Emerg. Generator breaker size - Riser check

[Designer69]

My main question is on the E/G circuit breaker size(s) for the attached riser diagram. I am not sure if I should make them the same size as the breakers feeding the normal side of the ATS.

The C-2 and C-3 cables are sized for the connected loads (x 1.25%) of the downstream panels.

Also, an ovarall sanity check on the riser is appreciated. The emergency branch only has 1KVA worth of emergency lights but still required since emergency lights need emergency branch/ATS.

better pic here: https://ibb.co/iuHMoT



Thank You

 

[Ingenieur]

without knowing conductor size it looks ok
why such a large genset 50 kva for 14 load?

 

[Designer69]

without knowing conductor size it looks ok
why such a large genset 50 kva for 14 load?

Thank you! I used the generator sizing software from Kohler and that is what it came up with. It is natural gas so maybe not the same power as diesel? Initially I thought we were going to provide diesel and the same software picked only a 15KW.

Any thoughts if the emergency branch even applies to a type R-2 occupancy as well? I'm not sure if these are more meant for healthcare facilities and if only a stand-by branch is sufficient for type R-2.

 

[augie47]

I don';t know if the diagram is "symbolic" or factual. Since the generator and service is shown a 120/240, I assume the load is 120/240. If, as drawn, the 12.6 kw load is on a SP 120 breaker, the breaker is undersized.
Your EGC would be sized by the breaker on the circuiton which they are installed.

 

[Designer69]

I don';t know if the diagram is "symbolic" or factual. Since the generator and service is shown a 120/240, I assume the load is 120/240. If, as drawn, the 12.6 kw load is on a SP 120 breaker, the breaker is undersized.
Your EGC would be sized by the breaker on the circuiton which they are installed.

Thank you for the info.

It's a 120/240 1-PH system. Panelboard SB-1 has 12.6 KVA of heating loads which I determined are continuous. So.. 12.6KVA / 240 = 52.5A * 1.25 = 65A. Therefore I picked a 70A breaker for this "stand-by" branch. The emerg. branch is similar, though only 1KVA of LED lighting.

I am not sure if there are any other special requirements for the E/G breakers or if they too may be sized per the above methodology. Also, I am not sure what you mean by "load is on a SP 120 breaker".

Thanks

 

[Designer69]

FYI to anyone interested - Regarding whether a separate emergency branch is required for type R-2 occupancies.

I believe I confirmed the answer to be yes and my reasoning is a follows:

-IBC and state bldg. codes say Emergency power for egress illumination is required for corridors/areas that require at least 2 exits/means of egress. (1008.3)
-Life safety code & IBC specifiy that R-2 occupancies must have at least two means of egress. (IBC 1006.2.1. - Life Safety 28.2.4.1)

 

[rlundsrud]

Well I have absolutely no codes to back this up, if the egress lighting has battery backup built into it wouldn't that eliminate the requirement for emergency power to feed it?

 

[drktmplr12]

Well I have absolutely no codes to back this up, if the egress lighting has battery backup built into it wouldn't that eliminate the requirement for emergency power to feed it?

this is the primary reason battery powered emergency lights are available. however the lights must be frequently tested to ensure batteries are functional and will supply the requisite time period of egress lighting. not sure of the specific requirements of testing (frequency, how to document it has been tested). this information is probably found in some chapter of life safety code.

 

[Designer69]

yes if you have unit equipment with battery packs then you definitely don't need any emergency branch.

However, the owner for this occupancy does not want the ugly unit equipment and also hates the testing involved so therefore an emergency generator is used.

 

[augie47]

yes if you have unit equipment with battery packs then you definitely don't need any emergency branch.

However, the owner for this occupancy does not want the ugly unit equipment and also hates the testing involved so therefore an emergency generator is used.

as if generators don't require testing/maintenance LOL

 

[drktmplr12]

yes if you have unit equipment with battery packs then you definitely don't need any emergency branch.

However, the owner for this occupancy does not want the ugly unit equipment and also hates the testing involved so therefore an emergency generator is used.

for this to be compliant, the emergency power system must be activated within 10 seconds of losing power.