Which mid-range boards (if any) have Type 1 SPDs available

[timhoward]

Next week I've got a single phase CU change that's a sub-main fed by an over-air cable run supported by catenary wire.
By rights I believe this should have a Type 1 SPD.
My normal go-to board (Fusebox) doesn't seem to list a Type 1 device in their catalogue.

I wondered if anyone can suggest any of the mid-range boards that has a Type 1 device available.
Secondly, can I take as face value what Surge Devices told me - they reckon it was fine to fit one of their devices in another manufacturers CU as it wasn't connected to the bus bar.

 

[pc1966]

Wylex do a beefy type 1+2 SPD but it sure ain't cheap:

100kA 4 Module Single Pole and Neutral Type 1+2 Surge Protector

Disconnect facility for each individual module

www.cef.co.uk

As far as using 3rd party SPD then if they say it is suitable and installed per manufacturer's instructions then I don't see a problem. Very few actually use the busbar or anything similar (Hager have some short formed links for their TPN board option) so it comes down to proper use of short cable links of adequate size. 534.4.10 has conductor size.

Personally for a type 1 SPD setup if the SPD is of the size that has twin terminals for Kelvin (V-wiring) style connections then I would put it in a separate metal DIN enclosure with a main switch and from that feed the CU which can then be whatever your usual choice is. That way you can keep the inductance to an absolute minimum by having:

tails -> main switch -> SPD -> CU

Also if this is overhear is it a TT setup or TN? If it is TT you will need an up-front delay RCD just in case the SPD fails and again you might as well have it as the main switch in a separate box.

 

[pc1966]

I have used these folks before, might be worth a call to get advice and a quote:

Type 1+2 Lightning Current and Surge Arrester (KM1+2-25-1+1 SC) - Kingsmill Industries

System: Single Phase TT/2 Pole Nominal Voltage: 230V AC

kingsmillindustries.com

 

[timhoward]

Thanks for comments. It's an interesting one.
House on a country estate, fed by overhead 3c SWA. Only a 10m run overhead, the rest is underground.

Currently a Contactum Split load board. What is odd is that it was originally TN, and has been converted to TT and back again!
It was TN at point of last EICR (10 years ago).
Since then someone has added an 100ma S-Type main switch and electrode, and this gear is obviously newer than the rest.
And later again someone has decided it doesn't need to be TT and joined up the 3rd core again.

I've yet to do testing and establish what is feasible for ADS and fault protection.

Another contender...

25kA 2 Module Single Pole and Neutral Type 1+2+3 Surge Protector

Suitable for TN-C-S systems

www.cef.co.uk

Though interestingly that says "suitable for TN-C-S earthing". I'll need to dig into why....

 

[pc1966]

Some of the cheaper Type 1 SPD are only type 1, not 1+2 so the level of let-through voltage is higher.

You can feed a type 2 in a normal CU from this but for coordination you normally need a certain inductance, typically given as something like 5-10m of cable. Unless you plan on a sub-main from DNO point to the final CU location then it is impractical to do. So just get a type 1+2 device in the first place!

This download is big (17MB) but has more SPD and related info than you can shake a stick at:

https://www.nvent.com/sites/default/files/acquiadam/assets/E907W-WWEN.pdf

Page 72 onwards talks about the actual SPD.

 

[pc1966]

Thanks for comments. It's an interesting one.
House on a country estate, fed by overhead 3c SWA. Only a 10m run overhead, the rest is underground.

Currently a Contactum Split load board. What is odd is that it was originally TN, and has been converted to TT and back again!
It was TN at point of last EICR (10 years ago).
Since then someone has added an 100ma S-Type main switch and electrode, and this gear is obviously newer than the rest.
And later again someone has decided it doesn't need to be TT and joined up the 3rd core again.

I've yet to do testing and establish what is feasible for ADS and fault protection.

Ah, that is "interesting" to hear. Certainly you would want to check and know what and why.

Sometimes a dealy RCD up-front is used for fire protection in agricultural settings (rodents eating cables) so might be another factor to consider. If good and going all RCBO then no issue with keeping it, even if external box is needed.

Another contender...

25kA 2 Module Single Pole and Neutral Type 1+2+3 Surge Protector

Suitable for TN-C-S systems

www.cef.co.uk

Looks promising. In for lightning protection and no real risk of the cable or its poles being hit then you don't need the bigger sort.

Though interestingly that says "suitable for TN-C-S earthing". I'll need to dig into why....

Some manufacturers have different layouts for TN and for TT.

• Typically for TT you have one SPD element (typically a MOV = metal oxide varistor) from L-N and another (typically GDT = gas discharge tube) from N to E.
• For TN supplies some have all the elements from live to E (as L - E and N - E).

I don't know if there is any specific reasons for this, say relating to energy handling and danger of failing shorted, etc, but many companies use the TT style for TN as well and you can argue that the MOV L-N is better at keeping the surges seen by equipment down, though at the price of higher surge to E on any insulation or class Y filter capacitors that are live-CPC.

Again, if they say it is suitable for the type of supply you have then no worries.

 

[pc1966]

Here is its brother for TT (and indeed all) systems:

50kA 2 Module Single Pole Type 1+2+3 Combined Lightning and Surge Protector

Suitable for all installations [TT, TN-S, TN-C-S, PME]

www.cef.co.uk

 

[pc1966]

Here is its brother for TT (and indeed all) systems:

50kA 2 Module Single Pole Type 1+2+3 Combined Lightning and Surge Protector

Suitable for all installations [TT, TN-S, TN-C-S, PME]

www.cef.co.uk

Down side to those models is they need a 63A backup MCB. Some of the others are good with fuse over 100A so fine of a typical DNO domestic supply.

 

[pc1966]

This model might be your best choice as 200A fuse is enough ultimate backup and suited to all earthing types:

50kA 2 Module 2 Pole and Neutral Type 1+2 Surge Protector

Combined Type 1 and 2 Lightning / Surge Arrestor

www.cef.co.uk

The data sheet gives 4-16mm for cables but regs have 6mm minimum for live on type 1 SPD.

 

[timhoward]

Believe it or not the entire estate is on a 3ph 100A supply. As it's converted into offices and several dwellings there are strict rules about demand, e.g. all cookers are gas !