Class T fuse kit for TITAN lithium batteries - Blue Sea 5502100 block, 225-400A range

Class T Fuse 400A (Blue Sea Systems 5121)

Class T fuse dimensioned drawing — Blue Sea Systems 5112–5121

Class T fuse trip-delay (time-current) curve — Blue Sea Systems

Class T Fuse Kit (400A)

Name: Class T Fuse Kit (400A) - for TITAN 460Ah & High-Current Installs
Brand: TITAN Lithium
SKU: FUSE-TCLASS-KIT
Price: 99.99 GBP
Availability: OutOfStock

for TITAN 460Ah & High-Current Installs

£99.99

Item is out of stock

Descrição do item:

400A peak · 320A continuous · 125V DC · 20kA AIC · Ignition-Protected

Recommended for the TITAN 460Ah and any install with sustained currents above 250A.

What's in the kit

1 × Blue Sea 5502100 Class T Fuse Block (with insulating cover)
1 × Blue Sea 5121 400A Class T Fuse

Class T fuses have an extremely fast short-circuit response and the highest interrupt capacity available in this size class — 20,000A AIC, double the rating of an MRBF. The right choice for high-power inverters, large house banks, and any install where the cabling and BMS allow continuous discharge above 250A.

Why Class T over MRBF for the 460Ah

The TITAN 460Ah has a higher continuous discharge ceiling than our standard packs. A 300A MRBF can be the limiting factor — the Class T's 320A continuous (400A peak) headroom keeps the fuse out of the discharge path until something genuinely goes wrong.

Why two amperage figures?

Blue Sea's product name says “225 to 400A” but the spec table says 320A maximum amperage. Both are correct — they describe different things:

225–400A — the range of fuse sizes that physically fit and are listed-compatible with this block. You can install a 225, 250, 300, 350, or 400A Class T fuse in it.
320A — the holder's own continuous current rating per ABYC E-11 / UL 489. This is the limit on what current can flow through the studs and copper block sustainedly without overheating.

The two numbers reconcile via the marine industry's “80 % continuous” rule: a fuse should not carry more than 80 % of its rating continuously. 400A × 0.80 = 320A, which is exactly the holder's continuous rating. They're saying the same thing two ways.

For a TITAN 460Ah (300A continuous BMS), the 400A Class T is the correct sizing — the BMS will trip first on a sustained overload, and the fuse only blows on a genuine short circuit (where it can interrupt up to 20,000A).

Specifications

Fuse rating	400A peak / 320A continuous (300A inside engine spaces)
Maximum voltage	125V DC (fuse) · 160V DC (block)
AIC (Interrupt capacity)	20,000A @ 125V DC
Ignition-protected	Yes
Cable size	Up to 4/0 AWG
Terminal studs	M8 (5/16"-18) · stainless steel
Mounting	M6 / 1/4" hardware
Base material	UL 94-V0 (high-heat resistant)
Total weight	~0.64 kg
Manufacturer	Blue Sea Systems (PN 5121 + 5502100)

Spare parts available separately: Class T Fuse Block · Class T 400A Fuse

Technical reference

Drawings & curves sourced from Blue Sea Systems product documentation.