RTU Service Disconnects and Conduit Life Cycle

[Dan Keyack]

As a building engineer for retail stores, one of the biggest abuses of electrical safety is related to roof top air conditioning unit disconnects and liquittite conduit as it relates to unit replacement. Time after time, I have seen contractors for our stores changed out units and have been reusing rusty disconnects, and cracked or split liquid tite conduit (whips) on the roof. Does anyone know of a published article that relates to the average life cycle of rooftop electrical service components that service RTUs as if related to electrical safety including arc flash potential due to old age? As some general life cycle safety discussions have been discussed, if these electrical components will not last as long as the replacement unit, they should be replaced during the installation.
:?

 

[iwire]

Why not just put replacement in the job requirements?

 

[kwired]

As a building engineer for retail stores, one of the biggest abuses of electrical safety is related to roof top air conditioning unit disconnects and liquittite conduit as it relates to unit replacement. Time after time, I have seen contractors for our stores changed out units and have been reusing rusty disconnects, and cracked or split liquid tite conduit (whips) on the roof. Does anyone know of a published article that relates to the average life cycle of rooftop electrical service components that service RTUs as if related to electrical safety including arc flash potential due to old age? As some general life cycle safety discussions have been discussed, if these electrical components will not last as long as the replacement unit, they should be replaced during the installation.
:?

The disconnect and flex maybe will last longer then one HVAC unit - but problem may be this is the 4th unit it has supplied?

 

[Jraef]

The "arc flash potential due to old age" might possibly be an angle, if your facilities are using NFPA 70E as the basis of your Electrical Safety Program. There is a clause in the wording of how some tasks, such as using switches, without the need for PPE is contingent on the equipments being properly installed and maintained per manufactures instructions, and in good working condition without evidence of damage or compromised integrity (words to that effect).

But really, that would still point back to what iwire said, because it would at best be the JUSTIFICATION for writing a job specification that disallows the use of old equipment. Here's the thing about that. If 3 contractors are bidding on the work, and one of them is going to re-use the service equipment because there is nothing saying he can't, then he is likely to be given the job. So the others have to protect themselves from that and do the same. You can cry the blues after the fact and point to anything ambiguous that makes you feel better about your outrage, but really, its the fault of an inadequte job spec. But if your SPECIFICATION calls out for new service equipment and "whips", then everyone is on an even playing field. So really, that's the way to approach it. If you get push-back from bean counters over increasing the cost of replacing an RTU, that's when you pull out the wording in NFPA 70E. If they still balk, pull out the OSHA book and point out how, if someone gets hurt later and it comes down to that being the issue, managers can be held criminally liable.

 

[sparkyrick]

Maybe, sometime in the future, the NEC will mandate that all RTU's have a built-in disconnect and have a decent point-of-entry for the conduit from underneath.

 

[ptonsparky]

I see a GFCI there, what the heck, I suppose you want milk with your cereal too?

I agree spec it, then make sure someone with authority to enforce the bid document inspects it. The AHJ in our area could care less what is spec'd as long as it meets code.

 

[qcroanoke]

I agree with Iwire and Jraef write it into the scope of work that disconnect and sealtite shall be replaced with new components.

 

[kwired]

Maybe, sometime in the future, the NEC will mandate that all RTU's have a built-in disconnect and have a decent point-of-entry for the conduit from underneath.

Or decent point of entry for most any other HVAC equipment, but I don't expect anything like that during my lifetime