Built to handle demanding commercial loads, this 800-amp unit-mount breaker provides essential long-time and instantaneous overcurrent protection. The HACR-rated device features an interchangeable trip unit, simplifying maintenance and rating adjustments without replacing the entire housing. It fits perfectly into Siemens S4 and S5 panelboards, along with standard motor control centers. When upgrading infrastructure, this model is succeeded by the 3VA55 series via specialized retrofit hardware.
What replacement line and load lugs are compatible with this breaker?
The MD63B800 uses TA3K500 mechanical lugs. Each lug kit accommodates three 1/0 AWG to 500 kcmil aluminum or copper conductors per pole.
What is the adjustable magnetic trip range for this 800A breaker?
The instantaneous magnetic trip settings on the MD63B800 can be adjusted from a low of 4,000A to a high of 8,000A, providing flexibility for system coordination and high inrush loads.
Are there higher interrupting versions of the MD63B800?
Yes. If your system requires a higher short-circuit rating than the standard 50kA at 480V, you can upgrade to the HMD63B800 (rated 65kA at 480V) or the current-limiting CMD63B800 (rated 100kA at 480V).
Can the thermal-magnetic trip unit be replaced without swapping the entire breaker?
Yes, the MD63B800 features an interchangeable trip unit design. You can swap out the internal MD63T800 trip unit while leaving the breaker frame mounted in the enclosure.
SuperClub
Join free. Get 500 SuperPoints.
Earn points on eligible purchases and redeem them at checkout.
We source obsolete and hard-to-find parts every day.
Shipping
Free Shipping Policy
Parcel shipments with item value over $99 qualify for free economy shipping within the continental US. Please call to confirm special handling instructions. We do not charge a handling fee or require a minimum amount on any order. SuperBreakers does not ship on customer accounts.
We strive to ship out your items the same day the order is placed. In rare circumstances SuperBreakers may reserve up to 5 business days to consolidate orders for complete shipment.
Expedited Shipments
Orders being shipped via Next Day Air, 2 Day Shipping or 3 Day Shipping must be received by 3 PM EST to guarantee same-day shipments. Expedited orders only ship on normal business days. Shipments will NOT be sent out on Saturdays and Sundays.
International Shipping
All International orders require a $1,000 minimum order threshold. Due to the special nature of these shipments, we require that these be placed with a SuperBreakers representative. Additional shipping and instructions will apply. All International Orders are Non-Cancel and Non-Refundable.