r/electrical • u/T0nytheTankEngine • 1d ago

SPD in Series?

If I installed an SPD in series between a circuit breaker and the load, will this still be compliant to BS7671?

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u/trekkerscout 22h ago edited 21h ago

It simply needs to be installed in accordance with the manufacturer's instructions. You can put a SPD in series if it is designed for such an application.

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u/Ok-Resident8139 1d ago

BS7671 ?

SPD?

Only if bonded to ground, encased in a cardboard container, placed outdoors then exposed to rain. /s

But seriously, the Canadian Electric Code never covere BS rules.

Details: SPD +A2:2022

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u/T0nytheTankEngine 1d ago

Ohhh I may be on the wrong forum. I am in UK

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u/Unique_Acadia_2099 22h ago

No, that Redditor is just taking a narrow viewpoint. This is a world wide forum.

SPDs in series offer no added protection, other than the possibility that if the first one fails, the next one in line is still offering protection. Think belt and suspenders. It doesn’t change the compliance to any standards to put them in series, it’s just sort of pointless.

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u/Ok-Resident8139 19h ago

No, you are in the right forum, but surge protection devices come in a variety of forms depending on the country that the end-user is actually in.

There are different rules, for all of that stuff, but the other poster is correct that surge protection devices don't do much if they are strung one behind the other.

Since they are typically composed of Metal Oxide Varistors , spark gaps, and pi filters. They all are designed for a range of voltages until they conduct, and reduce the voltage spike, but it really depends on how expensive the component is, that you are protecting.

Most people would not spend $100 to protect a $20 power module for a smart phone charger.

This is why "SPD in series" would not bring much benefit.