going to see more of it----maybe even back to branch circuits #12.

[John Arnold]

To quote Jerry Peck from February 15, 2006, in response to a question about use of solid aluminum on 240 circuits:

"SINGLE strand aluminum is not good.

If the conductor is large enough to be stranded, then aluminum is not too bad (one reason is because then it is in a different type of terminal).

The aluminum wire itself has no knowledge of what the voltage on its circuit is, nor does it care."

[Michael Thomas]

Also from Jerry Peck, from the last time we ran this movie:

From the NEC. (bold is mine)
- 310.14 Aluminum Conductor Material.
- - Solid aluminum conductors 8, 10, and 12 AWG shall be made of an AA-8000 series electrical grade aluminum alloy conductor material. Stranded aluminum conductors 8 AWG through 1000 kcmil marked as Type RHH, RHW, XHHW, THW, THHW, THWN, THHN, service-entrance Type SE Style U and SE Style R shall be made of an AA-8000 series electrical grade aluminum alloy conductor material.

#8 AWG can be either solid or stranded, smaller than #8 AWG is to be solid, and larger than #8 AWG is to be stranded.

http://www.inspectionnews.net/home_inspection/electrical-systems-home-inspection-commercial-inspection/826-cu-al-breakers.html

[Jerry Peck]

Older #8 aluminum (which will typically be TW insulation) is rated for 30 amps.

Newer #8 aluminum (which will typically be THW, THHN, THWN, etc.) is rated for 40 amps.

In a 1984 house I would consider that as "older" and most likely being TW for a 30 amp rating.

Now, if the dryer only needs a 30 amp, then, as previously stated, change the breaker.

The one for the a/c is based on minimum circuit ampacity, which would be 30 amps, and if - *IF* - the name plate stated 30 amp minimum circuit ampacity and maximum HACR breaker size 40 amps, that would still be okay. However, if the a/c is that old (which means it needs to be replaced) the nameplate may say maximum "FUSE" size, meaning it requires a "FUSE" and not a breaker, or a "FUSE" at the unit disconnect and the breaker at the panel - but it would need a fuse for its required protection, not a breaker. Newer units typical state 'fuse of HACR breaker', giving the option for either / or.

[Jerry Peck]

To quote Jerry Peck from February 15, 2006,

...

The aluminum wire itself has no knowledge of what the voltage on its circuit is, nor does it care."

John,

I should have added "120 volt or 240 volt, both are the same voltage to ground ... 120 volts ... so it does not matter.