Vysal Underfloor Heating : Product Catalogue : Electrical Accessories : 25 Amp RCD

Product Catalogue > Electrical Accessories > 25 Amp RCD

25 Amp RCD 30mA Tripping Current

All electric underfloor heating circuits must have 30mA RCD protection to comply with the requirements of BS 7671:2008 (known as the 17th Edition) Requirements for Electrical Installations or, the IEE Wiring Regulations.

Residual Current Devices (RCD) are electro-mechanical devices designed to switch off electric current in the event of an electrical fault. They can detect very small faults before they become dangerous and are an excellent additional protection against electric shock and from fires of an electrical nature. RCd;s work by measuring, indirectly, the leakage current from live conductors to earth. They are not designed to detect overcurrent and are not replacements for fuese or other overcurrent-tripping devices such as MCBs.

30mA RCDs are intended togive some protection from fatal electric shock and protection from fires generated from electrical faults. 100mA RCDs provide lesser protection from electric shock but are primarily intended to give protection from fires generated from electrical faults.

We strongly recommend that electric underfloor heating circuits are individually protected by a 30mA RCD specifically for each circuit. DO NOT combine sensitive loads such as high integrity supplies, freezer supplies, lighting etc into the RCD protection for electric underfloor heating circuits. Modern UK practice is not to use RCD to protect lighting circuits.

The subject of RCDs is complicated and we refer inexperienced installers to go online via the link below where there is an article entitled Understanding RCDs extracted from IET, Wiring Matters, Summer 2006. The article is based on information from The RCD Handbook, The BEAMA Installation Guide to the Selection and Application of Residual Current Devices.

Nuisance tripping (not due to a fault, but either inherent to the normal operation of a device or due to some external cause) can occur with these RCDs. We would expect that most electricians would be familiar with this phenomenon. If tripping occurs, the system must be checked to confirm that there is not a problem.

With regard to heating mats, a false leakage current can be apparent due to the high capacitive effect generated in long cables with AC currents. If your installation is a large one its especially long cable runs would be prone to this. Once the system has been found safe, the solution is to increase the capacity of the RCD until the nuisance tripping is eliminated.

Nuisance tripping can also be caused by other appliances in your house (freezers and water heaters for example) particularly if they are on the same circuit. The external supply itself can also introduce problems.

http://www.voltimum.co.uk/news/6258/consult.experts_hottopics.weeedirective/Understanding-RCDs.html%20-%2050k%20-

We offer the 25/30/2 from Control Gear Direct

Supply voltage 230/240V : 50 Hz

25 Amp Rated Current

2-Pole

30 mA Tripping Current

Cable capacity: 35mm² rigid

Dimensions: 86 x 36 x 74.5 mm (2 modules)

Code	Size
2564	25 Amp CGD