Square D Panel

[electricman2]

Thought this panel might be interesting enough to post a picture. It serves a recreation center building where I have a job to relocate a 40A range circuit and add two 20A SA circuits. It is a Square D QON-420. 120/208 3phase with 20 spaces. Building service is 120/240 single phase. The 2 pole breaker at the bottom uses spaces 17-20 and serves as a back fed main. It is on phases A and C. There is a jumper at the top that ties phase B to phase C. I don?t know of anything that makes this illegal but it is something I?ve not seen. Anyone seen anything like this?

 

[barbeer]

I have seen alot of stuff like this.....that doesn't or didn't make it right!

 

[ron]

Is the panel rated for 120/240 or 120/208?

 

[SEO]

Back-fed breaker 408.36 (F).Non CTL rated circuit breakers.

 

[jim dungar]

Is the panel rated for 120/240 or 120/208?

A QO-420 was rated for 240V maximum (the number QON-420 is that of the interior only).

 

[Fishin-trician]

try putting an amprobe on the neutral main wire to see how unbalanced the load is. could use a panel change out for sure.:roll:

 

[Cow]

try putting an amprobe on the neutral main wire to see how unbalanced the load is.

Why? I think you misunderstood, he's not using 2 legs of a 3-phase service.

 

[benaround]

Why? I think you misunderstood, he's not using 2 legs of a 3-phase service.

I read he is using 2 phases 1 on A and 1 on C , then on top there is a jumper

from C to B . The panel is 3ph the service is 1ph. Checking the neutral is not

a bad idea, imo.

 

[norcal]

Back-fed breaker 408.36 (F).Non CTL rated circuit breakers.

That panel predates 408.36(F) (it was 384-16(f) in the 1990 NEC for the 1st time) so can that section be used?

 

[fishin' electrician]

A 20 space 3? panel :-?

 

[ItsHot]

Looks good!:grin:

 

[jim dungar]

Back-fed breaker 408.36 (F).Non CTL rated circuit breakers.

I estimate this panel to be from the early 1960's (there are breakers without the Visi-Trip feature). While they had an equivalent to CTL in those days, 3-phase QO panels have never been rated for tandem breakers.

 

[bikeindy]

Thats todays winner, I wouldn't do any work on that panel tell them it needs to be changed and collect the money.

 

[SEO]

That panel predates 408.36(F) (it was 384-16(f) in the 1990 NEC for the 1st time) so can that section be used?

Section 384-16(f) was a change for the 1990 NEC . I agree that section 408.36 (F) would be a wrong call for pre 1990 code . This section also was 384-16 (G) in 1999 NEC ,section408.16 (F) 2002 NEC, 408.36 (F) 2005 NEC, an 408.36 (D) 2008 NEC. What section will it be in 2011? Whatever code that was in effect at the time of installation would apply.

 

[sparky723]

Ugly

Ugly

I agree with bikeindy. Tell them the BEST ( and probably) the safest thing to do is to tell the customer is to let you completely demo the old panel and replace it with a new service. Ugly stuff like that needs to be wiped off the planet...sparky723

 

[electricman2]

I agree with bikeindy. Tell them the BEST ( and probably) the safest thing to do is to tell the customer is to let you completely demo the old panel and replace it with a new service. Ugly stuff like that needs to be wiped off the planet...sparky723

Easy said. Customer wants two SA circuits, nothing more. We put in a 2 pole 20A, ran 12-3 MC and put the cover back on.:wink:

 

[acrwc10]

Easy said. Customer wants two SA circuits, nothing more. We put in a 2 pole 20A, ran 12-3 MC and put the cover back on.:wink:

I know it is not enforceable but. 80.9(c) allows just the addition of the circuits without changing the panel. Still "YUK" did you atleast try to get them to go for an upgrade ? I think it would have been a good idea.