1. What an Equipotential Bonding Terminal Box Does (Eliminating Potential Difference)
The core function of an equipotential bonding terminal box is toeliminate potential differences within a local area. When equipment leaks current or lightning strikes, there is no potential difference between metal parts, so no current flows through a person touching them simultaneously —no potential difference means no electric shock.
2. Where Is an Equipotential Bonding Terminal Box Mandatory? (5 Categories of Required Locations)
| Location | Type | Requirement |
|---|---|---|
| Bathroom / Shower Room | LEB | Mandatory per GB 50303 |
| Swimming pool | LEB | Mandatory per GB 50303 |
| Hospital operating room | LEB | Mandatory per GB 50303 |
| Equipment Room / Low-Voltage Room | LEB | Recommended |
| Distribution Room | MEB | Mandatory per GB 50054 |
3. How to Set Up LEB in a Bathroom (Example)
① LEB terminal box recessed in the bathroom wall, 0.3–0.5 m above floor level;
② PE conductor run from the floor PE bar to the LEB (BVR-16mm²);
③ Cold water pipe / hot water pipe / heating pipe bonded to LEB with BVR-6mm²;
④ Metal bathtub / metal shower rod / metal fixtures bonded to LEB;
⑤ Floor / wall structural rebar bonded to LEB;
⑥ LEB and MEB are bonded with BVR-16mm².
4. How is equipotential bonding set up in a server room? (lightning protection + grounding)
Equipotential bonding in the server room uses aM-type equipotential bonding network: ① Lay a copper strip grid under the anti-static raised floor (600×600mm); ② Bond all cabinets and equipment enclosures to the copper strip grid with BVR-6mm²; ③ Bond the copper strip grid to the server room LEB terminal box; ④ Bond the LEB terminal box to the building MEB and the grounding electrode, with a ground resistance ≤ 1Ω.
5. Equipotential bonding terminal box selection (LEB specifications)
| Model | Terminals | Enclosure size | Conductor cross-section |
|---|---|---|---|
| LEB-4 | 4-position | 250×180×80 | ≤ 6mm² |
| LEB-6 | 6-position | 300×200×80 | ≤ 6mm² |
| LEB-8 | 8-way | 350×250×80 | ≤ 10mm² |
| MEB-12 | 12-way | 400×300×100 | ≤ 25mm² |
FAQ FAQ
What is the purpose of an equipotential bonding terminal box?
It eliminates potential differences within a local area, bonding metal pipes, equipment enclosures and structural rebar to the same potential to prevent electric shock.
Is an LEB mandatory in a bathroom?
Required by GB 50303A bathroom must have a local equipotential bonding terminal box; without one, it will not pass inspection.
Can LEB and MEB share one box?
No. The MEB is at the building entry point and the LEB is in a local area — different locations and different functions. The LEB must be bonded to the MEB but installed separately.
How is equipotential bonding wired in a server room?
Lay a copper strip grid under the anti-static raised floor, bond the cabinets to the grid, bond the grid to the LEB, and bond the LEB to the MEB and the grounding electrode, with a ground resistance ≤ 1Ω.
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