Generator Question

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splinetto

Senior Member
Location
Missouri
I wanted to know if this installation is correct....200 amp main breaker panel feeds a 200a service rated ATS with 100a feeder and then onto a 100a subpanel...from the 15KW ?generator (65amp breaker) with #6's to the ATS...
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
sounds correct if your 100 amp feeder has 100 amp OCP.
(that wasn't 100% clear to me)
 

splinetto

Senior Member
Location
Missouri
augie47 said:
sounds correct if your 100 amp feeder has 100 amp OCP.
(that wasn't 100% clear to me)
Yes the feeder is on a 100a OCPD it just seems odd that a 100a wire is landed on a 200a breaker in the ATS...and the lugs that the # 6's will land on a lug that looks large for a # 6 , but I didnt look that close
 

aksparky

Member
Since the 08 code change if we are using an automatic transfer and do not have a genset sized to the breaker feeding the subpanel then we have to submit a load calc proving that the genset will handle the load to which it is connected, its usually first thing the inspector asks. 702.5 (2) a.
Just curious if others have to provide this to their inspectors.
 

Rich R

Senior Member
Not sure if this is something you installed already or planning to install but the 'Service rated ATS is not needed in this setup. ( Service rated ats switches are double the price of non service rated.

also the wire is too small for a 65 amp breaker unless you are using a special insulation type for the #6's.

Generally if it is a guardian type unit, the wire that comes with it is rated for 65 amps


...AKSparky , we have to submit a load calc on any auto transfer switch whether it matches the main size or not. This is submitted with the drawings for permit approval
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Rich R said:
also the wire is too small for a 65 amp breaker unless you are using a special insulation type for the #6's.

unless it's NM, why ?
 

jwelectric

Senior Member
Location
North Carolina
Rich R said:
Not sure if this is something you installed already or planning to install but the 'Service rated ATS is not needed in this setup. ( Service rated ats switches are double the price of non service rated.
It could be that the ATS is rated as service equipment for the disconnect required by 225.30 through 225.39


Rich R said:
also the wire is too small for a 65 amp breaker unless you are using a special insulation type for the #6's.
augie47 said:
unless it's NM, why ?
I agree if using SE cable it is too small as outlined in 338.10(B)(4)(a)

Rich R said:
...AKSparky , we have to submit a load calc on any auto transfer switch whether it matches the main size or not. This is submitted with the drawings for permit approval
and rightly so
 
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