Safety Switch for Restaurant

[Harry V. McBride, III]

Okay guys! This is the deal. This restaurant has a safety switch service entrance with two 200 amp fuses and a 125 amp fuse. There are four, count them four, sub-panels coming off this safety switch. Two 150 amp sub-panels and two 100 amp sub-panels. Question is: Is this safety switch entrance enough for the four sub-panels? Also, should I recommend a evaluation by a licensed electrical contractor? Here are some photos.

[Marc D. Shunk]

In a commercial occupancy, it is quite common to have lots of panels hanging off what might seem like a small service. They do this to simply get more "spaces". Without doing a demand load calc, there's no way to know if the service size is adequate. If the fuses don't blow in the disco, that's one half-shod way to know.

I'm a bit concerned that the old Penetrox has heated run down all over the fuse holder terminal wipers and hardened. This can present a problem for reliable refusing of the disconnect, should it become necessary in the future.


If this is a 3 phase service, they likely only have one 3phase panel and 3 single phase panels. This is my best guess, based on the fusing arrangement. Either that, or they've fused the neutral. Hard to say at first blush.

[Harry V. McBride, III]

Yes, Marc it is a 3 phase service. As you see in the fourth picture there are two sub-panels located near the safety switch. There are two additional 100 amp sub-panels. The fifth picture is the panel to the right of the safety switch. This panel looks like a mess. I didn't see any double taps and the wiring appeared to be sized properly but there are multiple wire splices and I can't determine were they are all going. Shouldn't I just defer to a licensed electrician to evaluate this whole system just to play it safe.

[Paul W. Abernathy]

Harry,

I am with Marc on this one....In the 5th picture I simply can't determine the location of the "Grounded" conductor through all that mess. While it is a REACH the cross section wire requirements seem to be a mess here.....I would venture to say they exceed the minimums.

I would not be against having this looked at....I would LOVE to dig into it personally and see if the remote panels are done properly and even do a load calc on it myself.....

Now as marc said if this was a 200A service with 3 phase....and they sized down the one to a 125A fuse...I would say either someone did not do a load calc or they just guessed....in the 4th picture the center conductor is quite small compared to the others....typically in a 3 phase setup they are equally sized unless they know something on the count we dont.

[Speedy Petey]

Marc, do you really think it heated up and dripped. It looks to me to just be a messy job of slathering noalox on the fuse holders.

The reason for the smaller fuse is possibly becasue this is a delta service with a high leg and the center phase is not getting nearly the load of the other two.
Why the smaller fuse? Who knows??? There is no reason for it.
Maybe that is all they had at one time to replace a 200?

[Doug Edwards, CMI]

To do a commercial inspection I would have a sparkie on retainer and on the job with me to do that portion of the job while I occupied myself with all the other pressing issues. It would be worth whatever his hourly rates are just to have him or her there.

[Pierre Belarge]

Check out the lugs that have been installed...nice

I would bet that the 200 amp fuses replaced two other bad 125 amp fuses...look at the size of the conductors.

Did I mention the lugs....

[Speedy Petey]

You know what I find strange. Look in the third pic. The service condcutors do seem to be large enough for 200 amps, 3/0cu, but does the center condcutor look smaller?

[Paul W. Abernathy]

Originally Posted by Speedy Petey

You know what I find strange. Look in the third pic. The service condcutors do seem to be large enough for 200 amps, 3/0cu, but does the center condcutor look smaller?

yeah....thats what i was talking about....unless they know something on the CALC side we don't it is usually strange even in a delta config to do this as you notice that most of the panels being used as 120/240 panels ....now we know that quite possibly the center could be the high leg and well...they are just not using it.........at all thus the smaller size......

just an old strange setup I guess

[Greg Fretwell]

If the high leg has a lower ampacity that should be reflected in the fuse size.
I agree in 3p center delta it is common to have a lot higher load on the center tapped (120/240) winding. That will be a bigger transformer. The high leg will only serve the 3p loads. If this is only using 2 transformers it is important not to connect any L/N load to the high leg.