mstrlucky74
Senior Member
- Location
- NJ
Engineer asking us to remove 100A MCB in panel and make panel MLO. Is that a PIA? What's involved? Thanks.
MCB TO MLO
- Thread starter mstrlucky74
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
If it is just a panelboard why would you need to have the gear rep price it up?
I think most times it is pretty simple to remove the MCB in most PBs but you also have to close the hole where it used to be.
mstrlucky74
Senior Member
- Location
- NJ
You have to attach the main lugs to the phase buses, no?
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
you can usually just buy the pieces out of a catalog. the point i was trying to make was it is not real hard to do yourself.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Can be as simple as removing a 3 pole circuit breaker, bolting on 3 terminals and installing blanks over the 3 slots. Why is he requesting this in the first place?
mstrlucky74
Senior Member
- Location
- NJ
Not sure.
mstrlucky74
Senior Member
- Location
- NJ
What hole?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
The hole in the cover or dead front where the main breaker was.
kwired
Electron manager
- Location
- NE Nebraska
How easy this may be depends on design of the gear you have.
A lot of newer equipment is more "modular" than some old equipment was and may be pretty simple to make this change.
Going from main lug only to main breaker can be more difficult especially if the cabinet needs to be longer to house the main breaker.
Many gear manufacturers will sell you complete new panel, cabinet, breakers and needed accessories for less $$ than they would sell you just a few of the components alone. Keep that in mind when deciding what to do.
A lot of newer equipment is more "modular" than some old equipment was and may be pretty simple to make this change.
Going from main lug only to main breaker can be more difficult especially if the cabinet needs to be longer to house the main breaker.
Many gear manufacturers will sell you complete new panel, cabinet, breakers and needed accessories for less $$ than they would sell you just a few of the components alone. Keep that in mind when deciding what to do.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
The others have addressed the "how to." I will speak to the "whether or not to." Who wants this done and why? More to the point, is there a breaker upstream of this panel that serves as the overcurrent protection for the panel and its feeder?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Once I finished a job that someone else started. They had ordered the 4 250 amp panelboards with main breakers. They were subs and not fed by taps or tranny's so there was no need for the mains. I took them out, added lugs, and used the breakers in the main distribution board which hadn't been ordered yet. Saved the client $1500 I think. But if you don't have specific repurpose for the breaker, it's probably not worth taking out.
mstrlucky74
Senior Member
- Location
- NJ
The panel in question was being fed via 45kva xfrmr. Now the 45kva xfrmr is feeding a new panel and a 3P 100A breaker in the new panel is now feeding this panel in question. Not sure if the pick is legible. The panels with the square and #1 are the one swapping from MCB to MLO.
Attachments
- Location
- New Jersey
- Occupation
- Journeyman Electrician
If I'm reading your drawing correctly there is no reason to remove the existing main CB but if that is what they want and they're paying you for it then just do it.
kwired
Electron manager
- Location
- NE Nebraska
Apparently your main distribution board was able to accept those breakers, not always the case. Even if the same breakers you may possibly still need some additional hardware to install them such as bus links and fasteners that were designed/tested for the application vs common fasteners.
Not that you can't get such hardware, but these manufacturers seem to like to honk you hard on such items if a stand alone purchase, yet practically give a lot of stuff away in comparison when you order the entire panel and accessories on one order.
Need 1/2 dozen I-line breakers, maybe even as little as 3 or 4? Might get a small main lug panel plus your 3-6 breakers for less cost than if you purchased just the 3-6 breakers. That is how they like to sell this kind of product.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Yup. In this case I just ordered the MDP with 2 breakers and 4 "prepared spaces" for the ones I took out, so it came with all the correct bussing and fingers. I got hit a few hundred for the main lugs kits but it was still well worth it. The breakers had plenty of AIC, which could often be a deal breaker in such a situation.
bcorps
Member
- Location
- Evansville, IN
- Occupation
- Engineer
I found this out recently when reviewing shop drawings for a job. I had called for replacing a bunch of circuit breakers in an NF panel. The shops showed a whole new panel. Naturally, I was a bit concerned that something was going on that I knew nothing about, but the contractor told me buying a whole new panel, new breakers and all, was significantly less than just buying the breakers.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
kwired
Electron manager
- Location
- NE Nebraska
I can also buy pump panels for less than I can buy the NEMA starter they house.
And yes for the NF breakers, to get best deal just purchase a main lug panel and the breakers you need, then throw the panel and cabinet on the scrap pile. will cost less than if you just purchased the breakers you needed. Always throw a few extra breakers on an order as well for any commonly needed replacements or expected future additions to have on hand.
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