Hi, I’m just a flatfooted MIT EE ('57), but I’ve been around the block enough times to recognize shoddy work when I see it. Here"s what I recently found inside of a fused disconnect switch on an outside wall of our home adjacent to the heat pump AC compressor-coil unit it services.
When that heat pump was replaced last month with a new one, the low voltage control cable wasn’t long enough to reach its connection terminals in the new unit. The HVAC installer (not a licensed electrician.) routed the old control cable and a piece of new cable into the disconnect switch by punching out a knockout in its back, spliced the conductors with wirenuts, finished up and said. "All done sir!" Putting 230 volts and low voltage control wiring in the same box is against code here in sunny Winchester, Taxachusetts, as confirmed to me by our town’s electrical inspector before I shot my mouth off.
This genius also used wirenuts to connect the new 230 volt wires he ran to the unit to the cut off stubs of the old wires he left in the terminals of the switch. Maybe he couldn’t find his screwdriver to use the terminal screws? I made the HVAC company come back and do the job properly before I paid them.
By the way, that company is listed by the HVAC manufacturer as a "Trane Comfort Specialist". Trane proudly describes those specialists this way:
************ All dealers are not created equal. Which is why you must be thorough when selecting one. But, here’s something that will make your search a little easier. Just look for the Trane Comfort Specialist badge. It will indicate a Trane dealer of the highest standing a dealer that is committed to excellence in every aspect of his business, from installation and service, to customer care and employee training. The Trane Comfort Specialist designation is not easy to come by. Dealers qualify for this honor on a yearly basis by meeting Trane's stringent standards for professionalism and technological expertise. When it’s time to purchase a heating and air conditioning system put your comfort in the hands of an Independent Trane Comfort Specialist dealer. ***********
After my experience with them, I'd hate to meet the guys who couldn’t make that cut.
Best Regards, Jeff -- Jeffry Wisnia (W1BSV + Brass Rat ('57 EE)
Just to play devils' advocate....exactly what is the problem? The last t-stat wire I looked at was rated at 300 v....more than enough. And, wouldn't the outer jacket of the t-stat wire be considered a "raceway," much like the outer jacket of Romex? Finally, most thermostats are glorified switches, and won't be confused by a little induced voltage, as would a PLC.
On a more sober note, the running of the t-stat wire is a matter of controversy. HVAC guys typically run it either with the line set, or 'free-form' to the unit, where it is provided with a little cord-sized plastic bushing entry. And, as this pic shows, it often is run in the flex with the power wires, for reasons of appearance, protection, and convenience. I have yet to find a HVAC tech who is either trained or equipped to run flex, pipe, or anything electrical. The local college HVAC curriculum teaches a lot about controls, but nothing about the NEC. As best as I can tell, installers spend most of their apprenticeship bending metal, and techs are focused on superheat.
Re: Found inside of a fused disconnect switch #105629 06/10/0506:31 PM06/10/0506:31 PM
Why is that white wire spliced to the red wire? Why even splice - a new install should have had wires long enough to terminate on the proper terminals neatly. To me it looks like poor workmanship, but then again "neat" is hard to inforce. Ken
Re: Found inside of a fused disconnect switch #105630 06/19/0509:41 PM06/19/0509:41 PM
The t-stat wire may be rated at 300v, but the system energized is rated at 24v, hence the 2 diff species. Inductance may not be an issue(digital, microprocessor controlled t-stats very popular nowadays), but accidental cross contact could burn up a few things. How about the bare grounding conductor in that disco, starts out at the rear, ends up at front lower left side-I'd feel better if that was more isolated from the live front of the disco...And yes, wtf's with that 1" splice??
Re: Found inside of a fused disconnect switch #105631 07/06/0504:46 AM07/06/0504:46 AM
Looks like the "genius" ran an oversize 230v cable to the box and couldnt fit it in the switch terminals. Wirenuts aren't common in NZ but they are available. I am guessing that the wirenuts used in this case were inadvisable because of the difference in wire sizes being spliced ??
Is it fair to say that only wires of the same size should be joined with wirenuts ?
Re: Found inside of a fused disconnect switch #105632 07/06/0509:23 PM07/06/0509:23 PM
Kiwi, Wire-nuts are packaged with a listing of all the wire combinations for which they have been evaluated. Typically, this will include several combinations of differenttly sized wires. No package handy? Visit the mfr. web site for the info.
Unlike practices in other parts of the world, here in the US wirenuts are essentially the only means used to connect wires smaller than #6; with larger wires, other types of hardware start to be used.
Re: Found inside of a fused disconnect switch #105633 07/14/0506:11 PM07/14/0506:11 PM
CaOP- I think you're seeing white wire- probably from romex or other cable assembly- being used as a current-carrying conductor. They SHOULD be re-colored to signify their use as "hots." Since this is a single phase install, motor rotation is not an issue here.
Re: Found inside of a fused disconnect switch #105635 07/16/0505:50 AM07/16/0505:50 AM