ECN Forum Forums General Topics of the Trade General Discussion Area Sub-Panel Trade Practices?

As all of you probably guessed, a recent customer request got me thinking about this issue.

The customer wants a baseboard heater added to a cold bedroom. Fair enough - but for the fact that the original panel was pretty well filled from the day the house was built. Add a hot tub, add a sun room, etc. .... and you wind up with a 20-space panel that has 36 circuits in it. Thank heaven for twin breakers!

So, naturally, I'll be cleaning up that crowded panel as part of the job.

It's a bit of a challenge to find a sub-panel that will 'look right.' If you do, the knock-outs are sure to not line up. If the new panel is the same size box as the main panel ... that's a LOT of breaker spaces!

I think we can agree that a tiny 6-space box hanging off the side of a full-size panel just lokks "diy."

1-I always allow for expansion. Then I'm really nice and professional,so I AM the one who comes back.:)

2- Stick with whats there,if available.
I line up the top.

Except for the last one I did.
Matched the top of the tubs,in a basement.Installed the covers,original had a surface cover,mine was flush.
Man!!!! That 1/2 inch difference made the job look like crap! (in my eye.)

I'm the same way. In many cases, an offset nipple will offer enough leeway to accommodate inconsistent knockouts. I also agree that the cost difference between a tiny panel and a full-sized one is negligible in the grand scheme of things.

Unless the original panel is a Zinsco or FPE, I always try to use the same brand/style.

What if you were relying on series ratings to provide protection? How would 10 ka Cutler hammer breakers work with Square D ahead? The rules for series ratings require both breakers are actually tested in series. Lots of commercial panels have greater than 10,000 amp fault currents available. We have services where fault currents are way over 65 ka and some that are considered 100ka.

At the risk of this thread going far afield, IMO the 'series rating' clatrap has been blown way out of proportion, and is little more than an aggressively pushed sales tool. (It lets them claim 'exclusivre' rights to an entire job.)

Yet, if that's a concern, you can avoid it by simply back-feeding a breaker in the new panel - or use a panel with a main breaker.

This project of mine is a case in point: the 'original' panel manufacturer technically doesn't exist anymore. Someone might make a fuss if they see a 'brand X' breaker in a 'brand Y' panel.

I sometimes wonder about these things and recall that Cutler hammer (wetinghouse) was the big lead on series ratings. Although I suppose the up over and down method was working most of the time there were rare problems where two breakers racing to trip and the lower rated breaker failed. We have a secondary network in part of our downtown and the fault currents are astronomical. I had seen more than a few upstream breakers win the race to trip with the local breaker welding closed or open. Never had a breaker blow up Yet.
What I thought was a great benefit was that it brought attention to the hazards associated with high fault currents.

As for maker A breakers in maker b panels I know some breakers fit and some are approved and I know the difference and hope my staff do too.

Talk about series rating, I have seen a strip mall where in the diner, there was a 100 amp. service panel that was fed from a 100 amp disconnect next door in the liqueur store (LS). The diner's panel was a Fed-Pac and the LS was a Square D. There was a piece of faulty equipment in the diner which was tripping the main in the LStore. The big problem was the Diner oped at 6:00 AM and the store at 10:30 AM. So when the breaker tripped, The diner was without power to the store owner came in. The first few times it tripped, the store owner would come in and open early for the diner, after 5-10 times the store owner wouldn't come in early anymore.

I've encountered that situation once or twice in commercial / industrial rentals, and as far as I'm concerned that's a great example of really bad design.

I note that the NEC requires breaker access for residences, unless there is 24/7 maintenance response available.

Otherwise, (memory of bad experience intrudes here), having seen this situation from evry possible angle, I have to say to the tenants: "your cheap-skate landlord cobbled together the barest minimum HE needed to extract the maximum rental income; your only solution is to vote with your feet, and spend serious money yourself to prepare the new location for your use."

Another aspect of the issue is the refusal of the customer to admit that they're doing something wrong- that either they're pushing things too close to the margins, or there's something wrong with their equipment. From their perspective, "FPE is better than Square D because it does NOT trip."

Neither does a penny.

Harold
That is a bad distribution design for sure.
A couple of years ago a local office building had an emergency panel upgrade. The original panel had all fused disconnects for the various emergency panels. All of the loads were coordinated to be sure the lowest rated fuse blew 1st.
When I went to inspect the replacement panel which was all breakers I discovered the panel breakers were series rated which I immediately rejected as a branch breaker could take out the main which I also made them remove once we established the fuse ahead was better coordinated and could not be coordinated with the EM panel main breaker.
The engineer said he ordered a coordinated CDP but of course did not verify the delivered breakers met the design. The wholesaler and the electrical contractor might have substituted the lower rated breakers as they were pretty pricey to have a coordinated system at the fault levels in this building.
Series rated systems can save on installation costs but coordinated systems give much more reliable protection or at least are more likely to leave the other unfaulted loads working. Never allow it on a life safety system.