AC solar disconnect tap ahead of service disconnect

H

hhsting

Senior Member
Location
Glen bunie, md, us
Occupation
Junior plan reviewer
Following disconnect is used as tap ahead of service disconnect for solar install. Is the disconnect in below link suitable to use as service disconnect or not?

https://s3.us-east-1.amazonaws.com/rempdfbucket-prd/pdf/pds/US/en/Schneider%20Electric_QO-Load-Centers_QO24L70S.pdf?response-content-disposition=attachment%3Bfilename%2A%3DUTF-8%27%27Schneider%2520Electric_QO-Load-Centers_QO24L70S.pdf&AWSAccessKeyId=ASIASDDQ2UUV5KW6KUIQ&Signature=MjbMTiax9s9rOTXdzHF5XcTCdGM%3D&x-amz-security-token=IQoJb3JpZ2luX2VjEKb%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEaCXVzLWVhc3QtMSJGMEQCIHhDE6MfhSuOOsNKqMhF95HXDdloK1zAPqW4KnuZcFFrAiBaZUSfkyv789k67yFgFQw1FrRx7%2BTUTNuMiP27LbQVeSr%2BAghfEAAaDDE0NDExODAzMTY1OSIMT0hcU1vELsVPuzRjKtsCgGQf%2FyrZN0iE54dO7wbxWajYTHGR%2FZymPC0mNbgF06qck1MSEu8HrV3PxmQN%2Bd%2BRmmUPYQQcOQpYBg%2Ba11rsgcBapAtU1gs44p%2FUOC8Egi62UD8NkHNpnPbmSutnagSsGmN5lceHapy0Gv4bZGdTqwem%2Fu%2BGUY01Boq3EiAipzgO0hilzskL8fhuFEJWqfeW%2BfzLLAaXYCGs82WdeAg26%2FqoJYRl4akA00Di0%2BaGLfiVMFpLcnCBsE3p8jcDm44mZBt3b6uuTs1oFw%2FKXtTz4RZI3YkbcTaKZhsSS2KHBtFkQ%2FpWvsuDNFnKkoo5LVO%2BFGHW9Gyjf9sH7GbLUxFfWbc8xsFzW%2FAZbGtdXI3N0aB89DmtLw8CHwvsBN4kbXiWoqhf1SRZBkqGohsUcyAK8yat06rGmPkwNX1X26Qzej9a0%2BOKQjGJq0mtmfq8EkCkGdfv%2BO%2FqhIwS%2BW4w%2B62iwQY6nwHx%2FdmROQdlXtsBqzQdrO4zYehzJWMl408Ro12yZn%2FX%2F%2FHZMD%2Bf0Q3iWSw%2FyNKDIKzbO7x3XNK%2Fn%2BteL5By6dkfQXeeQ0dI8ef8To7JiM1ttgF%2FJL6sEnDSoQUrvpV9WHYGa0Adr5usszHawfycEzsq%2BL2JIT7z833%2F8oqBvPK8WtfRkY%2FakWyk7Vp8hsFBLDql56AFJFBxsq4%2B6ERoTDU%3D&Expires=1747534503
 
hhsting said:
Following disconnect is used as tap ahead of service disconnect for solar install. Is the disconnect in below link suitable to use as service disconnect or not?

https://s3.us-east-1.amazonaws.com/rempdfbucket-prd/pdf/pds/US/en/Schneider%20Electric_QO-Load-Centers_QO24L70S.pdf?response-content-disposition=attachment%3Bfilename%2A%3DUTF-8%27%27Schneider%2520Electric_QO-Load-Centers_QO24L70S.pdf&AWSAccessKeyId=ASIASDDQ2UUV5KW6KUIQ&Signature=MjbMTiax9s9rOTXdzHF5XcTCdGM%3D&x-amz-security-token=IQoJb3JpZ2luX2VjEKb%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEaCXVzLWVhc3QtMSJGMEQCIHhDE6MfhSuOOsNKqMhF95HXDdloK1zAPqW4KnuZcFFrAiBaZUSfkyv789k67yFgFQw1FrRx7%2BTUTNuMiP27LbQVeSr%2BAghfEAAaDDE0NDExODAzMTY1OSIMT0hcU1vELsVPuzRjKtsCgGQf%2FyrZN0iE54dO7wbxWajYTHGR%2FZymPC0mNbgF06qck1MSEu8HrV3PxmQN%2Bd%2BRmmUPYQQcOQpYBg%2Ba11rsgcBapAtU1gs44p%2FUOC8Egi62UD8NkHNpnPbmSutnagSsGmN5lceHapy0Gv4bZGdTqwem%2Fu%2BGUY01Boq3EiAipzgO0hilzskL8fhuFEJWqfeW%2BfzLLAaXYCGs82WdeAg26%2FqoJYRl4akA00Di0%2BaGLfiVMFpLcnCBsE3p8jcDm44mZBt3b6uuTs1oFw%2FKXtTz4RZI3YkbcTaKZhsSS2KHBtFkQ%2FpWvsuDNFnKkoo5LVO%2BFGHW9Gyjf9sH7GbLUxFfWbc8xsFzW%2FAZbGtdXI3N0aB89DmtLw8CHwvsBN4kbXiWoqhf1SRZBkqGohsUcyAK8yat06rGmPkwNX1X26Qzej9a0%2BOKQjGJq0mtmfq8EkCkGdfv%2BO%2FqhIwS%2BW4w%2B62iwQY6nwHx%2FdmROQdlXtsBqzQdrO4zYehzJWMl408Ro12yZn%2FX%2F%2FHZMD%2Bf0Q3iWSw%2FyNKDIKzbO7x3XNK%2Fn%2BteL5By6dkfQXeeQ0dI8ef8To7JiM1ttgF%2FJL6sEnDSoQUrvpV9WHYGa0Adr5usszHawfycEzsq%2BL2JIT7z833%2F8oqBvPK8WtfRkY%2FakWyk7Vp8hsFBLDql56AFJFBxsq4%2B6ERoTDU%3D&Expires=1747534503
Click to expand...

Here is the link to disconnect
www.se.com

QO24L70S - Load center, QO, 1 phase, 2 spaces, 4 circuits, 70A fixed main lugs, NEMA1, surface cover | Schneider Electric USA

Schneider Electric USA. QO24L70S - Load center, QO, 1 phase, 2 spaces, 4 circuits, 70A fixed main lugs, NEMA1, surface cover.
www.se.com www.se.com


Sent from my iPhone using Tapatalk
 
See https://www.se.com/us/en/faqs/FA272365/

My conclusion is that QO24L70S is SUSE, as it is not on the list of exceptions in above. Would be a bit tricky to pull off:

I don't see a service entrance barrier in Square D's catalog for the main lugs on that panel, so you'd have to backfeed the breaker and use the barrier for backfed breakers, PKSB1QOBF. Then the backfed breaker would need a hold down kit, which I believe would be PK2MB, although QO24L70S is not listed in the catalog as one of the panels for which that product fits, so it would be necessary to verify that it is compatible.

Cheers, Wayne
 
wwhitney said:
See https://www.se.com/us/en/faqs/FA272365/

My conclusion is that QO24L70S is SUSE, as it is not on the list of exceptions in above. Would be a bit tricky to pull off:

I don't see a service entrance barrier in Square D's catalog for the main lugs on that panel, so you'd have to backfeed the breaker and use the barrier for backfed breakers, PKSB1QOBF. Then the backfed breaker would need a hold down kit, which I believe would be PK2MB, although QO24L70S is not listed in the catalog as one of the panels for which that product fits, so it would be necessary to verify that it is compatible.

Cheers, Wayne
Click to expand...

I dont follow your post this is disconnect not panelboard. Also your post it says yea Q024L70S SUSE but then says need to backfeed breaker


Sent from my iPhone using Tapatalk
 
hhsting said:
this is disconnect not panelboard.
Click to expand...
Sure, but it's a panelboard being used as a service disconnect, not a problem.

hhsting said:
Also your post it says yea Q024L70S SUSE but then says need to backfeed breaker
Click to expand...
I don't believe there's any prohibition on using a backfed breaker for a service disconnect. But there is a requirement to guard the line side connections on the service disconnect. Unless Square D makes a guard for the line side lugs on QO24L70S, which I didn't see it in their catalog, the only guarding option from them is to use their guard for the terminals on a backfed breaker, PKSB1QOBF.

Anyway, if you want a more knowledgeable answer, you'll probably have to call Square D technical support, they have been pretty helpful in the past.

Cheers, Wayne
 
wwhitney said:
Sure, but it's a panelboard being used as a service disconnect, not a problem.


I don't believe there's any prohibition on using a backfed breaker for a service disconnect. But there is a requirement to guard the line side connections on the service disconnect. Unless Square D makes a guard for the line side lugs on QO24L70S, which I didn't see it in their catalog, the only guarding option from them is to use their guard for the terminals on a backfed breaker, PKSB1QOBF.

Anyway, if you want a more knowledgeable answer, you'll probably have to call Square D technical support, they have been pretty helpful in the past.

Cheers, Wayne
Click to expand...

In my case it is connected on the line side of main service disconnect means.

Do I need backfeed breaker? I thought requirement in my case is disconnect needs to be suitable for service disconnecting means?
 
hhsting said:
In my case it is connected on the line side of main service disconnect means.
Click to expand...
Yes, I understand. That makes it a second service disconnect.

hhsting said:
I thought requirement in my case is disconnect needs to be suitable for service disconnecting means?
Click to expand...
Indeed, and if you read the reference in my first post, it states that with a few exceptions "All QO single and three phase and HOM load centers are marked as "Suitable for use as Service Equipment" if equipped with integral main breaker or when not more than six disconnecting means are provided." The QO24L70S was not on the list of exceptions, and with only 2 spaces, it obviously has less than six disconnecting means. [The 2020 NEC add a limit of one disconnecting means per enclosure, which the proposed install complies with.]

If you stick a 2 pole breaker into QO24L70S (which will fill all the spaces), then the assembly will have two sets of lugs, the lugs on the breaker itself, and the lugs that part of the panelboard. If that breaker is the service disconnect, then the lugs on which the service conductors land need to be guarded after the connection is made. Functionally, the service conductors can go onto either set of lugs. But if Square D only makes a guard for the lugs on the breaker, and does not make one for the lugs on the panelboard, then the service conductors have to land on the lugs on the breaker. Which is commonly referred to as "backfeeding" the breaker.

Cheers, Wayne
 
wwhitney said:
Yes, I understand. That makes it a second service disconnect.


Indeed, and if you read the reference in my first post, it states that with a few exceptions "All QO single and three phase and HOM load centers are marked as "Suitable for use as Service Equipment" if equipped with integral main breaker or when not more than six disconnecting means are provided." The QO24L70S was not on the list of exceptions, and with only 2 spaces, it obviously has less than six disconnecting means. [The 2020 NEC add a limit of one disconnecting means per enclosure, which the proposed install complies with.]

If you stick a 2 pole breaker into QO24L70S (which will fill all the spaces), then the assembly will have two sets of lugs, the lugs on the breaker itself, and the lugs that part of the panelboard. If that breaker is the service disconnect, then the lugs on which the service conductors land need to be guarded after the connection is made. Functionally, the service conductors can go onto either set of lugs. But if Square D only makes a guard for the lugs on the breaker, and does not make one for the lugs on the panelboard, then the service conductors have to land on the lugs on the breaker. Which is commonly referred to as "backfeeding" the breaker.

Cheers, Wayne
Click to expand...
They need to update the information, as starting with the 2020 you can no longer do that.
 
don_resqcapt19 said:
They need to update the information, as starting with the 2020 you can no longer do that.
Click to expand...
True. But in this case a non-issue, as the panelboard has only two spaces.

One thing I didn't look into was whether QO24L70S has provisions for a main bonding jumper, e.g. a screw. If not, I think it can't really be SUSE?

Cheers, Wayne
 
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