Siemens MBR1 retaining clip

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richardmoore

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Can anyone tell me what a Siemens MBR1 retaining clip for a back-fed 100-amp main breaker looks like? Would its presence be obvious? I can't seem to find an image anywhere.

The 5 year-old Siemens 125-amp panel I inspected today had no issues other than it was back-fed through a 100-amp breaker (fine) and no matter how hard as I stared at it I could see no retaining screw, bolt, or clip.

Thanks in advance,
Richard Moore

[ March 17, 2005, 03:57 AM: Message edited by: richardmoore ]
 
Re: Siemens MBR1 retaining clip

Originally posted by jimwalker:
...Were you able to remove the breaker ?
Click to expand...
LOL...Nope, that goes beyond my job description. I'm just one of those "pain-in-the-*** " home inspectors.

There was definately no screw. All the Siemens info refers to a "MBR1 retaining clip", rather than a screw or bolt, for this use. With the deadfront removed I would assume that it would be easily visible but, to quote the little German from Laugh-in, I saw nothing!

Richard Moore

[ March 17, 2005, 07:03 AM: Message edited by: richardmoore ]
 
Re: Siemens MBR1 retaining clip

Richard,

The MBR1 retaining clip is subtle, in appearance, when installed, but it is obvious when one is looking for it and is somewhat familiar with the Siemens line.

The MBR1 is shown on page 1-33, left side middle. This is from the current Siemens Speedfax catalog circuit breaker accessories section.

The clip pivots into place as it installs and, once in position, is not reversible (unlike a screw). But, because the bus pan parts are plastic and can be deflected with a bit of carefully applied force, it is fairly simple to remove the clip-secured breaker.

Factory installed main breakers, in my experience, have the clip attatched by a rivet. The field installed clip floats until it snaps into place.

Edit typo - Al

[ March 17, 2005, 09:03 AM: Message edited by: al hildenbrand ]
 
Re: Siemens MBR1 retaining clip

Thanks Al,

It appears that you would see a piece of plastic projecting out from the terminal side. I just rechecked my photo and can't see anything extra.

Much appreciated,
Richard Moore
 
Re: Siemens MBR1 retaining clip

It appears that you would see a piece of plastic projecting out from the terminal side.
Click to expand...
Just to be clear about what you mean by "terminal side". . .

The little flag piece of plastic is visible on the end of the breaker directly over the center of the bus bars. This is the end of the breaker that the wires don't terminate to.

If the back fed breaker is butted to another breaker(s) on the other "side" of the panel, the plastic flag will be straight down in the crack between them.
 
Re: Siemens MBR1 retaining clip

There's no way to tell from this side of that camera lens that took your photo.

Careful examination with a good light source, and perhaps tipping back the 50 Amp 2-pole breaker slightly will be required to make the determination.
 
Re: Siemens MBR1 retaining clip

It's "spilt milk" now as I recommended an electrician take a look. It does seem dumb design that it's not more obvious.

Ah well...onwards.
Thanks, Richard
 
Re: Siemens MBR1 retaining clip

There is no clip installed there. You would see it, it is red. I also don't think you would be able to install a breaker in the opposite side of the panel.
 
Re: Siemens MBR1 retaining clip

I'll tell ya 2 things I do see...

1) An insulated grounded conductor from the feeder, which leads me to believe this is a sub panel fed with SER cable???

2) If it is a sub panel feeder, then what looks like #2AL is only good for 90amps???

The clip is red as electricmanscott describes, but it is not visible from the front. If you were to remove the 2-pole 50, you would see the retainer clip from that angle. I put one in a couple of months back, and I believe that a breaker could be installed opposite the main.

shortcircuit2
 
Re: Siemens MBR1 retaining clip

The tip of the "flag" on the MBR1 that emerges from the slot in the middle of the 100 A 2-pole will slip into a corresponding slot in the 50 A 2-pole. The two breakers will definitely mount correctly.

It is hard to see in this particular application.

Some of the MBR1s tjat I've installed have been gray, some red.
 
Re: Siemens MBR1 retaining clip

The retaining clip that I have seen is a cheap piece of red plastic and it DOES NOT WORK!
 
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