Replacement of Existing Chiller System

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legato

Member
Location
Mountain View, CA
Occupation
Consulting Electrical Engineer
Hi All,

I'm involved what I understand to be a infrastructure upgrade type of job where an existing chiller system is being replaced with new.

The existing system is an "A" & "B" system and will be replaced with a rooftop chiller that I am going to say is roughly about the same in terms of connected load for argument sake.

I'd like to know if we are required to have the contractor do a fault study, coordination study, and arc flash as we are modifying an existing electrical distribution.

The existing MCC that serves the mechanical is an OLD GE board that I want to say was built / installed in the 60's.

Thanks in advance!
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
...
I'd like to know if we are required to have the contractor do a fault study, coordination study, and arc flash as we are modifying an existing electrical distribution. ...
While it may be a good idea to look at those things, none of them are required by the NEC.
 

lielec11

Senior Member
Location
Charlotte, NC
While it may be a good idea to look at those things, none of them are required by the NEC.

If you're the engineer I would suggest bringing this to the attention of your client to see if you could get more work out of it (especially since the panel is from the 60's, this could be dangerous). We do studies like this all the time and they are good work.
 

legato

Member
Location
Mountain View, CA
Occupation
Consulting Electrical Engineer
Thanks all for the responses.

We are generating bridging documents that will give a design-build contractor the scope of work to bid and install necessary electrical infrastructure for the new chiller system.

I am just making sure we can create an obvious line in the sand as to how far this replacement project goes.

The client is aware of this and would like to do a full blown study after the fact, which I am guessing we may be contracted to do... :)

If you're the engineer I would suggest bringing this to the attention of your client to see if you could get more work out of it (especially since the panel is from the 60's, this could be dangerous). We do studies like this all the time and they are good work.
 

legato

Member
Location
Mountain View, CA
Occupation
Consulting Electrical Engineer
Hi Ron,

Is "THEY" the electrical contractor who does the installation?

So if we note on our BOD / drawings to have them verify the available fault current, we should be OK?

They are required to calculate available fault current at the new chiller starter to ensure it is specified with the correct short circuit rating.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Hi Don,

The Chiller is by the Mech Contractor and all new electrical breaker buckets would be the Elec. Contractor.
You have to know the available fault current before you buy the equipment. You many have to hire someone to get that information before you put the project out for bid.
 
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