HVAC Fused Disconnect has 30A rating but has 50A fuses

[seawulf]

I had my split system HVAC replaced 4 years ago at my residence in the San Diego area and it has been running fine. I recently had a problem with the unit tripping the main service 50A DP CB. In the process of checking out the system, I found that the fused disconnect – a MARS 83316 – is rated by the manufacturer for 30A. But, my unit had 50A fuses installed. MARS also distributes a model 83317 that is rated for 60A. The AC compressor panel states that the “Minimum Circuit Rating” is 35.9A with a maximum fuse/CB recommendation of 60A.

I was concerned that the 30A unit rating did not seem to support the manufacturer’s 35.9A minimum circuit requirement. And,I did not like the idea of using 50A fuses in a unit rated for 30A.

So, I took the panel, showing the manufacturer’s 30A rating, and the fuse holder with the 50A fuses to the installer’s office, asking for an explanation of the discrepancies. They told me the 30A rating was due only to the 30A fuses, not to any limitation on the box components. And, that they had replaced the original 83316 unit’s 30A fuse holder with a 60A fuse holder (yes, it does seem to physically fit just fine). By doing so, they said, the original 30A rating is upgraded so that it meets the 36.9A minimum circuit rating.

This seems strange to me. I would think the unit’s rating represents the manufacturer’s maximum recommend current rating, regardless of any other limitation imposed by the fuses, themselves.

So, I am trying to find out if I have a system that meets code requirements.

What are your thoughts?
Thanks,
Charlie

[Jerry Peck - Codeman]

Hi Charlie,

First, let's start here.

And, that they had replaced the original 83316 unit’s 30A fuse holder with a 60A fuse holder (yes, it does seem to physically fit just fine). By doing so, they said, the original 30A rating is upgraded so that it meets the 36.9A minimum circuit rating.

What they did is violate the UL listing, voiding the UL listing, which is in itself a NEC (National Electrical Code) violation.

From the 2005 NEC (from 4 years ago when it was modified and installed), the wording in the 2008 NEC, which would be used for the replacement disconnect is exactly the same, and has been for many code editions. (underlining and bold are mine)
- 110.3 Examination, Identification, Installation, and Use of Equipment.
- - (B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

When they removed the interior for the 30 amp disconnect and installed the interior of the 60 amp disconnect, they modified the disconnect, making it no longer as it was listed and labeled (you read the labeling on it which stated 30 amp maximum), making it not suitable for use.

The nameplate label of the a/c condenser unit needs to be followed, make that IS REQUIRED TO BE followed.

The nameplate on your unit states 35.9 amp minimum circuit rating, which means that ALL components of the circuit, which includes the disconnect, must be rated for 35.9 amps minimum. As you discovered, that disconnect was not.

The nameplate also specifies a maximum fuse or circuit breaker is 60 amp.

First, that is the maximum rating for the fuses, so unit may well work fine with 60 amp fuses in it. As compressors get older, they are harder to start, which caused more current to be drawn that was being drawn when brand new, also, there may be adverse weather conditions which are affecting it, however, if it starts and runs fine with 60 amps fuses installed, the system may work fine. However, being as the tripping only recently started happening, it may also be an indication that the unit needs servicing, possibly as simple as replacing the capacitor to as complex as the compressor is going bad (which does happen). I would get that check out, and, at this point, I would not put a lot of faith in the original HVAC contractor knowing and understanding what they are doing. If it is the compressor, most (if not all) compressor have a minimum warranty of 5 years, and your are still within that - so hire a new HVAC contractor to give everything a real good checking out, better to find a compressor going bad this year than next year when it is out of warranty. Still, though, it may only be a capacitor, which is cheap and easy.

Your next concern, though, is a good concern, as there are many things which go into testing, listing, and labeling for all electrical equipment.

While the very same enclosure *may* have been used by that manufacturer for both their 30 amp disconnects and their 60 amp disconnects, it is quite possible that there *is* a difference in size, metal thickness, wiring space inside, knock outs for conduits and wiring, among other things, not the least of which may be heat rise with the 60 amp fuse block installed.

Regardless of whether it *may* be the same enclosure for the 60 amp disconnect, the simple fact is that the HVAC contractor modified the UL listed disconnect and that disconnect now no longer has any UL rating, which means it is not allowed to be installed (unless, of course, there is additional labeling which states that it is also suitable for use with the 60 amp fuse block - I am presuming that is not present as you did not state it was present).

This seems strange to me. I would think the unit’s rating represents the manufacturer’s maximum recommend current rating, ...

It is. The maximum current rating is what is on the label.

So, I am trying to find out if I have a system that meets code requirements

Not at this time, no.

You have three basic issues:

- 1) Your unit is now tripping the 50 amp double pole circuit breaker.
- - I believe you may have an easy repair, possibly the capacitor, to a compressor which needs to be replaced, and is most likely still under warranty.

- 2) Was your unit, including that disconnect, installed in a code compliant manner?
- - No, it was not. As soon as the HVAC contractor modified that fused disconnect they voided the UL listing and labeling, and without a proper UL listing and without it being installed and used in accordance with that listing and labeling, the HVAC contractor created a NEC code violation of 110.3(B).

- 3) What else did they do which "was okay by them"?
- - The only way to know is to have another HVAC contractor come out and tell you what is wrong. You may be able to do some of this yourself by obtaining the installation instructions for the two units and checking the installation of each unit to see if each was installed according to its installation instructions, which are REQUIRED to be left with the equipment - did that HVAC contractor leave the installation instructions?

Another question for you: Was the replacement permitted and inspected? If not, it should have been.

[seawulf]

Jerry,
Thanks for the quick response! As for your questions:

- There is a 10 year warranty on my compressor and a 5 year warranty on "Manufacturer's Parts"

- There is nothing on the disconnect panel that addresses the use of ANY components different from those original to the 83316,

- Yes, I have the installation instructions. They describe, mostly plumbing, but do state to, "...be sure field wiring complies with local and national fire,safety, and electrical codes..." and there is a NOTE that requires a "...branch circuit disconnect of adequate size per NEC to handle unit starting current" and located, "...per Section 440.14 of NEC."

- No, the installation was not permitted and inspected. The installer indicated I could pull the permit, if desired. But, I assumed there would be no code/safety issues for a replacement system installed by a reputable, licensed HVAC contractor with an excellent record from the local BBB. Obviously, I was wrong.

In doing some troubleshooting of the tripping CB, I found, using a non-contact thermometer, that the terminals of the 50A main service CB were heating to over 190 deg F just as the CB tripped. I used the same device on the A/C circuit wire terminations in the disconnect, and everything there - temperature wise - was normal. Also, this circuit uses stranded AL cable from the main service CB to the disconnect. All terminations have, what I assume to be anti-oxidant paste covering the terminations. BTW, the disconnect panel does require the paste to be used for Al wire terminations. I do not know anything about the Amp/Temp rating of this cable. All of the printing on the exposed cable is faded. I did get a caliper on an exposed 1/8 " and non-activated segment at the CB and it measured 0.23 inches diam. The tables indicate this is AWG 3! I don't believe it. I measured a number of times, but had the same orientation on the cable. So, I might have been measuring a somewhat flattened cable.

I did find that one of the set screws on the 50A breaker was loose enough for me to take about 1/8 turn on it, without much effort. After that, I ran the compressor continuously for 2 hours (typical trip was after about an hour of cycling ops) and there was no trip, and the CB terminals never rose to over 125 deg F (OAT was in the mid 90's and other CB terminations were running about 100 deg F). I realize these screws have specific torque requirements, and I have a inch-lb torque wrench. But, I do not know what the torque requirements are, as I do not have the CB installation instructions.

But, a few days later, I started getting the same tripping behavior and the CB terminals were heating, again.

At this point, I am really wary of any HVAC contractor not personally known to me. And, the only one that is personally known to me is the current installation company. My nephew is a local painting contractor and has recommended a good licensed electrical contractor that he trusts. Perhaps, I should have he check out the generic electrical components of the system, replace the disconnect and pursue a HVAC contractor if I still have the tripping problem, afterwards.

Charlie.

[Jerry Peck - Codeman]

Hi Charlie,

- No, the installation was not permitted and inspected. The installer indicated I could pull the permit, if desired.

In Florida, I would recommend reporting that contractor to: 1) the city; 2) the county; and 3) the state.

In Florida, they would most likely be state licensed, although there are some contractors who opt for local county licenses (although I don't know why, with a state license they can work in any county in the state, with a county license they are limited to that county). By reporting them to each jurisdiction you increase their slap on the wrist and make more people aware of their business practices.

In Florida, as licensed contractors they are obligated to; 1) pull the permit; 2) do the work in accordance with the code even if you pulled the permit as a homeowner, and, as a homeowner pulling the a/c permit you would likely not have been able to, meaning they would have to pull the permit anyway.

I reference the above "in Florida" so that if your state has similar licensing laws you could follow the same path.

BTW, the disconnect panel does require the paste to be used for Al wire terminations.

Using anti-oxidant paste is not a requirement for any aluminum conductor or terminal, it is just good practice as it may (probably does) reduce and delay the oxidizing of the aluminum conductors.

I did get a caliper on an exposed 1/8 " and non-activated segment at the CB and it measured 0.23 inches diam. The tables indicate this is AWG 3! I don't believe it. I measured a number of times, but had the same orientation on the cable. So, I might have been measuring a somewhat flattened cable.

If the terminations in the disconnect and the condenser unit, and / or the conductor insulation, are only rated for 60 degrees C, then #3 AWG would be required for 60 amps - you would need to use the lowest of all the ratings, using a higher rated conductor does not help if the terminals are also not higher rated.

If the terminations are rated for 75 degrees C as is the conductor, then you could use a #4 AWG for 60 amps.

If only for 50 amps you could drop one wire size at each condition, i.e., #3 AWG could be #4 AWG and #4 AWG could be #6 AWG.

I did find that one of the set screws on the 50A breaker was loose enough for me to take about 1/8 turn on it, without much effort.

Here is the problem with electrical terminals in general and with aluminum wiring in particular: Each terminal has a specified torque that terminal is to be tightened to and every electrician SHOULD carry the appropriate torque driver (most do not), do not re-torque. With aluminum, much more so than with copper, the aluminum conductor 'flows' outward under the torque of the terminal screw, when you come back later the terminal screw is "loose" so you re-torque again, and the next time the same thing, and the next, until you have finally torqued the terminal screw all the way through the aluminum and you have a broken conductor either hanging there loose or barely pinched under the screw.

At this point, I would recommend you get your best trusted electrical contractor out to look at all the electrician aspects of the installation, then I would recommend you call the building department and tell them that you had a new a/c installed 4 years ago and that the installing HVAC contractor did not pull a permit and some of the work is wrong, that you would like to pull a permit (note that the penalty for not pulling a permit when you should have is typically the permit again, meaning the permit will cost twice what it would have). Give them the list of things your electricians finds wrong.

Have the AHJ come out and do their inspections, which should include everything they would normally check anyway (which is not all that needs to be checked to make sure it is installed to the installation instructions, but what they consider they need to look at for their 'feeling-good' about the installation) and then signing it off.

At least now the installation is "legal" and you can go after the HVAC contractor on better standing.

If you try to go after the HVAC contractor and you did not want to make the installation "legal" the judge may hold that against you - the judge should not, they should follow the law which says the HVAC contractor is required to do blah, blah, and blah (everything in the installation instructions and in the code).

Be aware, though, that going after the HVAC contractor will likely cost you more than just having another HVAC contractor come in and go over everything, fixing whatever they find as they go over it all.

I know that homeowners do not like "permits and inspections", however, "permits and inspections" are there for a reason, and you discovered one of those reasons.

Does pulling a permit and having inspections mean it will all be done properly? No, of course not ... but you have a better chance for it,plus it gives you added backing and support when things go wrong.

[seawulf]

Jerry,
Thanks, again for all of the good info.

The contractors in California are all state licensed. So, I think I will contact the state license board to find out the contractor's responsibility wrt pulling permits for an HVAC install. My city building permit office may give me some good info as well.

The disconnect panel requires "... only 60 deg C / 75 deg C conductors on all field installed line and load terminations." It is rated for both Cu and Al wire.

I like your suggested approach to getting this all fixed.

BTW, the plot thickens...I discovered that my main electrical service is a Federal Pacific Electric / Stab Lok unit!!! After checking a number of sites, including your response on this site to a Dec 2008 question, I see that I have more problems - and more expense - than we have been discussing. Given that my observable problem with the 50A AC CB was overheating just before tripping. it really calls out for some immediate action.

Charlie

[Jerry Peck - Codeman]

Hi Charlie,

BTW, the plot thickens...I discovered that my main electrical service is a Federal Pacific Electric / Stab Lok unit!!! After checking a number of sites, including your response on this site to a Dec 2008 question, I see that I have more problems - and more expense - than we have been discussing. Given that my observable problem with the 50A AC CB was overheating just before tripping. it really calls out for some immediate action.

Correct, especially being that one of the two main problems with FPE is that their breakers have been known to NOT TRIP under even very heavy overload conditions. Basically like not having any overcurrent protection at all in those cases, except that you THINK you have protection - which is worse than not having any overcurrent protection installed and knowing you do not.