Products
DEHN · 900450
Single phase · TT, TN-S, TN-C-S (PME) · 1 module · Remote contact: No
Subtotal (1 unit)£74.65/unit
£74.65 ex VAT£89.58 inc VAT
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Mersen · 83020117
Single phase · TT, TN-S, TN-C-S (PME) · 2 modules · Remote contact: Yes
Subtotal (1 unit)£110.56/unit
£110.56 ex VAT£132.67 inc VAT
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DEHN · 900455
Three phase · TT, TN-S, TN-C-S (PME) · 2 modules · Remote contact: No
Subtotal (1 unit)£139.92/unit
£139.92 ex VAT£167.90 inc VAT
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DEHN · 952110
Single phase · TT, TN-S, TN-C-S (PME) · 2 modules · Remote contact: No
Subtotal (1 unit)£139.95/unit
£139.95 ex VAT£167.94 inc VAT
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DEHN · 952115
Single phase · TT, TN-S, TN-C-S (PME) · 2 modules · Remote contact: Yes
Subtotal (1 unit)£179.27/unit
£179.27 ex VAT£215.12 inc VAT
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Mersen · 83020147
Three phase · TT, TN-S, TN-C-S (PME) · 4 modules · Remote contact: Yes
Subtotal (1 unit)£221.74/unit
£221.74 ex VAT£266.09 inc VAT
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DEHN · 952310
Three phase · TT, TN-S, TN-C-S (PME) · 4 modules · Remote contact: No
Subtotal (1 unit)£380.60/unit
£380.60 ex VAT£456.72 inc VAT
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DEHN · 952315
Three phase · TT, TN-S, TN-C-S (PME) · 4 modules · Remote contact: Yes
Subtotal (1 unit)£432.94/unit
£432.94 ex VAT£519.53 inc VAT
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Buying guide
On a TT system the installation earth is a local electrode rather than an earth from the network. SPDs made for TT systems protect between phase and neutral and use a separate spark gap from neutral to earth - often called a 1+1 (single phase) or 3+1 (three phase) arrangement - which is the connection used when the SPD is fitted on the supply side of an RCD.
Questions
- Why does a TT system need its own type of SPD?
- Because the SPD often sits before the RCD, its connection to earth goes through a spark gap from the neutral, so that in normal operation no current leaks to earth.
- Where does it go?
- At the distribution board or consumer unit, as close to the origin of the installation as practical, with short connecting leads.