Washington ? Bad wiring and a leak in what’s supposed to be a “blowout preventer.” Sealing problems that may have allowed a methane eruption. Even a dead battery, of all things.

New disclosures Wednesday revealed a complicated cascade of deep-sea equipment failures and procedural problems in the oil rig explosion and massive spill that is still fouling the waters of the Gulf of Mexico and threatening industries and wildlife near the coast and on shore.

The disclosures were described in internal corporate documents, marked confidential but provided to a House committee by BP PLC, the well’s operator, and by the manufacturer of the safety device. Congressional investigators released them.

A senior BP executive, Lamar McKay, cautioned lawmakers, “It’s inappropriate to draw any conclusions before all the facts are known.” But the documents established the firmest evidence to date of the sequence of catastrophic events that led to the explosion and worsening spill, a series of failures reminiscent of the loss of the space shuttle Challenger.

Like the 1986 Challenger disaster, the investigation into the Gulf spill may well show that complex and seemingly failproof technical systems went wrong because of overlooked problems that interacted with each other in unexpected ways.

The April 20 BP rig explosion killed 11 people. Since then, nearly 4 million barrels of oil have spewed from the broken well pipe 5,000 feet under water 40 miles off the Louisiana coast, threatening sensitive ecological marshes and wetlands and the region’s fishing industry.

Congressional investigators revealed Wednesday that a key safety system, known as the blowout preventer, used in BP’s oil-drilling rig in the Gulf had a hydraulic leak and a failed battery that probably prevented it from working as designed.

They said that BP documents and others also indicated conflicting pipe pressure tests should have warned those on the rig that poor pipe integrity may have been allowing explosive methane gas to leak into the well.

In other developments Wednesday:

• The White House asked Congress to raise the limits on BP’s liability to cover damage from the spill beyond the $75 million cap now in law. It also wants oil companies to pay more into a federal oil spill cleanup fund.

• On the Gulf Coast, a new containment box — a cylinder called a “top hat” — was placed on the sea floor near the well leak.